does practical rationality constrain epistemic rationality
TRANSCRIPT
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Does Practical Rationality Constrain Epistemic Rationality?
(Forthcoming in Philosophy and Phenomenological
Researchsymposium on Fantl and McGrath Knowledge in
an Uncertain World)
I The Direct Argument
An issue that looms large in contemporary
epistemology concerns the relationship between knowledge
and practical rationality. Jeremy Fantl and Matt McGrath
provide the most in-depth and rigorous discussion of this
issue. Their book is an impressive achievement and Ilearned much from studying it.
Fantl and McGrath (F&M) defend a general principle
linking knowledge and rational justificationboth practical
and theoretical:
KJ: If you know that p, then p is warranted enough to justify
you in !-ing, for any !. (66)
For F&M, the justification component of knowledge is
carrying the theoretical load. Thus they endorse
JJ: If you are justified in believing that p, then p is warranted
enough to justify you in !-ing, for any !.(99)
While I am unclear about whether KJ is true, I am
inclined to think JJ is false. Most of the discussion of these
issues has centered on cases that pull intuitions in one
direction or the other. To their credit, F&M set out to move
the discussion beyond intuitive judgments about cases.
They construct a principled argument in defense of JJ.
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The direct argument" attempts to derive JJ from
fundamental principles, some of which are analogues of the
principles used in their argument for KJ. The principle I will
focus on is central to the argument for KJ and JJ:
The Unity Thesis: If p is warranted enough to be a reason
you have to believe that q, for any q, then p is warranted
enough to be a reason you have to !, for any !.
It is uncontroversial that theoretical reasons can
constrain practical reasons. But according to the Unity
Thesis, practical reasons can constrain theoretical reasons.
F&M begin by commenting on how we do in fact reason:
"On a hike, you come to a frozen pond. Do you walk across
or walk around the frozen pond? Walking around will take a
while, but you don't want to fall though the ice. How do you
decide? The crucial issue is whether the ice is thick enough
to hold you. Suppose you do some checking (you call the
park authorities) and come to know that the ice is thick
enough. So the ice is thick enough becomes a reason you
have to believe other things (e.g. that it is perfectly safe to
cross it). It would then be very odd not to allow this
knowledge into your practical reasoning" (73-4)
F&M argue that as a matter of fact we do not typically
segregate our reasons for believing and our reasons for
acting. But they concede that, as a psychological matter, it
might be possible to do so, e.g., for you to count the ice is
thick enoughas a reason to believe you will cross safely,
while at the same time not treating the ice is thick enoughas
a reason to cross the ice. In their view, however, segregating
your reasons in this way would be irrational:
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When p becomes available as a basis for theoretical
conclusions, it is 'barmy' to ignore p in one's decision-making
and planning".
While I agree that in general, reasons for believing will
(in the relevant sense) be reasons for acting, matters are
somewhat different when we consider cases with massively
asymmetrical stakes:
Suppose crossing the ice rather than walking around the
pond would save at most a few minutes (and saving the few
minutes counts for almost nothing). Suppose further that the
water is deep enough so that if you break through the ice,
you will certainly drown. When the stakes are so
asymmetrical, the Unity Thesis seems to run into trouble.
Consider the proposition:
Thick: The ice is enough to support your weight.
On the basis of the testimony of the park authorities, is
sufficiently warranted to be a reason you have to believe that
if you cross the ice, it will not break.1But is Thicksufficiently
warranted to be a reason you have to cross? It would seem
not. You have everything to lose, and virtually nothing to
gain. Why risk your life in order to gain a few minutes?2
The preceding strikes me as the correct way to
describe the case. The testimony of the park authorities
makes it rational for you to believe that if you cross, the ice
1If reasons must be true, we can stipulate that is true.2Note that one cannot hold that Thick issufficiently warranted to be a reason you have to
cross, but that it is not a good enough reason to justify crossing. Given the specifications
of the case, Thick is certainly a strong enough reason. Were you certain of Thick, itwould be rational for you to cross. So the problem has to be that it is insufficiently
warranted to be a reason for you to cross.
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will hold you. But the asymmetrical stakes makes it irrational
for you to cross. If so, then the Unity Thesis fails. Of course
F&M would resist this description of the case. They would
agree that Thickis not sufficiently warranted to be a reason
for you to cross. But they would also hold that neither is
Thicksufficiently warranted to be a reason for you to believe
that if you cross, the ice will not break. On their view, it
would be barmy for you to appeal to Thickas a reason to
believe but not to appeal to it as a reason to act. F&M point
out (in correspondence) that the situation as I describe it,
would license your saying (or simply believing) seemingly
crazy things.
To see this, we need to make the familiar distinction
between there being a reason for you to do !, and your
having that reason to do !. In the case we have been
discussing, Thickis a reason for you to cross the ice. This
remains true whether or not you possess Thickas a reason
to cross the ice. On my description of the case, you are
justified in believing Thick. Now suppose, as F&M suggest,
we stipulate that you justifiably believe that Thickis a reason
for you to cross the ice. Finally, if as I hold, Thickis not a
reason you have to cross the ice, then this is something you
could recognize. But that means you could be justified in
believing:
Strange: The ice is thick enough, and that is a reason for me
to cross, but I do not have that reason.
