substance, identity and time

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Substance, Identity and Time

Author(s): E. J. Lowe and Harold W. NoonanSource: Proceedings of the Aristotelian Society, Supplementary Volumes, Vol. 62 (1988), pp.61-100Published by: Wiley on behalf of The Aristotelian Society

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SUBSTANCE, IDENTITY AND TIME

E.

J.

Lowe

and

Harold

W.

Noonan

I-E.

J.

Lowe

I

A

tomato

is

sitting

on

the

table.

It

has been

sitting

there

for the

past

five minutes.

But

what makes

the tomato

that is

now

sitting

there the sametomato as the one that was sitting there five

minutes

ago?

A

crazy-sounding

question

One

is inclined

to

reply: 'Nothing

makes t the

same tomato:

it

just

is the

same,

and

there's an

end

on it'. If

pressed

a

little

further,

however,

one

might

continue:

'Look,

five

minutes

ago

a

tomato was

sitting

on

the table.

It

persisted

there, undisturbed,

for

five minutes.

At no

time was the

tomato

removed from the table and

replaced

by

another. And that is

why

the

very

same tomato

is

still there

now,

five minutes later'.Butinvirtue of what did thatoriginaltomato

persist

what

kept

it,

that

very

same

tomato,

in

being?

Again

a

crazy-sounding

question. Surely

one

is

not called

upon

to

explain

why

something

like

a

tomato should

continue to exist

from

one moment to the

next?

One

may

indeed be called

upon

to

explain

the

coming-to-be

r

the

ceasing-to-be

f

a

tomato,

but

surely

not its

continuing-to-be.

sn't the

request

for an

explanation

of the

tomato's

persistence

rather like a

request

for an

explanation of an object's continuing to move with a uniform

velocity

when not

acted

upon

by any

force?

Perhaps

we

might

speak

by

analogy

of

a

'law

of

existential

inertia'.' I think

there

is

something

sound in this

no-nonsense

response-but

I

also

think

that

quite

a

lot of

work needs

to be

done

to earn

a

right

to

use

it.

(And

even

then,

I

do

not

consider that the

response,

in

unquali-

fied

form,

is

appropriate

in

the case of

things

like

tomatoes.)

So far

a number of

subtleties

have been

glossed

over.

For one

thing,

there

is a

distinction to

be

made between

explaining

tomato's

persistence

and

saying

what that

persistence-the

tomato's

'diachronic

identity'-consists

in.

For

another,

it won't

do

just

to

say

that the

persistence

of

something

like a tomato

calls

In

fact,

modern

physics

does mbrace what

seems

to amount

to

just

such

a

law,

in

the

form of

the

law of the conservation of

mass/energy

(though, obviously,

one

could

hardly

appeal

to

this

law

directly

n the

case of

something

as

complex

as a

tomato).







62

I-E.

J.

LOWE

for no

explanation,

without

saying

in some

detail what

exactly

it

takes

to

be

something

like this.

For,

of

course,

if

we

change

the

example

to

one

concerning

a

very

different

sort of

object-say,

a

trumpet-blast--then

the

questions

which

earlier sounded

crazy

transform

nto

quite

sensible ones.

But, then,

what

exactly

is the

relevant difference between

a

tomato

and

a

trumpet-blast?

The

tomato,

one

might

want

to

say,

is

a

continuant--or,

f one

is

old-

fashioned,

a

substance-while the

trumpet-blast

is

aprocess.

Well

and

good,

but this

isjust

fancy labelling.

What is it for

something

to be a 'substance'?A

quick

response

would be: it is to be

something

whose

coming-to-be

or

ceasing-to-be

calls

for

an

explanation

(these

being

'substantial

changes'),

but whose

continuing-to-be

does

not.

But

this

response

would be

too

quick.

For

it is

far

from

clear

yet

that

by

this definition

a

tomato-or

indeed

anything-will

qualify

as a

substance.

Let

us return

to

the

distinction between

explaining

a

thing's

persistence

and

saying

what

its

persistence,

or

diachronic

identity, 'consistsin'. I take it that what is involved here is the

quite

general

distinction

between

providing

a causal

explanation

of

the

occurrence of a

phenomenon

and

saying

in some

revealing

way

what that

phenomenon

really

is-disclosing

its 'real

essence'.

(Compare

the

distinction

between

saying

why

lightning

occurs and

saying

that it is an electrical

discharge.)

However,

even

granting

this

important

distinction,

it

seems clear

that

the

two sorts

of

concern will

be

intimately

related.

In

particular,

it

may well be urged that if no explanation of a thing'spersistence

could be

forthcoming

this

might

be

precisely

because

its

persistence

could not be revealed

to consist in

anything

independently

understandable.

And,

indeed,

I

strongly suspect

that

this is how

matters stand

with

respect

to

some

of

the

things

we are

inclined

to

call

substances--though

not,

I

think,

with

respect

to tomatoes.

However,

in what follows

I

shall leave aside

questions

concerning

the

explanation

of

persistence

in

favour

of

questions concerning the 'essence' of persistence.

To be

in a

position

to

say

in

what a

thing's persistence

consists

is,

in

more familiar

terminology,

just

to be

able

to

supply

a

criterion

or

'principle')

of

diachronic

identity

for that

thing,

and,

more

generally,

for

things

of

its sort.

(In

saying

this

I

presuppose

that

a 'criterion'

in

the

present

context

is not

to be understood

as

an evidential

r

heuristic

rinciple,

but rather as a

metaphysical-







SUBSTANCE,

DENTITYAND TIME

63

cum-semantic

one.)

In

these

terms, then,

what

I

wish

to

maintain is

that there

are

some sorts of

things

(not,

however,

including tomatoes)

for

which no such

criterion

of

identity

can

be

supplied.

In

the

case of

things

of these

sorts,

identity through

time

is

primitive

or

ungroundedas

I

shall

put it).

I

believe,

for

reasons

I

shall

try

to

make

clear,

that there mustbe

ungrounded

identities-ultimately

because

the notion of such identities

underpins

our

very

conception

of

time

itself.

(The

thought

is

not

altogether

novel,

having

strong

Kantian echoes: but

I

hope

that

in its detailed

development

I

may

have

something

new to

offer.)

To this it

may

be

objected-before

I even

begin-that

no

legitimate

advance

may

be

made fromour

onceptions

o

how

hings

must

be. In a

sense,

I

grant

this: but

if

it can be

established

that

we

cannotbut

conceive

things

to be

thus-and-so,

little

enough

of

interest can

be made

of

the

thought

that

things

might

nonetheless

not

be

thus-and-so-for,

ex

hypothesi,

o

positive

content can

possibly

be

conferred

upon

such

a

thought.

II

In

what terms

might

one

hope

to

supply

a criterion of diachronic

identity

for

something

like

a

tomato?

I

think that there

are three

general approaches

one

might

take,

which

I

shall call

theproperty

instantiation

approach,

he

temporal

arts approach

nd

the

substantial

constituents

approach

espectively.

I

shall

argue

that the

first and

second

of

these

approaches

are

inadequate

while

the

third,

which is adequate, demands the existence of ungrounded

identities.

Hence,

if no

other

approach

is

forthcoming,

this

may

be

taken

as

establishing

the

credentials

of

ungrounded

dentities.

Later

I

shall

advance

a

positive argument

in

their favour.

According

to

the

property

instantiation

approach,

the

diachronic

identity

of

a

tomato

is

grounded

in

some

spatio-

temporal-cum-causal

condition

on

the

instantiation

of tomato-

hood-the

crudest version

of

the

theory being

that

the

identity

is

grounded simply in the spatiotemporalcontinuity of such in-

stantiation.2

That

is to

say,

what

supposedly

makes

it

the

case

'

It

may

be wondered

why

I

speak

of

the instantiation

oftomatohood,

s

opposed

to that

of

some cluster

of

non-sortal

properties

(such

as

size,

shape,

colour and so

on).

My

reason

is

that I do not

believe that sortalsare definable

in terms of such

properties:

but

anyone

who thinks otherwise is

at

liberty

to take

my

use of

the term

'tomatohood'

as

merely

abbreviatory.







64

I-E.

J.

LOWE

that the tomato now

sitting

on the

table

is the same tomato

as

the

tomato

sitting

on the

table five minutes

ago

is that there

is

a

spatiotemporally

continuous

sequence

of

place-times

stretching

from the

place-time occupied

by

the tomato

on the

table

five

minutes

ago

to the

place-time

occupied

by

the

tomato

on

the

table

now,

such that

tomatohood

is

fully

instantiated

at

each

place-time

in

this

sequence.

(We

have

to

say 'fully

nstantiated'

so

as

to

exclude,

for

instance,

a

case

in which a tomato

is

largely

but

not

wholly

destroyed

and

subsequently

miraculously

regenerates:

for in such a case one would be reluctant to

identify

the

later tomato with

the earlier

one.)

Obviously,

it is not

important

to

this

account whether or

not

our tomato is removed

from

its table

and

then returned

during

the five

minute

interval-which is

as it

should

be.

Now,

one

objection

which

might

be raised

against

the

foregoing

account is

that it

rules out

a

priori

the

possibility

of

interrupted

or

intermittent

existence

for

something

like a

tomato. I think that this sortof objection is probablyvalid, far-

fetched

though

it

may

seem.

But

it

would

appear

that

it is not

fatal

to the

property

instantiation

approach

in

general.

For

instance,

one

might,

consistently

with this

approach,

loosen the

requirement

on

spatiotemporal continuity

while at the same

time

adding

a

causal

condition

to

distinguish

between

cases of

interrupted

existence of

the

same

tomato and cases of the

annihilation of one

tomato

and

its

later

replacement by

another

createdexnihilo.The condition would be somethingto the effect

that in

order for

later

instantiations of tomatohood to

ground

the

identity

of the

same

omato as

earlier

instantiations,

the later

instantiations

would

have to

be

causallydependent

n the earlier

instantiations

in

certain

appropriate

ways. (Such

a

condition

will

arguably

be

needed

in

any

case,

so

that its

invocation here

should not be

seen as ad

hoc.)

But

there

is

I

think

a

far more serious

objection

of

principle

to

the property instantiation approach. What could possibly be

meant

by

saying

that

tomatohood

is

fully

instantiated at a

certain

place

and time?

Just

this,

surely:

that a tomato

xists

at that

place

and

time. In

fact,

matters are a little

more

complicated

than

this,

but not

in

a

way

that

helps

the

property

instantiation

approach.

It

is

crucial to the

chances

of

successof that

approach

that the 'full'

instantiation of

tomatohood

at a certain

place

and







SUBSTANCE,

IDENTITY

AND

TIME

65

time be

construed

in

such

a

manner

that

multiple

nstantiations

at the

same

place

and time are

excluded.

For

otherwise

the

approach

will

not be able

to

handle,

for

instance,

a case

involving

a bunch

of

contiguous

tomatoes

maintaining

or

changing

their relative

positions

without

losing

contact:

it will

apparently

be

incapable

of

saying

which

f

the

tomatoes at

a

later

time

is to

be identified

with

which

of

the tomatoes

originally

present.

In

short,

'full'

instantiation should

be

interpreted

as

'full and

unique'

nstantiation

at

a

place

and

time.

But this

only

serves to

bring

out more

clearly

than ever that what this talkof

the

('full

and

unique')

instantiation

of tomatohood

at a certain

place

and

time amounts to

is

just

that

there

should

exist

at

that

place

and

time

exactly

one

whole tomato.

However,

such a

proposition

obviously

presupposes,

nd

hence

cannot

help

to

provide,

an account

of the

identity-conditions

of

tomatoes.

For

to

speak

of

one

omato is

just

to

speak

of one

and he ame

omato.

To

this

it

may

be

replied

that

all

that is

presupposed

is

an

account of thesynchronicdentity-conditionsof tomatoes,whereas

what is

now at issue

is

the

question

of their

diachronic

dentity-

conditions.

My response

would

be

to

put pressure

on the

assumption

that

the

synchronic

and

diachronic

identity-

conditions

of

things

like

tomatoes are

independently

intelligible.

Clearly,

it

is not

an

inessential

property

of tomatoes

that

they

are

things

of a sort that

persist

through

time

(even

if

we

can

make

sense of

the

thought

of this

or

that

particular

omato

having only

a

very short-lived existence). And so a synchronic identity-

criterion

for

tomatoes

which

failed to

reflect

this

fact could

not

properly

be

represented

as a

criterion

for the

synchronic

identity

of

tomatoes,

s

opposed

say

to

qualitatively

similar

objects

of

a

more

ephemeral

sort

(such

as,

perhaps,

the

temporal arts

of

tomatoes

with

which we

shall

shortly

be

concerned).

A

synchronic identity-criterion

for tomatoes

should

tell us under

what

conditions

we

have

to

do

with

one and

the same as

opposed

to two distinct tomatoes t a certain time: and this cannot in

general

be

a

matter untouched

by

considerations

of

prior

existence,

given

the

persistent

nature

of

things

that are

of the

tomato kind.

This

might

however

be

challenged

on

the

following grounds.

A

necessary

and

sufficient

condition for

the

diversity

of tomatoes

at a

given

time,

it

may

be

said,

is

the

diversity

of

their locations

t







66

I-E.

J.

LOWE

that

time,

because

no two

tomatoes

can

occupy precisely

the

same

place

(or

indeed

even

partially overlapping places)

at

the

same

time.

And

this,

it

might

seem,

is

a

condition

whose

obtaining

is

not

affected

by

considerations

of

prior

existence.

However,

while of

course

accepting

the

principle

that

tomatoes

exclude one another

from

the same

place

at

the same

time,3

I

do

not

accept

that it

does not

rest

upon

assumptions

concerning

the

diachronic

identity

of

tomatoes,

nor do

I

accept

that

it

can

be

directly

appealed

to as

providing

a

criterion

of

synchronic

identity

for

tomatoes-for,

on the

contrary,

it seemsto me that it

is

a

principle

which

must

if

anything

be

seen to

emerge

rom such

a

criterion

rather

than

to

constitute

it.

I

shall take

these

two

points

in

turn.

First, then,

we

should

appreciate

that

the

capacity

of

an

object

to

exclude another

from the

same

place

is one

that can

only

be exercised

n

the

course

of a finite

period

of

time,

not

just

instantaneously:

so that

the

ascription

of such a

capacity

to an

object presupposeshat it is a persistingsort of thing. Secondly,

however,

we need

to

ask

just

what

it is

about

tomatoes

that

confers

upon

them this

special power

of

mutual

place-

exclusion-a

power

not

possessedby objects

of

many

other

sorts,

such as shadows

and beams

of

light.

We can

after

all

easily

imagine

two

objects

looking

like

tomatoes

approaching

one

another and

merging together: though

the

very

fact of

such

a

merger

would

disqualify

these

objects

from

counting

as tomatoes.

Perhaps the most tempting answer is to say that what is

distinctive

about

tomatoes

is

that

they

are material

objects:

different tomatoes

are

composed

at

any given

time

of different

portions

of

matter,

and different

portions

of

matter

quite

generally,

t

may

be

said,

exclude

one another from

the same

place

at the same

time.

Now,

this answer will

certainly

not

do

as

it

stands,

because

it

fails

adequately

to

accommodate

such

mundane

facts

as that

a

quantity

of

water

may

seep

through

a

portionof porous clay pot. Perhapsindeed one may refinewhat

is

meant

by

'existence

in

the

same

place'

so as to

discount

such

3To

accept

this

is

not,

obviously,

to

deny

that a

place (region

of

space)

may

contain

a

bunch f

tomatoes,

but

only

to

imply

that in

such

a

case

the

place

in

question

must

be

divisible

into

disjoint

sub-regions

each of which

contains

no more

than one tomato.

(It

was,

of

course,

in this

uncontentious sense that

I

spoke

earlier of

the

multiple

instantiation

of

tomatohood at the

same

place

and

time.)







SUBSTANCE,

IDENTITY

AND

TIME

67

cases-stipulating,

for

example,

that

existence

in

the

same

place

implies

co-existence

in

every

spatial

location

within that

place

(though

this

threatens to

run

into the

opposite danger

of

discounting

too

many

ases

by allowing,

for

instance,

two

portions

of

gold

to

coincide

provided

that

their atoms do

not).

But,

what

is

more to the

point,

the answer

already

presupposes

ome

grasp

of

the

notion of

the

identity

and

diversity

of

portions f

matter,

notion from which

the

general

exclusion

principle

must

somehow be seen to

emerge

if it

is

finally

to be endorsed

at

all.

A

grasp

of that

principle

cannot itself be constitutivef our

putative

understanding

of

the

identity

and

diversity

of

portions

ofmatter,

because

it is a

mutual

exclusion

principle

and

hence,

in the

absence

of a

prior

grasp

of what

qualifies

as

a

single

and

distinct

portion

f

matter,

nly

tells us that

something,

we

know not

what,

excludes

another

such

thing

from

the same

place

at

the

same

time-in

short,

it

tells

us

virtually

nothing.

So

if we do

accept

the

answer

now

being

contemplated,

we

must

clearly give

up

the

thought that the power of material objects like tomatoes to

exclude one another from

the same

place

at

the same

time is

what

ultimately nderpins

their

synchronic

identity

or

diversity.

Now in fact

I

should

say

that

I

do

not

think

that we

ought

to

accept

this

answer,

because I

do

not

believe that

a

quite

non-

specific

exclusion

principle

for matter

n

general

s

easily

defensible.

But then it becomes

clearer than ever

that mutual

exclusion

principles

for

specific

kinds of material

objects--including

tomatoes-must have the statusof derivative truthsrelying for

their

appeal

at

least

partially upon

a

prior

grasp

of the

specific

synchronic identity-criteria

appropriate

to

objects

of the

kinds

in

question.4

III

Having,

I

hope,

exhausted

for the

time

being

the

dubious

attractions

of the

property

instantiation

approach,

let

us turn

4The

point

may

be

highlighted by

the

familiar

examples

of cases in

which,

very

plausibly,

we

should

ay

that

two

distinct

material

objects

exist

in

precisely

the same

place

at the same

time-e.g.

a bronze

statue

and

the

lump

of

bronze

of

which

it is made.

What

I

would

emphasise

is

that

such

spatiotemporal

coincidence

is

possible

precisely

because

statues and

lumps

of bronze

have

different

riteria

of

identity-for

this confirms

that the

direction

of

explanation

runs

from

identity-criteria

to

exclusion

(or

non-exclusion)

principles,

rather

than vice

versa.







68

I-E.

J.

LOWE

next to the

temporalartsapproach.Later

on

I

shall

develop

a

further

argument

inimical

to

both of these

approaches.)

This

second

approach

differs

chiefly

from

the

first

only

in

replacing

talk

of the

(full

and

unique)

instantiation

of

tomatohood

at a

certain

place

and time

by

talk

of

the

existence

at

a

place

and

time of a

temporal

part,

or

stage,

or

slice,

of

a tomato.

A

diachronic

identity-criterion

or

tomatoes

will

then

be framed

in

terms

of

spatiotemporal-cum-causal

conditions on

sets or

sequences

of such

temporal parts.

This

approach

has

an

apparent advantage

over the

previous

one in that

temporal

parts

of

tomatoes

plainly

cannot

be

just

the same

sorts of

things

as

tomatoes,

nd hence no immediate

circularity

threatens

when

the

diachronic

identity-criterion

for

tomatoes

is stated

by

reference

to such

entities.5

Whereas talk

of the

(full

and

unique)

instantiation of

tomatohood

at a certain

place

and

time

was

transparently ust

an

oblique

way

of

speaking

of the existence

at

that

place

and

time

ofexactly

newhole

omato,

alk

of the existence

at a certain place and time of a temporal part or stage of a

tomato

is

not

so

obviously

a

mere verbal

ploy.

But

in

another

way

the

temporal

parts

approach

seems

blatantly

ircular. For how are the

'temporal

parts'

of tomatoes

(assuming

indeed that we

countenance

the existence

of

such

things)

to

be

individuated

and identified

save

by

reference

to

the

very

tomatoes of

which

they

are

parts?

The

expression

temporal

part

of a tomato' is a theoretical

term

of

art,

unlike

the

term

'tomato' itself, so that it is not open to one just to leave the

question

of

their

individuation

to 'common

sense'

or

'intuition'.6

Perhaps

however

it will

be useful to

compare

the notion

of

a

temporal

art

of a

tomato

with

that of

a

spatial

part,

which

is a

5

Some

philosophers

do,

I

concede,

believe that a

temporal

part

of

an

object

of

the sort

p

may

(particularly

f

the

part

has

quite

an

extended

duration)

itself

qualify

as an

object

of the sort

(p:

see,

e.g., Anthony Quinton,

The

Nature

of

Things

London:

Routledge

and

Kegan

Paul,

1973),

p.

70. But I

can

see

no

advantage

for them

in

this,

and

only

the

disadvantage

of

having to face the threat of immediatecircularity

which

may

otherwise

be avoided.

6

In

his

second

postscript

to 'Survival

and

Identity' (reprinted

in his

Philosophical

Papers,

Vol.

I

(Oxford:

Oxford

University

Press,

1983)),

David Lewis writes:

'A

person-

stage

is a

physical

object,

just

as a

person

is ... It does

many

of

the same

things

that

a

person

does: it

talks

and walks

and

thinks... It even has

a

temporal

duration.

But

only

a

brief

one,

for

it

does not last

long'

(p.

76).

He

then

goes

on to

argue

that

person-stages

thus conceived

do indeed exist

and

constitute the

temporal

parts

of

persons.

The

first

step

in his

argument

is

this: 'First: t

is

possible

that a

person-stage

might

exist.

Suppose

it

to







SUBSTANCE,

IDENTITY

AND TIME

69

good

deal more familiar.

Now

the

phrase 'spatial part

of

a

tomato'

is

arguably ambiguous

in an

important

way.

It

may

either

be

taken to mean

'part

(=

component,

constituent)

of

a

tomato

which is

spatially

extended'-under

which

interpretation

one

of a

tomato's

seeds,

say,

will

count

amongst

its

'spatial

parts';

or

alternatively

it

may

be taken

to mean

something

like

'object consisting

at

any

given

time of the matter

enclosed

by

a

geometrically

defined

surface not

extending

beyond

the outer

skin of

a tomato'-under which

interpretation

a

quarter-inch-

thick cross-section

through

the middle of a tomato will count

amongst

its

'spatial parts'.

However,

it

seems

plain

that

the

notion

of a

temporal art

of

a

tomato,

if it is

to

play

any

distinctive

theoretical

role,

can

only

be

supposed

to

be

modelled

on

the

second of

these senses of

'spatial

part'-a temporal

part

of a

tomato is

supposedly

a

temporal

'cross-section' or

'slice' of a

tomato. For if

by

a

'temporal

part'

of

a tomato

one

merely

meant,

by

analogy

with

the

first

sense

of

'spatial

part',

a

constituent of a tomato which is temporally extended, then a

tomato's

spatial

and

temporal parts

in these

senses

would

be

precisely

the

same sorts of

things (things

like

its

seeds).

But

unfortunately

it

seems

clear

that

only

spatial

parts

of a tomato

in

this

first

sense constitute

objects

which

are

individuable

and

identifiable

independently

of

the tomatoes

of

which

they

are

parts.

As

against

this

last

claim

it

may

be

urged

that

if

we are

presentedwith a singleslice (= spatialcross-section)ofa tomato

on

a

plate,

we can

individuate and

identify

this

slice

without

being

in

any

position

to

say

from which omato

it has

been cut.

But this

objection

trades on an

ambiguity

in

the notion

of

a 'slice'

(or

spatial

'cross-section').

By

a

'slice' of

a

tomato

one

may

either

mean a

particular

type

of

spatial part

of

a tomato

in the

second

sense

defined

above orelseone

may

mean

something

like

'object

obtained

by

actually cutting

twice

through

a tomato

in two

approximately parallel planes'. The spatial parts of a (whole)

appear

out of

thin

air,

then vanish

again'

(ibid.).

But,

I would

contend,

all

that

Lewis

has

really

succeeded

in

doing

here

is

to

introduce

us to the

fanciful

notion

of a

very

hort-lived

person

i.e.

to

the idea

that a

person

might

in some miraculous

way

be

conjured

into and

out

of

existence

in

a

trice),

and

as such he has

failed

to introduce

us to a

category

of

independently

individuable

entities

in

terms of

which a criterion

of

diachronic

identity

for

persons

might

be

non-circularly

specified.







70 I-E.

J.

LOWE

tomato

in

our second

sense

of'spatial part'

do not

nclude slices of

it

in

this second

sense of

'slice'. There

is no

possibility

of

identifying

lices

of the two

different

sorts-geometrical

lices and

physical

lices,

as we

might

respectively

call them. To

see this we

have

only

to

consider the

different

capacities

which the two

sorts

of slice

possess

to

undergo

certain kinds

of

temporal

change.

For

instance,

a

physical

slice

of a

tomato

can

clearly undergo

all

manner

of

changes

in

shape,

whereas the

very

being

of a

geometrical

slice is

partly

definedby

its

shape.

(In

the case

of

a

physical

slice,

shape only

enters into the definition of how the

object

is

produced.)Again,

if

the contents of a tomato are

rearranged,

the

material

contained

in

one

of

its

geometrical

slices

may

well

alter

considerably

(as

various

seeds,

quantities

of

juice

and

so

on alter

their

locations

within the

tomato).

No

comparable

possibilities

for

changing

its

constituent

material

arise

in

the

case of a

physical

slice,

however. But these

and

related facts also

serve to

show that

geometrical

slices,

unlike

physical ones, are not individuable independently of the whole

objects

of

which

they

are slices: thus a

geometrical

slice

of

a

tomato

is

partly

individuated

by

reference

to

its

relativeposition

within

the

tomato,

which

it

evidently

cannot

alter.

Moreover,

it

is

clearly

geometrical

lices

rather

than

physical

ones which

must

provide

the

spatial

model

for

temporal

arts

or

'slices' of

objects

(since,

apart

from

anything

else,

nothing

very obviously

corresponds

in

the

temporal

case

to the

physical

act of

cutting

which creates a physical spatialslice).

Now,

if

I

am

right

in

saying

that

the

spatial

parts

of

a

tomato

in

our

second sense of

'spatial

part'

are

objects

which

are

not

individuable or

identifiable without reference

to the tomato of

which

they

are

parts,

and also

right

in

supposing

that the

notion

of a

temporal art

of

a

tomato can

only (at

best)

be seen

as

modelled

upon

this

second sense of

'spatial part',

then it

would

seem to

follow that

even

if

we

do

countenance

such

objects

as the

temporalparts of tomatoes, they will not be fit entities in terms

of which

to frame a

non-circular criterion

of

diachronic

identity

for

tomatoes.' In

reply

to this it

might

once

again

be

urged

that

7

By

now

some

readers

may

have wanted

to

accuse

me of

taking

too

narrow a

view

of

the

temporal

parts

approach,

and

in

particular

too

narrow

a

view of

what a

temporal

part

or

stage

would have to

be.

Thus

Sydney

Shoemaker,

a

prominent

adherent

of the

approach,

has written:

'Person-stages

can

be

thought

of as

"temporal

slices",

not of







SUBSTANCE,

IDENTITY AND

TIME

71

in

fact the

notion

of a

temporal part

of

a

tomato

only

presupposes

a

synchronicdentity-criterion

for

tomatoes,

and

hence

can

non-circularly

contribute

to

a

diachronic

criterion.

But

again

I would

reply,

as

I

did

when

a

similar move

was made

on behalf

of

the

property

instantiation

approach,

that

one

is

not

entitled

to

presume

that

synchronic

and

diachronic

identity-

criteria for

objects

like

tomatoes

are

independently

intelligible.

The

temporal

parts

approach

seemed

nitially

to have an

advantage

over

the

property

instantiation

approach

precisely

on this score:but what we have seen is that in

reality

the two

approaches

are

in

the

same boat-and

it

is a

sinking

boat.

IV

I

turn

thirdly,

then,

to

the

final

approach

to

diachronic

identity

that

I

shall

consider-the substantial constituents

approach,

which I

favour.8

According

to

this

approach,

what

underpins

the

persistence

of

something

like

a

tomato

is

the

persistence

of

its

component parts-and by these I mean its 'spatialparts' in our

first

sense

of

the

term

(i.e.

things

such

as

the

seeds and

skin

of

a

tomato). Actually,

this is

of

course

a

slight oversimplication

because a

tomato can

undergo

a certain

amount

of

change

in

its

component

parts

without

loss

of

identity (without,

that

is,

persons,

but of

the

historiesor

careersof

persons.

[Or]

one

might

think

of

a

momentary

stageas a set of propertyinstantiations .. Or one can thinkof a momentarystageas an

ordered

pair consisting

of

a

thing

and

a time'

('Personal Identity:

A Materialist's

Account',

in

Sydney

Shoemaker and Richard

Swinburne,

Personal

dentity

Oxford:

Blackwell,

1984),

p.

75).

However,

the

second

of

these

suggestions

would

reduce the

temporal

parts

approach

to the

property

instantiation

approach,

while

the first and

third would

transparently

make the

individuation of

'stages' parasitic

upon

that of the

continuant

objects

whose

diachronic

identity

they

were invoked

to

account

for. Such

circularity

does

not,

it is

true,

worry

Shoemaker,

who elsewhere

concedes

that

by

his

own

account the

persistence-conditions

fcontinuants cannot

be

non-circularlyspecified

(see

'Identity,

Properties,

and

Causality',

in

Sydney

Shoemaker,

Identity,

Cause,

and

Mind

(Cambridge: Cambridge

University

Press,

1984)).

But I

cannot

agree

that

a circular

specification of persistence-conditions, however non-trivial, may legitimately be

presented

as an account of what

persistence

consistsn.

(Colin

McGinn also

makes

this

point

in his

review of

Identity,

Cause,

and

Mind

in

The

Journal

of

Philosophy

4

(1987),

pp.

227-232.)

So

my

answer to

the

objection

raised

in

this note

is

that

I

adopt

the

interpretation

of

the

temporal

parts

approach

which I

do because

it

seems

to

me

to be the

least

unpromising

on

this

score.

8

I

argue directly

in defence

of

this

approach

and

against

the

temporal parts

approach

in

my

'Lewis

on

Perdurance versus

Endurance',

Analysis

47

(1987),

pp.

152-154

and

my

'The

Problems of Intrinsic

Change:

Rejoinder

to

Lewis',

Analysis

48

(1988).







72 I-E.

J.

LOWE

ceasing

to

be).

This is

especially

obvious

during

the

time that a

tomato

is still

growing.

Nonetheless,

at

any

given

time at

which

it

exists,

a

tomato

must have

component

parts

of certain

sorts-skin, seeds,

quantities

of

juice

and

so

on-and

it is

only

in

virtue

of

the

persistence

from

moment

to moment of

a sufficient

proportion

of such

components

that the

tomato

as

a

whole

manages

to

persist.

A

further

slight

complication

is

that,

as

I

understand

the

term

'component

part

of a

tomato',

certain

objects

which

are

materially

included

in a

tomato

will not

qualify

as

being

amongst

its

component parts,

although

they

will

qualify

as

standing

to the

tomato

in the ancestral

of the

component

parthood

relation-that

is,

they

will be

parts

of

parts

of

parts

. .

of

parts

of

a

tomato.

Thus an electron

in

an

atom in a

molecule in

...

in

a cell in a seed

of a tomato

will

not

qualify

as

a

component

part

of a

tomato

in

my

sense.

My

reason

for

making

this

stipulation

is

that

I

want

to

use

the

phrase

'component

part

of an

object'

in

a

way

that makes

it

legitimate

to regard the sensitivity of an object's identity to changes in

its

component

parts

as

a

largely

conceptual

matter.

(Clearly,

it

can

be

no

largely

conceptual

matter

whether

changes

in

the

electrons

n a

tomato

have

a

bearing

on

its

diachronic

identity,

whereas

it is

very

much such a

matter

that

changes

in

its

grosser

constituents

like its seeds and

its skin

have

such

a

bearing:

and this

is

why

I

want

to

distinguish

the

seeds

and

skin

but

not

the

electrons

as

'component parts'

of the

tomato.)

It

is

clear

that

the

substantial constituents

approach

cannot

and

does

not

even

purport

to offer

an

exhaustive account

of the

persistence

of

substances:

t

only

offers

a

schema

or an

account of

the

persistence

of

any composite

substance

in

terms

of

the

persistence

of its

component

parts.

I

say

a

'schema'

because

the

approach

does

not

presume

to

be able

to

tell

us,

in advance of

empirical

scientific

inquiry

and

theory-construction,

ust

what

the 'component parts' at any point in the hierarchy of

composition

will

be. In

this

respect

the

approach

is

utterly

different

from the

previous

two

approaches,

both

of

which

are

thoroughly

aprioristic

in

character.

A

clear

consequence

of the


approach

is, however,

its commitment

to the existence

of

ungrounded

dentities t

the

base of the

hierarchy

of

composition,

and on

this

issue

the

approach

does take

an

a







SUBSTANCE,

IDENTITY

AND TIME

73

priori

stance.

Some

thing

or

things-be

it

primitive

hyle

or

quarks-must simply persist,

without

rhyme

or

reason,

and

in

this all

higher-level

material

persistence

must

ultimately

be

grounded.

However,

here it

may

be

felt that

our

third

approach's

combination of

empirical

and a

priori

claims renders

it

particularly

vulnerable.

For

who is to

say

that

physical

science

will not in

due

course reveal a

way

to account

for the

persistence

of

so-called 'fundamental'

particles

in terms of

spatiotemporal-

cum-causal relations between

non-persistent

entities of some

sort

(not

indeed

concocted

pseudo-entities

like

'time-slices',

but

something

the

postulation

of whose

existence

would

be

empiri-

cally well-motivated)? Certainly,

in the

present

tate of

physical

science the


approach

looks

to

be

vindicated:

for

the

fundamental

(non-composite) particles

of

modern

physics

are

distinguishable

into those

that

are

and those

that are not

'stable',

and the 'half-life'

of

such a

particle

(infinite

in the case of a stable particle like the electron) is apparently

taken to

be

an

essential

property

of

that

particle

which

is not

further

explicable

(like

also

the

charge

on an

electron).

But

perhaps

this

is

just

a

parochial

feature

of

contemporary physical

theory?

In

fact, however,

I

do not

think that the

commitment

to

ungrounded

dentities

s

as vulnerable

to the future

developments

of

physics

as

it

might

appear

to

be.

What

undoubtedly

is an

empirical issue open to futurerevision is the correctnessof our

contemporary

theory

of

matter.'

What

is

not

I

think

thus

vulnerable

is

some broad notionof

matter as the ultimate

and

itself

ungrounded

ground

of all

physical persistence.

My

reason

for

thinking

this

is,

as

I

indicated

at the

outset,

that

I

believe

that

the

very

concept

of time

annot be

divorced from

such a notion

of

matter. For

time,

I

consider,

essentially

involves

change,

nd

a

change

can

only

be understood

by

reference o

something

which

persists through that change. But to deny that there is anything

9

It

is worth

emphasising

that the

substantial

constituents

approach

does

not demand

that the

ultimate

constitution of

material

things

be

particulate

n

nature,

as

contemporary

physical theory

would

suggest

it is

(making

due

allowance,

of

course,

for the

wave/particle

duality

of

quantum

phenomena).

Thus

the

approach

can

readily

allow,

for

instance,

that

at its most

fundamental

level

physical reality

might

have to

be

described

by

means

of a

vocabulary

of mass

nouns

rather

than

by

one

of countnouns.







74

I-E.

J.

LOWE

whose

persistence

is

ungrounded

is to

imply

that

everything's

persistence

may

ultimately

be

accounted

for in

terms

of

change,

which

conflicts

with

the

stated

dependency

of the

notion

of

change

on

the notion of

something persisting

through

change.

Thus

expressed,

the

argument

is no

doubt

suspiciously

abstract

and

condensed-but

I

shall

try

in what

remains

of

this

paper

to

spell

it

out in

more

convincing

detail.

V

The first

premise

is

that time

essentially

involves

change-by

which

I

mean that time

essentially

involves

happenings

r

events.'•

I

do

not

necessarily

want

to

imply

by

this

that

there could

not

be

time

in a

universe

which was

not

qualitatively

distinguishable

from

one

moment to

the

next

(though

nor

do I

particularly

wish

to defend the

suggestion

that

there

could).

All I

am

saying

is that

it is

partly

constitutive

of

the

notion of time

that time

should

embrace events or happenings, and that events or happenings

are to be

understood as

changes--although

not

necessarily

changes

to

something

or in

something

(this

would

be too

easy

a

way

to

argue

for

the

necessity

of

persisting

substance).

When

a

change

occurs,

something

begins

to be

the case

which

was

previously

not the

case-for

instance,

it

begins

to be the

case

that a

light

is

glowing

or that

there

is

noise in a

certain

room."

Change

in

this

sense

could

conceivably

still

occur

in

a

qualitatively

"o

n

'Time without

Change'

(reprinted

in his

Identity,

Cause,

nd

Mind,

op.

cit.),

Sydney

Shoemaker

argues

that at least

in

some

logically

possible

worlds it

could be

reasonableto

hypothesise

that

a

period

of time

had

elapsed

during

which

nothing

whatever

had

changed

in

any way.

I

am

not

persuaded

by

his

argument,

though

I

cannot

discuss

it

here.

But,

in

any

case,

it is clear that

the

argument

cannot be

construed

as

establishing

that

time

might

pass

in the absence

of

any

change

whateverwithout

presupposing

that

the

persistence

of

objects

in such

a

world

would

not

be

grounded

in

spatiotemporal-cum-

causal conditions

on

sequences

of

momentary

entities

(such

as

durationless

time-slices'),

since the continual comings-to-be and ceasings-to-be of such entities would precisely

constitute

changes

during

the

supposedly

changeless

period

of

time

(even

though

no

qualitative

hange

need

be

involved

in such

a

case).

So Shoemaker's

argument,

even

if it is

correct,

cannot be used

to

any

effect

against

me

by

adherents

of

the

views

of

persistence

which

I am

attacking,

at least as far

as

my

first

premise

is

concerned.

"

It is

customary

when

discussing

change

to

distinguish

between

'real

changes'

and

'mere

Cambridge

changes'-e.g.

between

Socrates's

dying

and

Xanthippe's

becoming

a

widow.

But

since the latter sort of

change

is

arguably parasitic upon

the

former,

it is not

crucial to

my

argument

to restrict the sense

of'change'

it

invokes

to

that

of'real'

change.







SUBSTANCE,

IDENTITY

AND

TIME

75

unvarying

universe-for it

might begin

to

be the

case, say,

that

something

was

yellow

where

previously

omething

lse

qualitatively

indistinguishable

was

yellow.'2

(Whether

this

is

really

possible

depends

on the status of

the

principle

of

the

identity

of

indiscernibles.)

The

second

premise

of our

argument

is

that a

change

can

only

be

understood

by

referenceto

something

which

persists

hrough

that

change.

Again,

it

is

not

being urged

that a

change

must

be

understood

as

a

change

in

or

to

something

which remains

the

same

throughout

that

change.

For some eventsare not

changes

in or

to

things

in

any

very

obvious sense

at

all.

All

that

is

being

urged

is that when

something begins

to be the

case

which was

previously

not the

case

(i.e.

when a

change

occurs),

there

must

exist at the time of

the

change something

which

also existed

prior

to the

change.

For

suppose

on the

contrary

that

nothing

existing

at the

time of

the

change

existed

prior

to the

change:

that

would of course

imply

that

everything

n existence

at

the

time

of the supposed change had begun to exist at that very time.

However,

what

is

it

to

say

this but

just

to

say

that the

time

in

question

was the

beginning

of

the

universe,

and hence

the

beginning

of

time?

But the

beginning

of time

cannot

be the

time

of

any change

n

our

sense,

since

we cannot

meaningfully

speak

of

anything's

beginning

to

be

the

case

then which

was

previously

ot

the

case.'3

Hence

we

have reduced

our

original

supposition

to

absurdity.

No doubt thisreasoning may appear sophisticalon firstsight,

but

I

believe that

deeper

examination

will

vindicate

it.

Suppose

I

tell

you

that

nothing

hat has existed

between

now

and

five

minutes

ago

existed

earlier

than

five

minutes

ago:

what can

you

make

of this

but

that I

am

saying

that the entire

universe

began

to

exist five

minutes

ago?

The

earth,

the

sun,

the stars-all these

and

everything

else

existing

now

or

in the

past

five minutes

began

to

exist,

I

say,

no earlier

than five

minutes

ago:

how

could

12

Thus

consider

a

universe

containing just

two

balls,

one

yellow

and

the

other red

but

otherwise

qualitatively

indistinguishable

from one another:

and

then

suppose

that

at a

certain moment

the

yellow

ball turns red

while the

red

ball turns

yellow

(and

nothing

else

changes).

The states

of

such a universe before

and after

the

change

would differ

only

in

respect

of

the identities

of

the ball

which was

red

and

the

ball

which

was

yellow.

13

This

means

that if we

want

to call the

beginning

of the

universe

an

event,

we

had

better

make

this an

exception

to the

rule

that events

are

changes.







76 I-E.

J.

LOWE

you

credit

this and

yet

still

make sense

of

the

thought

that there

were events

happening longer

than five minutes

ago?

Ex

hypothesi,

o record

f

any

such

events could

possibly

now

exist. So

what

would

be

the difference

between

talking

of

these

supposed

events as

having

ccurred

arlier than five minutes

ago

and

talking

of

them

as

belonging

to an

altogether

different

space-time

continuum--another

'possible

world'?

But

perhaps you

will

dispute

the

suggestion

that

no record

of

these

supposedly

earlier events

could

now

exist-urging

that

this trades on an

ambiguity

in the term 'record'.A record

may

either be an

object

earing

a

trace of some earlier

event,

or else

it

may just

be an

effect

of

some

earlier event.

But,

it

would

seem,

only

records

in

thefirst

sense

could

not exist in our

hypothesised

case:

there

might

still

be states f

presently

existing objects

which

could

be

attributed

to

causeswhich

happened

more than

five

minutes

ago.

However,

it

seems to

me that

to

argue

in

this

fashion is

to

beg

the

very

question

at issue. Our

question

is

what

reasonwe could have, in the hypothesisedcase, to supposethat

any

events occurred earlier

than five

minutes

ago:

it is no

answer

to

say

that

we could

attribute various states

of

presently

existing

objects

to

causes

which

occurred more

than five

minutes

ago

without

explaining

with

what

justification

we could

suppose

causal

relationships

to

be

capable

of

embracing

a

timespan

exceeding

five minutes

in

the

past.

After

all,

the

putative

causes

of these

present

states would themselves

recisely

be events n the

disputedategory. urthermore,I find it very hard to see how any

such

justification

could be

forthcoming:

for

how

could

the

required

causal

influences

have been

propagated

in

the absence

of

any objects

surviving

from

the

alleged

earlier

time

into the

current

five-minute

period?

No

photons,

for

instance,

ransmitted

from

objects existing

in

the

alleged

earlier

period

could

be

received

by

us-for all

existing photons, being persisting

objects

themselves,

would

ex

hypothesi

ave existed for

no

longer

than

five minutes.

It

remains now

to

be shown

exactly

how

these

considerations

lead

to

our

declared conclusion.

As I

remarked

earlier,

to

deny

that there is

anything

whose

persistence

s

ungrounded

is

to

imply

that

everything'sersistence may

ultimately

be

accounted

for

in

terms of

change.

This

may clearly

be seen

by

reference

o the

two

approaches

to

persistence

discussed

previously-the

property







SUBSTANCE,

IDENTITY

AND

TIME

77

instantiation

approach

and

the

temporal partsapproach-both

of

which

may

be taken

to

deny

the need

to

appeal

to

ungrounded

identities

in

giving

an

account

of

persistence.

According

to each

of

these

approaches,

the

persistence

of an

object

is

to be

accounted

for

by-that

is,

is

to

be

regarded

as

consisting

n-the

obtaining

of

certain

spatiotemporal-cum-

causal

relations between

non-persisting

entities of

some

sort:

instantiations of

appropriate properties

at

certain

place-times

according

to the

first

approach,

and

'time-slices'

of

objects

according

to the second

(time-slices

which needto be instantaneous

if the

theory

is to be

worth its

salt-for

if the slices

have o

persist

primitively

even

only

for a

short

duration,

the

theory

cannot

pretend

to offer an account of

persistence

as

always grounded).

However,

this means

that

both

approaches

account

for

all

persistence

n

terms

of

change.

On the

temporal parts

approach

this is

evident,

since

each

of

the time-slices of

a

persisting

object

has

to come nto

being,

and each

such

coming-to-be

constitutes

a

changenecessary for the continued persistenceof the object in

question.

But it

is

quite

as evident also

on the

property

instantiation

approach.

Clearly,

this latter

approach

must

be

committed

to

denying

that the instantiation

of,

say,

tomatohood

at

a

certain

place-time

is

something

essentially

having

a

duration

extending

beyond

that time.

The

theory

must

presume

that

tomatohood

isfreshly

nstantiated

at each

place-time

in

the

history

of

a

single

tomato,

since

if

it were

compelled

instead to

say that no such fresh instantiation is required from time to

time,

then it would become

transparent

that

its

proposal

would differ

only verbally

from the

claim

that

tomatoes

ust

persist.

In

short,

instantiations

must

be treated

as

events

or

changes.

So

according

to

both

of these

approaches,

everything's

persistence

is

ultimately

to be accounted

for

by

references

to

changes

of

some

sort-either

the

momentary

instantiations

of

certain properties or the comings-to-be of durationless time-

slices.

But

the

very

notion of a

change,

we

have

argued,

presupposes

hat

of

the

persistence

of

at

least

something

hrough

that

change

and

so cannot be

appealed

to

in

giving

a

perfectly

general

account

of what the

persistence

of

objects

consists

in.

The

persistence

of

at

least some

sorts

of

things

must,

then,

be

primitive

or

ungrounded,

in

that

it

can consist

neither

n







78

I-E.

J.

LOWE

relationships

between

non-persisting hings

nor

n

the

persistence

of

other

sortsof

things.

This

must,

I

have

argued,

be

presumed

in

order

to make sense of

time at

all,

given

the

necessary

connection

between the

concepts

of

time and

change."

4

This

paper

was

largely

completed

before

the

publication

of

an

exchange

on the

subject

of

persistence

between

Mark

Johnston

and Graeme

Forbes in The Aristotelian

Society's

Supplementary

olume XI

(1987).

It will be clear to

any

reader

of that

exchange

that

my

sympathies

lie

rather more

withJohnston'sposition

than

with

Forbes's,

but

that

there are

also

considerable

differencesbetween

my

position

and

Johnston's.

(It

will be

equally

evident that

my

position

has

some

strong

affinities

with

the one

that Saul

Kripke

has defended in his celebrated

lectures on

identity

over

time.)

I

am

grateful

to Susan

Lowe

and to David

Over

for

helpful

discussions

of

an

earlier

draft.







SUBSTANCE, IDENTITY AND TIME

E.

J.

Lowe

and Harold

W. Noonan

IIH-Harold

W.

Noonan

I

Jonathan

Lowe

argues

that there

must be

some

things

whose

identity

over time

is

primitive

or

ungrounded,

ultimately

because the notion of such

ungrounded

identities

underpins

the

idea

of

time

itself. For

such

things,

he

claims,

no

criterion

of

diachronic

identity

can

be

supplied.

But

what is

'a

criterion

of

diachronic

identity'?

Lowe

emphasises

that what he

is

concerned

with

is

not

an evidential

or

heuristic

principle,

but

a

metaphysical-cum-semantic

one.

The

provision

of a criterion of

diachronic

identity

for

things

of a

kind

would not

merely

be

a statement

of what would count

as

evidence for the identity over time of a thing of that kind, but a

statement

of what the

identity

over

time,

and hence

the

persistence

of

such a

thing,

would

consist

n.

Lowe

distinguishes

hree

approaches

to

the

provision

of

such a

criterion and

argues

that two

are

unsatisfactory,

whilst

the

third,

which he

favours,

implies

the existence

of

persisting

entities

for

which no

criterion

of diachronic

identity

can

be

given.

These three

approaches

he

labels

'the

property

in-

stantiation approach', 'the temporal parts approach' and 'the

substantial

constituents

approach',

the last

being

the one

he

favours.

However,

I

wish

to

begin by

motivating

and then

explaining

an

alternative

point

of

view

from

which

these

issues can

be

approached.

I

shall then

introduce

two senses

in

which it

might

be

held

that

the

identity

over

time of

some

persisting

things

is

ungrounded,

but

argue

that neither

Lowe,

nor

anyone

else,

and

in particularnot Kripke (withwhose views Lowe indicatesthat

he thinks his

own have

affinities)

hasproven

hat

there must

be,

or

are,

things

whose

identity

over

time

is

ungrounded

in

either

of

these

senses.

But

my

main concern

will

not

be

to

argue

against

the

possibility

of

ungrounded

diachronic

identities

(for

which

there

may

well

be

good arguments)

but to

get

clearer

about

what







80

II-HAROLD

W.

NOONAN

precisely

we are

seeking

when we

enquire

after

the

criterion

of

diachronic

identity,

or

the

persistence

conditions,

of

things

of

a

certain

kind.

II

At first

sight

there

seems

to be no

difficulty.

For

any

kind of

persisting thing

K,

in

addition to the identification

problem

for

Ks,

i.e. the

problem

of

specifying logically

necessary

and

sufficient

conditions

for

being

a

K,

there

is

also the

problem

of

specifying

the

logically

necessary

and

sufficient

conditions for

the

identity

of a

K

existing

at one

time

and

a

K

existing

at

another.

Thus

the

problem

of

personal

identity

over

time

is

the

problem

of

saying

'what

are

the

logically

necessary

and

sufficient

conditions for

a

person

P2

at a

time

t2

to be

the

same

person

as a

person

P,

at an earlier time

tl'

(Swinburne

1976:223).

The

(less

interesting) problem

of

ship

identity

over

time

is

precisely

analogous:

what

are

the

logically

necessary

and

sufficientconditions for a

ship

S2

at a time

tz

to be the same

ship

as a

ship

S,

at

an earlier

time

tj?

And mutatismutandis

or the

rest

of

the

problems

of

identity

over

time

discussed

by philosophers.

In

addition to these

problems

of diachronic

identity,

there are

also

problems

of

synchronic

identity,

which can be

stated

similarly.

Thus there

is

the

problem

of

synchronic identity

for

persons:

what are

the

necessary

and

sufficient

conditions

for

two

persons

[i.e.

persons

identified

by

distinct

descriptions]

at a

given time to be the same person?'(Swinburne 1976:228);there

is the

less

interesting problem

of

synchronic identity

for

ships,

and so

on.

That

these

problems

exist,

that

they

make

sense,

and

that

we

can

fruitfully

discuss

them,

seems evident. For

what

else

are

we

doing

when

we

debate

such

puzzle

cases as Locke's

Prince

and

Cobbler,

Shoemaker's

Brown

and

Brownson,

the

Ship

of

Theseus,

or the

(non-fictional)

cases

of

'split-brain'

patients?

Either these debates are a lot of nonsense, it seems, or these

problems

about

identity

are

genuine

ones. And

so

most

philosophers

are content

to hold that

they

are indeed

genuine

ones

(cf.

Kripke's unpublished

lectures

on

identity

over

time for

similar

remarks).

But

when

one looks

closely

at

the

formulations

of these

apparently genuine

problems

it is

easy

to

become

puzzled.

They







SUBSTANCE,

IDENTITY

AND

TIME

81

seem

to be

requests

for

the

specification

of

the satisfaction

conditions of

certain

relations--personal

identity

over

time,

or

ship identity

over

time,

for

example.

But

how

can this

be?

There

are

not different kinds of

identity

to

be

differently analyzed.

There is

just

the

one

relation of

identity,

and there

is

nothing

in

any

way

puzzling

about it.

As

David

Lewis

puts

the

point:

'Identity

is

an

utterly

unproblematic

notion.

Everything

is

identical

to itself.

Nothing

is identical to

anything

else. There

is

never

any problem

about

what makes

something

identical

to

itself;

nothing

can fail to be. And there is never

any

problem

about

what

makes

two

things

identical;

two

things

never can

be

identical'

(1986:192-3).

How then

can

it

make

sense

to

ask,

for

example,

what makes a

person

existing

at

one

time identical

with

a

person

existing

at

another? If the

person existing

at the

earlier time

is

identical

with the

person

existing

at

the

later

time,

the

question

is a

request

for

an

account of what makes

a

thing

identical

with

itself. Whilst if the earlier person is distinct fromthe later one,

the

question

is

a

request

for

an account

of what

makes

two

things

identical.

In

either case it is

unanswerable.

The same

problem

confronts a

request

for an

account of

what makes

two

persons

(personsspecified

by

distinct

descriptions)

at

one

time

identical.

Either

they

are,

or

they

aren't.

If

they

aren't

nothing

makes

them

identical.

If

they

are,

then

their

identity

is

the

identity

of

a

thing

with

itself,

and

so

again

makes 'them' identical.

Of

course,

statements of identity can be informative,and so the possibility

is

still

left

open

of evidential or heuristic

principles

stating

what

evidence

would

count

in

favour of

claims

of

personal

identity

or

ship identity,

or

whatever. But the

'semantic-cum-metaphysical'

problem

of

what

constitutes

dentity

(whether

diachronic

or

synchronic)

for

things

of a

kind now

begins

to

look

like

a

nonsense.

III

The

basic

thought underlying

this

argument

is twofold:

first,

identity

is

not,

as

Locke

said,

'suited

to

the

idea',

there

isjust

the

one

relation

of

identity,

the

relation

everything

has to itself

and

nothing

else,

and

secondly,

this notion

is

unanalyzable

in

any

'For this line

of

thought

see,

apart

from

Lewis,

B.

Brody

1980.







82

II-HAROLD

W. NOONAN

more fundamental terms.

How

then can there be both

problem

about

personal

identity

and a

distinct

problem

about

ship

identity?

How

can

there

be both

a

problem

about

diachronic

personal

identity

and a

distinct

problem

about

synchronic

personal

identity?

And,

more

fundamentally,

how

can

any

of

these

problems

make

sense?

One

response

to this

difficulty

would

be to

side

with

Locke

and

to

deny

the

uniqueness

of the

identity

relation. But there

is a

better

way,

which is

to

deny

that

the

genuine

problems

which

philosophers

are concerned with when

they

debate

topics

under

the

title of

'problems

of

(synchronic

and

diachronic) identity'

are

problems

about

identity

at

all.

Rather,

what

they

are

problems

about

is

kind-membership.

This

suggestion

is,

of

course,

a

wholly

unoriginal

one,

the

clearest

expression

of which is

in

Quine (e.g. 1976).

According

to

Quine 'any

collection of

particle stages,

however

spatio-temporally gerrymandered

or

dispersed'

counts

as a physical object. The world's water is a physical object.

There

is

a

physical object

part

of which is a

momentary stage

of a

silver dollar

sometime in

1976

and the

rest

of which is a

temporal

segment

of the Eiffel

Tower

through

its

third decade.

Any

two

momentary objects,

taken at

different

moments,

are

time slices

of one

physical object-time

slices

indeed of

many

such.

However,

most

such

physical

objects

are irrelevant

to

our

concerns,

and

go

unnamed

in

our

language.

But some do

not;

though ontologically on a par with the rest, these occupy a

favoured

place

in

our

language

and

conceptual

scheme.

For

any

such favoured kind

K

of

physical object

there

is

the

problem

of

specifying

the conditions

a

physical

object

has

to

satisfy

to be a

K.

Thus

there

is

the

problem

of

specifying

the

conditions

a

physical

object

has

to

satisfy

to be

a

ship,

or a

person,

a

river,

or a

body

of

water.

Now

according

to

Quine

the

temporal parts

of

a

physical

object need be related in no way that is of interest to us. But

when we

consider,

say,

what conditions

a

physical

object

has

to

satisfy

to be a

river,

the

situation is

different.

It is not

enough

for

a

physical object

to be

a river

that its

momentary

stages

have a

certain

character;

in

addition

they

must

be inter-related

in

a

certain

way-they

must

be river-kindred.n

Quine's

view it is the

specification

of

this

relation

which

philosophers

are

concerned







SUBSTANCE,

DENTITY

AND TIME

83

with when

they

debate

the 'criterion

of diachronic

identity'

for

rivers.

But

in

specifying

the

conditions

of river

kinship

we

are

not

stating

conditions for

identity,

but

merely

conditions

for

being

a

river.

It

is,

in

Quine's

view,

the

same

with

the

problem

of

synchronic

identity

for

rivers. Insofar

as

it

makes sense

it

is

not

a

problem

about

identity

at

all.

Though

it is

not

sufficient

for

a

physical

object

to

be

a river that its

momentary

stages

have

a

certain

character,

still,

it

is

necessary.

A

momentary stage

of

a

river

differsin intrinsiccharacter

from,

say,

a

momentary

stage

of a

cow.

Thus

there is the

problem

of

saying

what

this character

is.

But

nothing

can

count

as a river-at-a-moment

unless

its

parts

at

that

moment

stand to one

another

in certain relations.

It

is

these

relations that are

discussed under

the

misleading

title

'the

criterion of

synchronic

identity

for

rivers'.

This

Quinean

conception

of

problems

of

synchronic

and

diachronic

identity

as

reducible

to

problems

about

kind

membership seems to me very plausible, indeed wholly

compelling.

But

it is

bound

up

in

Quine,

as

in the

exposition

above,

with

an

idea that

many

philosophers

ind

a

good

deal

less

compelling-the

idea

that

everyday

things

like

ships

and

people

are

'four-dimensional

worms',

with

temporal

as well

as

spatial

parts.

But

I want to

suggest

that we can take on

board

the

more

attractive

of

these

Quinean

ideas

without

committing

ourselves

to the less attractive one. However, in order to make good the

claim that the so-called

problem

of

identity

over

time

for a

particular

kind

of

thing

K is not a

problem

about

identity

at

all,

but

solely

a

problem

about

kind-membership,

we need

a

formulation

of the

problem

in which the

notion

of

identity

does

not occur.

In the

absence of

such a formulation

the claim

is a

fraud.

So what

might

such a formulation be

if we do not

presuppose

the four-dimensionalontology?

We can

approach

an

answer to

this

question

if we

begin by

asking

what information a solution

to the

problem

of

K-identity

over

time

would

provide.

The answer

is that

it would

provide

an

account

of the distinction

between

those

changes

a

K can

survive,

and

those it

cannot,

that

is,

an

account

of the

sort

of

history

that

is

a

possible

one for a

K,

an account

of the variations







84

II-HAROLD W.

NOONAN

and

constancies uch a

history

must

display,

and

those it

may

display

(notice

that the

only necessity

n

question

here is

de

dicto).

In

asking

what

K-identity

over

time

consists

n,

then,

what

one

is

asking

for,

in

part,

is

a

specification

of

certain

necessary

conditions

of

being

a

K,

namely

those identifiable

by

specification

of

the

relation R

satisfying

the

following

schema:

(1)

Necessarily

for

any

(thing

of

kind)

K,

x,

for

any

times

t

and t', if x exists at t and x exists at t' then Rxtt'.

The

hope

is

that

such conditions can be

informatively

specified,

i.e.

can

be

specified

without

use

of the

very

concept

K

which

is

being

analysed (whether

the

concept

of

identity

eeds to

be

employed

is

neither

here

nor

there).

But,

of

course,

in

asking

what constitutes

K-identity

over

time

one is

asking

for

more than

the

specification

of

certain

necessary

conditions

of

K-hood.

The four-dimensionaltheorist can explain this 'more' very

simply:

what

one

is

asking

for,

he

can

say,

is

a

specification

of

a

relation R

such

that it

is

a

sufficient

condition of

a

physical object

being

a K that

all its

temporal

parts

are

pairwise

related

by

R

(sometimes,

as

in

Perry

1972,

such

a

relation

is

called

the

'unity

relation' for

Ks).

But

if

we do not

presuppose

the four-

dimensional

ontology,

we

must

express

the

request

differently,

namely,

as the

request

for a

specification

of

a

relation

R

such that

for any x, it sufficesforx's being a K that R relatesall ordered

triples

<x,t,t'>

where

t

and

t'

lie

within the

period

of x's

existence.

That

is,

the

request

is for a

specification

of

a relation

R

satisfying

the

condition:

(2)

Necessarily,

for

any

x,

if

for

every

t

and t'

ifx

exists

at

t

and x

exists at t'

then

Rxtt',

then x is a

K.

However,

the

specification

of

such a relation

may

be

wholly

uninformative(naturallythe sameis true of thespecificationofa

four-dimensional

unity relation).

To ensure that this is not so

(to

ensure,

in

other

words,

that the

specification

contributes

to the

analysis

of

the

concept

of a

K)

we need to

appeal

once

more

to

schema

(1)

and

require

(at

least)

that the relation

satisfying

(2)

be

specified

as

the

relation

whose

satisfaction

by any

ordered

triple

<x,t,t'>

is

entailed

by

(and

entails)

thejoint

satisfaction

by







SUBSTANCE,

IDENTITY

AND

TIME

85

that

triple

of

some set of relations

R',

each

of which

satisfies

schema

(1),

but is

specified

without

the use

of the

concept

ofa

K.

(In

other

words,

the

specification

of

the relation

satisfying

(2)

must be of

the

form: 'the relation

R

such

that

necessarily,

an

ordered

triple

<x,t,t'>

satisfies

R

iff

it

satisfies

all of

R,

...

R,'-where

R1

... Rn

are

relations

satisfying

schema

(2)

and

specified

in

the

description

given

without

the use of the

concept

of a

K.)

This, then,

I

suggest,

is

what the

request

for 'a criterion

of

diachronic

identity

for

Ks',

or

an account of

what constitutes K-

identity

over

time,

comes down

to when

properly

expressed.

It

would

perhaps

be

better

described

as

a

request

for

'the

diachronic

criterion

of K-hood'.

What

of

the

request

for

a

criterion

of

synchronic

identity

for

Ks,

and

its

customarily

assumed

distinctness

from the

request

for

a

criterion

of

diachronic

identity?

Familiar

examples

(e.g.

in

Perry

1972)

make

it

evident

that

it

is

at least

logically possible

to

be in a state in which one's

grasp

of the

concept

of a K is

partial

in

such

a

way

as

to make it

tempting

to

say

that

whilst one

grasps

the criterion

of

synchronic

identity

for Ks

one does not

grasp

their

criterion

of diachronic

identity.

But

how

is

the demand

for

a criterion

of

synchronic

identity

to

be

expressed

if the

notion

of

identity

is not to be

used?

Once

again,

if the

four-dimensional

ontology

is

presupposed

the

answer

is

simple,

as we

have seen. But

what

if it

is

not?

Then,

I suggest, the only intelligible question to be asked is: What are

the

necessary

conditions

for a

K's

existence

at a

time?

That

is,

what conditions

C

satisfy

the

following

schema:

(3)

Necessarily,

for

any

K,x,

for

any

time

t,

if

x exists at

t,

then

Cx

at

t.

Anything

sensible that

can be said

in answer to

the

request

for

a

criterion

of

synchronic identity

for

Ks

must therefore

be

comprised in the answer to this question.

Of

course,

one

such

necessary

condition

is that

x be

a K. So

there

is

no

hope,

unless we

presuppose

the

four-dimensional

ontology,

of

treating

the

request

for a

criterion

of

synchronic

identity

for

Ks

as

wholly

distinct

from

the

request

for

a criterion

of

diachronic

identity.

But it

may

nonetheless

be

possible,

by

suitable choice

of'C' in

(3)

to

give

an

informative

specification

of







86

II-HAROLD

W.

NOONAN

some

necessary

conditions

of

K-hood

without

thereby specifying

or

presupposing

the

diachronic

criterion of

K-hood.

Many

such

necessary

conditions will

have

nothing

in

common

with

what

philosophers

typically

have

in

mind when

they

talk of

the

criterion

for

the

synchronic

identity

of

Ks,

but this need not be

true of all of them.

A

subset of

such

necessary

conditions,

in the

case of

spatially

extended

objects,

for

example,

will concern the

interrelations of their

(spatial)

parts,

and

when

we

ask for

a

criterion of

synchronic

identity

for,

say, ships

or

tables,

it is

largely

information about this that we are

seeking

(see

once

again

Perry

1972).

In

the

case of

persons

our

interest

in

a

criterion

of

synchronic

identity

is

rather an interest

in

the

relationships

which

must

obtain

between

simultaneously

occur-

ring, co-personal,

mental

states. But

this can

similarly

be

understood as an

interest in

the

truth-yielding specifications

of

(3),

with 'K'

read as

'person'.

But

what now of

what

Lowe calls the exclusion

principle

or

Ks,

the principle that two Ks cannot occupy the same place at the

same

time,

i.e. that

Ks

occupying

the same

place

at the same

time

must be

the

same?

Such a

principle

cannot be

regarded

as

specifying

necessary

conditions

of

K-hood

in the

manner

of an

instance of schema

(3),

yet

it

seems,

at

first

sight,

a

perfectly

intelligible

thesis about

K-identity

at

a time.

How,

then,

can

this

be

reconciled

with

the

Quinean

thesis

that all

questions

about

criteria of

identity,

whether

diachronic or

synchronic,

for

things

of a particularkind must reduce to questionsabout the criteria

for

membership

in

that

kind?

The

easiest

way

to

understand the role of such exclusion

principles,

I

think,

is

to

revert

yet again

to the

point

of

view of

the

four-dimensional

theorist. From this

point

of view there

is,

of

course,

no

difficulty

whatsoever

in

the idea of two

physical

bjects

being

in the same

place

at the same

time. So

what,

from

this

point

of

view,

can

we be

doing

when we

say

(using

the

concept

of

a familiar kind of physical object): two Kscannot occupy the

same

place

at the same

time? The

answer

is that

even

though

we

are not

specifying

a

necessary

condition of K-hood

(a Fregean

'mark' of the

concept)

we

are

specifying

a constraint on

the

concept

of

a

K:

a condition

any

concept

must

satisfy

if it

is to

qualify

as the

concept

of

a K

(or

equivalently,

a

condition

the

unity

relation

for Ks

must

satisfy).

And,

of

course,

the role of

the







SUBSTANCE,

DENTITYAND TIME 87

principle

remains

the

same even

if

the four-dimensional

point

of

view

is

rejected.

But,

if

this is

the

way

in

which exclusion

principles

are to

be

understood,

we can

reaffirm he

Quinean

thesisof

the

reducibility

of

questions

about

identity

criteria

to

questions

about

kind-

membership.

For,

if

this is

the

case,

for

any

kind

K,

whether

the

exclusion

principle

for

Ks

is true

will

be determined

once

the

necessary

and sufficient

conditions

for

membership

in

the

kind

(the

marks

of

the

concept

K)

have been fixed:

if

true its status

will

thus be that of a

merely

derivativetruth which does not have to

be mentioned in

a

full

account of

the

concept

(cf.

the

way

in

which

the

specification

of the

marksof

K-hood,

together

with the

facts,

will

determine,

without

the

aid,

or

the

possibility,

of

any

further

delimitation of the

concept,

the truth-value

of'Ks

exist').

Whether,

once

this

is

accepted,

one

continues

to

speak

of the

exclusion

principle

forKs

(for

those

kinds for

which the

exclusion

principles

are

true)

as

an

aspect

of the conditions

of

K-identity

at

a time is, of course, a matter of no importance. But it is

important,

if

we choose

to

do

so,

to note

the difference

between

this

aspect

of

the conditions

of

K-identity

at

a

time

and

those

which

can

be subsumed under

a

specification

of

the

conditions

C

satisfying

schema

(3);

and to be aware

also

that

it will

be

impossible

to

specify

the marks of

the

concept

of

a

K

which

determine the truth

of

the exclusion

principle

without

specifying

the diachronic riterion

of

K-hood.

(Here,

I

think,

I

am

in

complete agreement with Lowe.)

I

now wish

to

note two

additional

points.

The first of these is

simply

that

one

who

rejects

the four-

dimensional

ontology

but

accepts

the framework

for discussion

outlined

above

can

nonetheless

still mimic four-dimensional

terminology.

He

can,

for

example,

speak

of

an ordered

pair

<x,t>,

where

x

is

a

K

and

t

a time at

which

x

exists,

as a

'K-stage'.

Lowe

refers

to,

and

criticises,

philosophers

who use

the

'thing-

stage' terminologymore generallythan he proposes,but it may

be

that

these

philosophers

have

something

like

this

framework

n

mind when

they

do

so,

and if so their

terminology

is harmless.

My

second

point

is

more

important.

I

have

alreadyemphasized

that

one of the

featuresof

the

four-dimensional

scheme

is

that

it

entails

that

the

familiar

continuantsof

our

everyday

acquaintance

are

a mere subset of the

totality

of

physical

objects,

ontologically







88

II-HAROLD W. NOONAN

on

a

par

with

the

rest,

and

assigned

a

favoured

position

n

our

language

and

conceptual

scheme

only

becauseof interest-

relative considerations.But

this is

certainly

one

reason

why

some

philosophers

re reluctant o

accept

he

four-dimensional

scheme.2

My point

now

s

that

fsomeone

does

object

o the four-

dimensional

cheme

or this

reason,

he

ought

to

thinkno better

of the

alternative ramework

ust

outlined.

For

like the

four-

dimensional

cheme

t

entails he

(possible)

xistence

f farmore

physical

objects

han

are

recognised

n our

everyday

onceptual

scheme,and like the four-dimensionalchemeit entailsthat

theseadditional

ntitiesare

ontologically

n a

par

withthe more

familiar

nhabitants

f

our

conceptual

cheme-or

at

least

with

those

for which it

is

possible

o

specify

nformative

iachronic

criteriaof

kind-membership.

The

reason

orthis

s

very

simple.

To

say

that

a condition

C

is

a

necessary

ut

insufficient

ondition

or

being

a

K

is to

say

that

it is

at

least

possible

or

something

o

satisfy

C

without

being

a K.

So ifthereareseveralecessaryonditions fK-hooddentifiable

by

appropriate pecifications

f R

in

schema

(1)

(as

there

must

be

if

an

informative

iachronic

riterion

fK-hood

s

specifiable

t

all)

then

for

each

such

condition

t must

be

possible

orthere

o

be

objects

other

hanKs

satisfying

t. But

such

objects,

nsofar s

they

can

satisfy

the condition n

question,

and

assuming

he

condition

s

not

one

which

can

be satisfied

by

both

abstract nd

concrete

objects,

must be

concrete

objects

if Ks are

concrete

objects, and thus ontologically on a par with Ks.

For

example,

suppose

it is

held,

to revert

to the familiar

terminology

for a

moment,

that

the criterion

of diachronic

personal

identity

is

physical

continuity

together

ith

psychological

continuity-psychological

continuity

and

physical

continuity

by

themselves

only

being

necessary

conditions.

Then as

I

understand

it,

that

is

to

say

that

physical

continuity

is

only

a

necessary

condition

of

personhood,

which is

to

say,

in

turn,

that

it is at least possible for there to be something

which is not

a

2

Here

I

particularly

have

in mind S. Shoemaker.

In

fact

it was

from

Shoemaker's

1984,

in

which he

expresses

his

objection

to the

four-dimensional

scheme,

that I

got

the

expression

'ontologically

on

a

par'.

Shoemaker

does

not define

it,

but

I

am

taking

it

that

it is a

sufficient

condition

for

Ks

and

A*s

being

ontologically

on

a

par

that

they

are both

kinds

of

concrete

object,

and

it is a

sufficient

condition

for Ks

having

ontological priority

over

A*s

that

A*s

are set-theoretical

constructions

out of Ks.







SUBSTANCE,

IDENTITY

AND TIME 89

person (because

not

psychologically continuous)

which

is

physically

continuous

throughout

its existence.

Equally,

it is to

say

that

psychological

ontinuity

is

only

a

necessary

condition

of

personhood,

which

is to

say,

in

turn,

that it is at least

possible

for

there to be

something

which

is

not a

person

(because

not

physically

continuous)

which

is

psychologically

continuous

throughout

its

existence. But

only

a

subject

of

mental

states

can

exhibit

psychological

continuity,

and

only

a concrete

object

can

be

a

subject

of

mental

states.

The

proponent

of

physical-cum-psychological

continuity

as

the criterion of

diachronic

personal

identity

might

not

have

thought

himself committed

to the

possibility

of

non-personal

physically

discontinuous

subjects

of

mental

states,

but on

my

interpretation

of his

proposal,

just

as

much

as

on

the four-

dimensional

interpretation

(on

which

he

will be

regarded

as

proposing

an

account

of

the

'unity

relation'

for

persons),

he

is.

To

put

the

point

somewhat

differently:

the

proponent

of

physical-cum-psychologicalcontinuity as the criterion of dia-

chronic

personal

identity

will of course hold

that

in

such

cases

of

'mind-swapping'

(information

transfer)

as are

described

in

Williams

1970,

personal

identity

will

not obtain

between

the

A

body

person

before

the

mind-swap

and

the

B-body

person

afterwards.But

if he

interpretspsychological

continuity

in such

a

way

that he claims

that

these

cases

are

counterexamples

o

the

proposal

that

psychological

continuity

is

a

sufficient

condition

of

personal identity over time then he is committed, as I

understand

his

position,

to the claim

that

there

is

present

in

the

case,

in

addition

to

various

physically

(and

psychologically)

continuous

persons,

two other

physically

discontinuous

but

psychologically

continuous

subjects

of

mental

states.

The

proponent

of

physical-cum-psychological

continuity

as

the

criterion

of

diachronic

personal

identity might

not

have

thought

that he

was

so

committed,

but on

my

interpretation

of

his

proposal,just as on the four-dimensionalinterpretation,he is.

The

same

point

holds,

mutatis

mutandis,

hatever

the

concept

for

which

a

criterion of

diachronic

identity

is

being proposed

and

whatever the

specific

content

of the

proposal.

To hold

that

informative

criteria

of diachronic

identity

can be

given

for

the

kinds

of

persisting

things

which

we

talk and

think

about

in our

everyday

lives,

is

to

be

committed,

on

my interpretation

of

what







90

II-HAROLD

W. NOONAN

the

request

for such a

criterion

comes

to,just

as much

as

on the

four-dimensionaltheorist's

interpretation

of that

request,

to

the

possibility

(and,

therefore,

if

the facts are so

disposed,

to the

actuality)

of a

host

of

entities not

acknowledged

in

our

everyday

thought

and

talk.3

Having

explained

my

favoured framework

for

the discussion

of so-called

problems

of

diachronic

and

synchronic

dentity

I

can

now

introduce

the first

sense

which

I

can

give

to the

notion

of

ungrounded

identity

over time.

I

shall refer

to this as

ungroundednessI.

The

identity

over

time

of

persisting

things

of

a kind

K will

be

ungrounded1,

then,

if

no informative

diachronic

criterion

of

K-hood

can be

given.

Now,

of

course,

it is

not

excluded

that the

specification

of an

informative

diachronic

criterion of K-hood

might

require

the

use of the

concept

of some other

kind

of

persisting

hing,

K*.

But

on

pain

of

vicious

regress,

this cannot

always

be so. So

either

there are kinds of persisting things whose identity over time is

ungrounded1,

or

else

there

are some

kinds

of

persisting

hings

for

which

diachronic criteria of

kind-membership

can

be

specified

without the

use

of

the

concept

of

any (other)

kind

of

persisting

thing.

But

if

this

is

so,

and

if

informative diachronic

criteria

of

kind-membership

can be

specified

for

every

kind

of

persisting

thing,

there

will be a

clear sense

in which both

the

concept

of

a

persisting

thing,

and

concepts

of

particular

kinds

of

persisting

thing, are redundant.All facts about persisting hingswillsuper-

vene

on

facts

specifiable

without

the use

of

any

such

concept.

Now

in

Kripke's unpublished,

but

much

discussed,

lectures

on

identity,

he

introduces

the

notion of

a

'holographic

state'

of

the

universe

at a

moment,

a sort of three-dimensional

picture

of

the

universe as

it

is at

a

moment.4

The

important

thing

about

this notion is that the

holographic

state

of

the universe

at

any

instant

is

to

give

us the

complete

state

of the

universe

at that

instant withoutprejudice o whether uccessiveholographs reshowing

3

Though

I

must add that as

far as

I

can see

not

everyQuinean

physical

object

will have

to be

acknowledged

as

a

real

(and

concrete)

entity;

for

example,

this will not

be

so

for

that

Quinean physical object

composed

of a

momentary stage

of

a silver dollar

in

1976

and the Eiffel

Tower

through

its third

decade.

4

For

those who

do

not know

Kripke's

lectures

the

best

source

of information

about

them

is

Shoemaker

1984.







SUBSTANCE,

DENTITY

AND TIME

91

the

ame

r

differentbjects.

he

holographic

state of

the

universe

at

an instant is to be

thought

of as

providing

all the

information

there

is

about the

state

of

the

universe,

and

the

properties

of its

inhabitants,

at that

instant,

but not information about their

numerical

identity

with,

or

numerical distinctness

from,

items

depicted

in

earlier

or

later

holographs.

Now it

would

be

a

sufficient

condition

of the

redundancy

of

any

concept

of a

persisting

thing,

and hence a sufficient

condition for all

identity

over time

to

be

groundedl,

if

there

were

no facts about the universe 'over and above' facts about its

holographic

states,

i.e. if

the

totality

of

facts about

the universe

supervened

on the

totality

of

facts

given

by

its

holographic

states.

Let us call

this

'the

strong

holographic

supervenience

thesis'.

But

even if the

strong holographic

supervenience

thesis is

false,

identity

over

time

may

still

always

be

grounded,.

For all

that this

requires

is

a

weaker

supervenience

thesis,

namely

that

the

totality

of

facts about the

universe

supervene

on

the

totality

of facts given by its holographic states together ith thoseof their

relationships

which

may

nclude

.g.

causal

dependencies)

hich

can

be

specified

without

employing

he

concept

f

a

persisting

hing.

This is a

weaker thesis

because

there

may

be

relationships

between

holographic

states

specifiable,

without

the

use

of the

concept

of

a

persisting thing,

which

do not

supervene

on

the

totality

of

facts

given

by

those

holographic

states.

I

shall call

this

second

supervenience

thesis

'the weak

holographic supervenience thesis'. Identity over time is un-

grounded1

if,

but

only

if,

it is

false.

I

return

to this

question

in

section

V.

IV

There

is

another

line of solution to

the

puzzle

I

outlined

in

section

II, however,

which

has also

had an influence on

the

discussionof

problems

of

identity

over time. We

can call

this,

for

brevity, but somewhat misleadingly, the Fregean solution.

According

to

Frege's

familiar

proposal

we can

introduce

the

functor

'the

direction of'

by

the

stipulation

that:

the

direction of a

=

the

direction of

b

iff

a is

parallel

to b.

We

thereby

fix

the

criterion of

identity

for directions

as the

relation of

parallelism

between

lines.







92

II-HAROLD

W. NOONAN

With this

fixed we

can

go

on to

explain

'x

is a direction'

as

meaning

'for

some

line

a,

x is

the direction

of

a',sand

we

can

go

on

to

explain

the

predicates

of

directions

in terms

of

those

satisfiable

by

lines,

subject

to the constraint

that the truth-

conditions of each

statement of the form

'the

direction of

a

is F'

be

given by

a

statement

of

the form

'line a

is

PF',

where

'F*'

denotes

a

property

of lines for which

parallelism

s

a

congruence

relation.

Thus,

starting

from

a

specification

of the criterion

of

identity

for

directions we can

go

on to

explain

the

whole

'language

game'

in which we

speak

of directions.

This

approach

is

susceptible

to

generalization.

For

any

kind

of

object

K

we can ask

(although

we cannot

always

receive

an

answer):

(i)

what

entities

play

the role

for Ks

that

straight

lines

play

for

directions,

and

(ii)

what

relation

plays

the role

for

Ks

that

parallelism

plays

for

directions?

We

can

apply

this

Fregean approach

to

problems

of

diachronic

identity

and we can

do

so without

presupposing

the

Quinean four-dimensionalscheme.' The entitieswhich standto

Ks

as

straight

lines

stand

to

directions

might

be ordered

pairs

of

persisting things

(of

a

distinct

kind

K*)

and

times,

and

the

relation

which

serves as the criterion of diachronic

identity

for

Ks

might

be a

relation between

pairs

of such ordered

pairs.

Where a

and

b

are

A*s

the

criterion of

diachronic

identity

for

Ks

could then be

given

in

the form:

the

Kof

which

K*a

is a

manifestation

at

t

=

the

Kof

which

K'*b

s

a manifestation

at

t' iff

<a,t>R<b,t'>.

5

At

this

point,

of

course,

Frege

himself

proceeded

differently,

explicitly

defining

directions

as

classes

of

parallel

lines

(or

rather,

as

the

extensions

of

certain

concepts).

This

is

why

I

warned that it

was

somewhat

misleading

to describe

the

approach

outlined

in

the

text

as

'Fregean'.

However

(apart

from the fact that

the

problem

which

causes

Frege

to take

this

line

(The

'Caesar'

problem)

is

not solved

by

it,

but

only pushed

further

back)

if

we were to

be

faithful to

Frege

here

it

would

appear

completely

implausible

to

suppose

that the

Fregean

approach

could have

application

to

any problems

of

identity

apart

from

those for

types

of abstract

bject.

For

a

good

discussion

of

Frege's

views on

these

matters,

to which this section is

heavily indebted see Wright

1983.

6But

what is the

relation of this

approach

to

problems

of

diachronic

identity

to

the

approach

outlined

in

the

previous

section?

The

answer,

I

think,

is

that

the

Fregean

approach

is

just

another

way

of

developing

the

Quinean

insight

that

questions

about

identity

criteria reduce

to

questions

about

kind-membership;

n

specifying

the

Fregean

criterion

of

identity

for directions

one is

specifying

exactly

what it is to be

a

direction,

namely something

for which

questions

of

identity

and

distinctness

are

reducible

to

questions

of

parallelism

between

lines. That is all there is to

being

a

direction

(see

again

Wright

1983).







SUBSTANCE,

DENTITYAND TIME

93

Being

a

K

could

then

be

explained

as

being

the K

of

which

some

<a,t>

is the

manifestation,

and

the

satisfactionconditionsof

predicates

satisfiable

by

Ks could be

explained

in terms of the

properties possessed

by

K*s

at

times

(equivalently,

relations

between

K*s

and

times,

or

properties

of

ordered

pairs

off*s

and

times).

Thus,

if

one is

prepared

to

discount

the

possibility

of

disembodied

existence,

one

might

take

the

problem

of

diachronic

personal

identity

to be the

problem

of

specifying

the

relation

which

body

a

existing

at time

t

must bear to

body

b

existing

at

time

t',

iff the

person

occupying

a at

t is

to

be identical

with

the

person

occupying

b

at t'. Here

the

K*s

are

bodies.

Or,

if

one

finds the idea

of

a

Lockean

thinking

substance

intelligible,

one

might

take

it to be the

problem

of

specifying

the

relation which

thinking

substance

a,

existing

at

time

t,

must bear

to

thinking

substance

b,

existing

at time

t'

iffthe

person

in which

a

thinks

at

t is

to be

identical

with

the

person

in which

b

thinks

at

t'. Here the K*s are thinking substances.

But

although

the

Fregean

approach

can

be

applied

to

problems

of

diachronic

identity

without

presupposing

the four-

dimensional

scheme,

it is

not,

of

course,

incompatible

with

it;

so

one

might

also

take the

problem

to be

that

of

specifying

the

relation

which

must

hold between

person-stage

a,

existing

at

t,

and

person-stage

b,

existing

at

t'

iff

the

person

of which

a is a

stage

at

t

is to

be

identical with the

person

of which b is

a

stage

at

t'. Here the K*s are person-stages,and if they are momentary

the

reference

to

times is

redundant.

The

Fregean

approach,

then,

provides

a second

way

of

making

unproblematic

sense of

requests

for

criteria

of

diachronic

identity.

But

it

should be noted that

it,

too,

requires

the

recognition,

as

ontologically

on a

par

with

the

familiar

things

of

our

everyday

acquaintance,

of a multitude of extra

entities

which

go

unremarked

in

our

everyday

thought

and talk.

For

if

the criterion of diachronic identity for a familiar kind of

continuant

K

is

given

as

an

equivalence

relation

R,

between

ordered

pairs

of

K*s

and times there

will

be

equivalence

relations entailed

by

R,

or

entailing

R,

equally capable

of

serving

as

criteria of

diachronic

identity.

And

if the

availability

of a

criterion

of

diachronic

identity

for Ks in

terms of

K*s

does

not

oblige

us to

regard

Ks

as set-theoretical constructions

out

of







94

II-HAROLD

W. NOONAN

K*s

(in

which

case,

as

noted in

footnote

5,

the

Fregean approach

to

problems

of diachronic

identity

becomes

completely implaus-

ible)

then we

are no more

obliged

to

regard

the unfamiliar

entities for which

these latter

relations

can serve

as criteria

of

diachronic

identity

as

set-theoretic constructions

out

of

K*s.

There

will

thus be

no

reason

not to

regard

them as

ontologically

entirely

on

a

par

with

Ks,

albeit of

less

interest to

non-

philosophers.

Now

I

can

introduce

a

second

sense

I

can

give

to the

notion of

ungrounded

identity

over

time-ungroundedness2.

The

identity

of Ks over time will be

ungrounded2

iff

no

Fregean

criterion

of diachronic

identity

for

Ks

can

be

given.

Now

I

said above that

the

applicability

of the

Fregean

approach

to

problems

of

diachronic

identity

did

not

require

the

four-dimensional

framework, but,

of

course,

on

pain

of

vicious

regress,

if

Fregean

criteria

of

diachronic

identity

are to be

available

for

all

kinds

of

persisting

thing,

there

must

be

a

class of

non-persisting things to relations between which the identity

over time

of

at least

some of

these

things

reduces.

Thus it

will

be

a

sufficient

condition

of

identity

over time

being

ungrounded2

that

such a class

of

non-persisting things

does not

exist.

But

even

if

this

is

so,

it is

to

be

noted,

it

will

not

immediately

follow

that

identity

over

time

is

ever

ungroundedl.

This

could

only

be so if

the

weak

holographic supervenience

thesis

entailed

the existence of such a class of non-persistingthings, and it is

unclear that it

does so.

V

In his

unpublished

lectures

Kripke

argues explicitly

against

the

strong

holographic

supervenience

thesis,

and

perhaps

against

the weak


thesis

also. Thus his

arguments

present

a

challenge

to

the

thesis

that

identity

over

time is never ungrounded1, and Kripke does explicitly take

himself to

be

arguing

for a

sense in

which

identity

over time

is

to

be

regarded

as a

primitive

or

ungrounded

fact.

In

this

section

I

wish

to

explain

why

Kripke's

argument

does

not convince

me

that

identity

is

ever

ungrounded1.

I

should

add,

however,

that

my

rejection

of

Kripke's argument

is

very

tentative,

for,

as will

emerge,

there

is

a substantial

price

to

be







SUBSTANCE,

DENTITY

AND TIME

95

paid

for its

rejection,

and whether that

price

is worth

paying

is

debatable.

Kripke's

argument

(for

which those who do

not

know

Kripke's

lectures should

consult Shoemaker

1984)

concerns

a

homogeneous

disc,

stationary

in

one

world,

rotating

in

a second.

The

identity

of

the disc is not in

question,

but

consider

the

portion

of

matter which

makes

up

its

northern half

at some

time

t: if the

disc

is

stationary

this

will

be

the same

portion

as

makes

up

its

northern half at

any

later

time

t'.

Not

so

if

the

disc is

rotating.

Thus the two worlds will differ with

respect

to what identities

hold

over

time,

and hence with

respect

to

facts

statable

in

the

form

'Some

portion

of

matter

is

in P

at

t

and

P'

at

t".

If then

they

do not

differ

in

their

holographic

states

the two worlds

are a

counter-example

to the

strong


thesis,

and

if

they

differ neithern their

holographic

states

nor

n

the relations

between those states

which are

specifiable

without

the use

of

the

concept

of a

persisting

thing

they

are a counter-

example to the weak holographic supervenience thesis-and

hence a

proof

that

identity

over time

is sometimes

ungrounded1.

Kripke

certainly

takes his

disc

example

to

play

the

first

of

these

roles,

and he

may

take

it to

play

the second.

However,

I

am

unconvinced.

First,

it has

to

be

emphasized

that

for

Kripke's

example

to

work

the

two

worlds must differ not

at all

in

their

momentary

holographic

states;

it is

not

enough

that

they

exhibit

no such

difference locally, i.e. no such difference where the disc is

located.

Nor is

it

enough

that

they

exhibit

no

such

difference

whilst

the disc is in

existence. For

either

holographic super-

venience

thesis

to be

refuted

by

the

example

the

two worlds

must

differ

not

at

all,

anywhere,

anytime,

in

respect

of

their

momentary

holographic

states. For

to

refute

a

supervenience

thesis one must

describe two

possibilities

differing

not at

all

in

respect

of

the

proposed

supervenience

base,

but

differing

in

supposedly supervening facts.

This

point,

I

think,

puts

Kripke's

example

in

a

ratherdifferent

light

from

that in

which

it

initially appears.

At first

sight

the

example

seems

perfectly commonplace-one

simply

imagines

the

disc and notes that it will look

exactly

the same

in each

momentary holograph

whether

it is

spinning

or

not. But

this

is

to

ignore

the

point

of

the

previous paragraph,

and

once that is







96

II-HAROLD

W.

NOONAN

taken into account

it

becomes clear that the

example

is

a

good

deal less

ordinary

than it

might

at

first

sight

have

appeared.

It

is

no

good

for

instance

to

think

of

the disc as set in motion

in

world

1

(the

world

in

which

it

rotates) by

someone's

giving

it a

twist.

For

if

this

happens

in

world

1

but not

world

2

the

two

worlds

will

differ

with

respect

to their

holographic

states

before

the disc is

set

spinning.

Either

the disc

is

always spinning

in

world

1,

then,

or it

came

into

existence

spinning

there,

or

its

spinning

was

started

by

a

cause

which

was

not

present

in

world

2

but whose

absence

from that world makes its

holographic

statesno different from

those

in world

1.

I

do not

say

that

these

points

prove

the

unintelligibility

of

Kripke's example,

but

only

that

they

make

it

clear that

it should

not be

treated as

wholly

uncontentious.7

If

the

example

is

accepted

as an

intelligible

one,

however,

it

does

refute

the

strong

holographic

supervenience

thesis,

and

since,

despite

the

words of

cautionjust

given,

I

do not feel

able to

deny its intelligibility, I accept that that thesis is refuted.But

what matters from the

point

of view of

this

paper

is whether

Kripke's

disc also

refutes

the

weak


thesis,

and

that I

am not

prepared

to

admit.

For

even

if

the

existence

of two

worlds

related as

Kripke

requires

if

the

strong

holographic

supervenience

thesis

is

to

be

refuted has

to

be

admitted,

these two worlds

must still

differ

in

respect

of

the

counterfactuals

true of the relations

which obtain

between theirholographicstates. Forexample in world2, where

the disc is

stationary,

it

will

be

true

that

if its

northern

half had

been marked

in

a

certain

way

at a time t then its

northern

half

would have

had

that mark

on

it at a

subsequent

time

t',

whereas

in

world

1,

where the

disc is

spinning

this

will not be so

(assuming

'

is

sufficiently

ater

than

t);

but other counterfactuals

will

be

true,

e.g.

that if

the

northern half of

the

disc

had been

marked

in

a certain

way

at t its southern half would

have

exhibited that mark at t' (cf. Shoemaker 1984:224).

If,

then,

these

counterfactuals

can

be stated without

the

'7

f,

that

is,

its

purpose

s

to refuteone of the

holographic

upervenience

heses,

but

it

can

be

treated as

wholly

uncontentious

if it is taken

(as

Kripke

also

takes

it)

as a

counter-

example

to the

thesis

that

spatio-temporal continuity

(under

a

sortal)

suffices

for

transtemporal identity,

for

then

it

does not

require

that

worlds I and 2

be

globally

indistinguishable

in

respect

of their

holographic

states.







SUBSTANCE,

IDENTITY

AND TIME

97

employment

of

the

concept

of a

persisting thing

the

two

worlds

will

not

be related

in

such

a

way

as to refute

the weak

holographic

supervenience

thesis,

or

to establish

the existence

of

identities which

are

ungrounded,.

But

it

does

seem that these

counterfactuals

can

be

stated

in

this

way.

(Of

course,

as

actually

stated

they

presuppose

the

identity

over

time

of the whole

disc,

but that

is

irrelevant.)

There

is

a natural

counter

to this

argument,

however,

which

is

to

point

out that if

the

weak

holographic

supervenience

thesis

is to be maintained in this

way

in the face of

Kripke's

disc

example

(while

the

strong holographic

supervenience

thesis is

acknowledged

to be

refuted

by

that

example)

then

the

counterfactuals

in

respect

of

which the

two

worlds

differ

must

be

accepted

as

barely

rue. For

they

cannot

be true

in

virtue

of

differences

in the

two worlds'

holographic

states-there

are

none.

Nor can

they

be

true

in

virtue

of the

facts about

identity

over

time

in

respect

of which the

two

worlds

differ-for these

latter differencesare supposedto obtain, accordingto the weak

holographic

supervenience

thesis,

because

f

the

difference

in

counterfactuals,

not the

other

way

round.

(The

same

point

can

be

approached

by

recalling

the

point

of

insistence on

the weak


thesis,

namely,

to

enable

retention

of

the

thesis

that

identity

over

time

is

always

grounded1,

i.e.

that

there

is

no kind

of

persisting

thing

for

which a diachronic

criterion

of kind

membership

can

not

be

given.

But

if

reference

to counterfactual relations between momentary holographic

states

has

to enter

into an

account of what

it is

to

be a

K,

the

obtaining

of

such

counterfactual relations

can

hardly

be

explained

as

grounded

in

the existence

of a

K.)

It was this

counter-argument

that

I had

in

mind

when

I

said

earlier

that a

high

price

had

to

be

paid

for resistanceto

Kripke's

argument-the

price

is

the

acceptance

of

the

possibility

of

barely

true

counterfactuals.

I am not, however,convinced that the priceistoo highto pay.

For the

alternative

is

to

postulate

as

the

grounds

of

the

counterfactuals facts

about

identity

over

time which ex

hypothesi

cannot be

grounded

in

anything

else.

But

our

understanding

of

what it is

for these

identities to

obtain

and

to differ

between

the

two

worlds

is

mediated

only

by

our

understanding

of

the

counterfactuals

which

obtain there.

So

it is

unclear

that







98

II-HAROLD

W. NOONAN

postulation

of

the

identity

facts

can

be

anything

other

than

a

way

of

preserving

the letter of

the

thesis that

counterfactuals

cannot be

barely

true.

I

conclude,

albeit

tentatively,

that

Kripke's

disc

example

does

not

prove

that

identity

over

time

is ever

ungrounded,--though

it

does

prove (assuming

that it

refutes

the

strong

holographic

supervenience

thesis)

that either

his

is

so or counterfactuals

can

be

barely

true.

There

is a

final

point

to be made about

Kripke's

argument,

however: even if it should be

accepted

without reservationsit

does

not

entail

that

the mere

asking

of

questions

about

diachronic

identity

criteria

(as

such

questions

are

interpreted

n

section

III)

is

illegitimate.

For even

if it does

establish

that

identity

over time

may

sometimes

be

ungrounded1,

t establishes

this

only

for entities

of

a

very

special

kind-homogeneous

masses

of

matter

which

(at

some

time

in their

existence)

are

proper

parts

of

larger

masses of the

same kind

of

homogeneous

matter.

And it is unclear that reference to entities of these kindswould

ever

be

required

in an

account

of

the criteria of

diachronic

identity (diachronic

criteria of

kind

membership)

of

the kinds

of

entity

that

our more

familiar sortal

terms

signify.

But

if

not

then

even

if

Kripke's argument

is

wholly

correct

it leaves

a

very

large

area

within which

queries

about

criteria

of diachronic

identity

are

entirely

legitimate.

VI

Jonathan

Lowe's own

argument

for

ungrounded

identity

is

different

from

Kripke's

and

it is

unclear

how,

even

if

it

is

valid,

it

can refute the

(weak)

holographic

supervenience

thesis.

(It

does

not

present

us,

as

Kripke's

argument

does,

with a

pair

of

possible

worlds identical in

the

supposed

supervenience

base

but

differing

in

the

allegedly

supervening

facts.)

Consequently,

I

cannot see that it establishesthe existenceof identitieswhich are

ungrounded1.

But

that,

I

think,

is not

its

aim.

Rather

its

aim

is

to

refute the idea that a class

of

non-persisting

entities

exists,

to

relations between which the existence of

persisting

things

reduces.

That this is so

is,

of

course,

part

and

parcel

of

the

four-

dimensional

picture,

and

is

also

entailed

by

the

thesis

that

identity

over

time

is

never

ungrounded2,

i.e.

that

Fregean







SUBSTANCE,

DENTITY

AND

TIME

99

criteria

of

diachronic

identity

can be

given

for

all

persisting

things.

If

the

idea he

objects

to

were

correct,

Lowe

argues,

everything's

persistence

would

ultimately

be accounted

for

by

reference

to

change.

But the

very

notion

of a

change presupposes

that of

the

persistence

of at

least

somethinghrough

that

change

and so

cannot

be

appealed

to in

giving

a

perfectly

general

account

of

what the

persistence

of

objects

consists n. The

persistence

of at

least some ort of

thing

must

thus

be

primitive

or

ungrounded

in

that it consists neither in

relationships

between

non-persisting

things,

nor

in

the

persistence

of

other

sorts of

things.

I

agree

with

part

of

this. It

does

seem

right

to

say,

and

Lowe

seems to

argue

effectively,

that

the notion

of

change

is

bound

up

with the

notion of

persistence.

If

there

is

to be

change

there

must

be that which

persists

through

the

change.

For

if

nothing

persisted through

the

change,

then,

as

Lowe

says,

with

what

right

could we

regard

the

events

occurring

before

the

change

as

belonging to the same possibleworldas theeventssubsequentto

it? And how

then

could we

regard

the

change

as a

change?

For

if

nothing

persists

it is

not

a

change

in

anything,

but

at best

a

change

in

how

things

are

in

(what

features

are

present

at)

a

certain

spatial

location.

But in the

absence of

any

framework

of

persisting

objects

how

can

we make sense of

the same

spatial

location

first

exhibiting

one feature and then another?

I

agree

with

Lowe

then

that the

hypothesis

of a

global

existence-change

is incoherent: ifa possibleworldisone inwhich thereischange it

is also

one

in

which

there

are

persisting

hings (not

necessarily,

as

Lowe

points

out

(footnote

12)

to

be

picked

out

by

count

nouns)

which

provide

the

background

to

change.

But

to

say

this is

only

to

say

that the

applicability

of

the notion

of

change

to

a

possible

world entails

the

applicability

of the

notion

of

persistence,

and

that,

as far as

I can

see,

is

quite

compatible

with

the

four-dimensional

scheme,

or

with the thesis

that Fregean criteria of diachronic identity are available for all

persisting things.

What

does

follow,

if

either of

these

is

correct,

is

that whenever

anything

persists,

omething

lseceases

to

exist,

and

something

lse

comes into existence.

But

that

is

not

to

say

that

really

nothing

persists

(cf.

the

well-known

objection

to

Lewisian

Counterpart

Theory

that

it

entails

that

really

all

properties

are

essential-it

doesn't).







100

II-HAROLD W.

NOONAN

Thus

I

fail to

see

that this

argument

of

Lowe's

establishes

its

conclusion.s

To sum

up:

I

began

by

presenting

a

puzzle

which seemed

to

cast

doubt

on

the

intelligibility

of

requests

for

criteria

of

diachronic

identity.

I

then

presented

two

responses

to

this

puzzle

and

in

the

light

of them

defined

two senseswhich could

be

given

to

the notion

of

ungrounded

identity

over

time.

I

argued,

however,

albeit

tentatively,

that

no

proof

of

ungrounded

identity

over time

in

either

sense

had

been

given,

either

by

Kripke

in hisfamous

unpublished

lectureor

by

Lowe. I havenot

claimed,

however,

that no

such

proof

can be

given.

REFERENCES

Brody,

B.,

1980,

Identity

nd

Essence,

Princeton,

Princeton

University

Press.

Lewis,

D.,

1986,

On the

Plurality

of

Worlds,Oxford,

Basil Blackwell.

Perry, J., 1972, 'Can The Self Divide?', TheJournalof Philosophy, 9.

Quine,

W.V.O., 1976,

'Worlds

Away',

The

Journalof

Philosophy,

3.

Shoemaker,

S., 1984,

'Identity,

Properties

and

Causality',

in

Identity,

Causeand

Mind,

Cambridge, Cambridge University

Press.

Swinburne, R., 1976,

'Persons

and Personal

Identity',

in

Contemporary

ritish

Philosophy,

ed. H. D.

Lewis,

London,

George

Allen

and Unwin.

Williams,

B.,

1970,

'The

Self

and

the

Future',

Philosophical

eview,

79.

Wright,

C.,

1983,

Frege'sConception

f

Numbers

s

Objects,

Aberdeen

University

Press.

8Independently

of this

argument

Lowe also

directs some

criticism

at the

four-

dimensional

notion

of a

'thing-stage', arguing

that

even if the

existence of

such entities

is

admitted

they

are

incapable

of

being

identified

independently

of

the

things

of

which

they

are the

stages.

I

lack the

space

to

go

into

this;

but note

that this

will not be

so

if

Lewis's account

of

thing-stages,

more

particularly,

person-stages

mentioned by

Lowe

in

his footnote

6),

is

accepted.

In

fact,

the

argument

of

Lewis's that Lowe

refersto seems

to

me

very powerful (but

one of

its

premisses

s

the weak


thesis

so it is not wholly uncontentious). Lowe objects to its firstpremiss ('First:

it

is

possible

that

a

person-stage

might

exist.

Suppose

it

to

appear

out

of thin air then

vanish

again')

that all

it

does is

to introduce

us

to the fanciful

notion

of a

very

short-lived

person.

But

this is

merely

to draw attention

to

the

fact,

which Lewis

explicitly

acknowledges,

that

person-stages

as he

characterizes

them are entities

it would

be

perfectly

correct

to

describe

as

persons

f

they

were

not

proper parts

of

similarly

characterizable

wholes.

This

does not

entail

that

it

is

correct

to

describe them as

persons

when

they

are

proper parts

of

such

wholes

(though

it

might

be,

as

the

philosophers

referred

o

by

Lowe

in his

footnote

5

claim;

but

this

would not affect the

cogency

of

Lewis's

argument).

substance, identity and time

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