Admittedly, this result is somewhat jarring. How could you be
justified in believing Strange? I will argue that independently
motivated principles about the structure of reasons can
explain how.
Jonathan Weisberg has defended the following
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principle:
No-feedback: If one reasons from premise P to conclusion C
via lemma L, then if p does not by itself support C, the
inference from C to L is unjustified.3
This is a very plausible principle. The main idea is that you
cannot increase the justificatory power of your evidence
simply by making inferences from it.4Suppose your evidence
supports some lemma to just above the threshold for rational
justification. Even if that lemma is a good inductive reason
to believe some further conclusion, inferring the conclusion
from the lemma could result in that conclusion having a level
of justification below the threshold. This means that we
cannot allow that any inductively good inference from a
lemma we justifiably believe yields a justified conclusion.
According to No-Feedback, the conclusion will be justified
only if the original evidence supports it.
Note that as a consequence of No-Feedback, the
following situation could arise. On the basis of some P, you
are justified in believing some lemma L, where L is a reason
to believe C. If you are justified in believing L is a reason to
believe C, then you will be justified in believing L, and that L
is a reason to believe C. But you may still be justified in
believing that you do not have that reason. This is an
epistemic analogue of (Strange). For example, suppose you
justifiably believe, on the basis of the muddy footprints
matching his shoe size, that the butler did it. But the muddy
footprints just barely justify you in believing this. Suppose
further that the butler did it is a good inductive reason to
3Bootstrapping in GeneralPhilosophy and Phenomenological Research 81, 2010. I
have simplified the statement of the principle for current purposes.4Weisberg argues, correctly I think, that the principle blocks bootstrapping reasoning.
Unfortunately, the Dogmatist is committed to rejectingNo-feedback.
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believe that the maid knows who did it. You might
nonetheless fail to be justified in believing that the made
knows who did it. That is to say, you could be justified in
believing
Strange-epistemic: The butler did it, and that is a reason for
me to believe that the maid knows about it. But I do not
have that reason.
You do not have The butler did it as a reason because it is
not sufficiently warranted to justify you in believing that the
maid knows who did it. So when there is epistemic feedback,
one can end up with justification for epistemic analogues of
Strange.5
In No-Feedback, the conclusion C is a belief. But we
also reason to practical conclusions--intentions or actions. I
see no reason why we should not generalize NF to apply to
practical conclusions as well:
Practical No-Feedback: If one reasons from premises P to
an intention to act I via lemma L, then if P does not by itself
support I, then the inference from L to I is unjustified.6
Practical No-Feedbackshould be as plausible as
Theoretical No-Feedback. The point of No-Feedbackis that
if one's initial premise does not support one's practical
conclusion, then neither does any lemma one might infer
from one's initial premise. This remains true whether the
conclusion is a belief inferred directly from the lemma, or
whether it is an intention inferred from the lemma in
5This also demonstrates the failure of F&Ms principle (J
KR for belief) p98
6We can remain neutral on whether the conclusion of a practical inference is an intention
or an action.
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analogues of Strange. I can see no reason to suppose that
you could be justified in believing Strange-epistemic but not
Strange. I conclude that the Unity Thesisis false.
II Outright Belief
My argument against the Unity Thesisraises issues
about the nature of binary or outright belief. On a certain
view of outright belief, my description of the case seems to
be incoherent. F&M call it The Strong Pragmatic View of
belief:
(SPV) You believe that p iff your credence for p is high
enough for p to be your motivating reason for !-ing for all
!.(137)8
A consequence of SPVis that in the asymmetrical stakes
version of the frozen pond case, you fail to outright believe
Thick. Given those stakes, your credence for Thickis not
sufficient to motivate you to cross the ice. And if you do not
believe Thick, you do not justifiably believe Thick.
The issues concerning the nature of outright belief are
too complex for a thorough treatment in this symposium
piece. What I can do is point out a reason to be worried
about the correctness of (SPV). Then I will sketch an
alternative account according to which you do outright
believe Thickin the asymmetrical stakes case.
The reason to be worried about (SPV) is that it has the
consequence that what you believe depends on what you
prefer.9Suppose in the asymmetrical stakes case, I get
7 F&M favor SPV, though they do not explicitly endorse it. They also distinguish it from
what they call weak pragmatic belief.9 Jacob Ross and March Schroeder raise this problem in Belief, Credence, and
Pragmatic EncroachmentPhilosophy and Phenomenological Research, forthcoming.
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depressed and stop caring whether I fall through the ice and
drown.10 According to (SPV), under this scenario I do
outright believe Thick, because my new preference structure
has eliminated the massive asymmetry in the stakes. With
my new preferences, my credence for Thickis high enough
for it to be my motivating reason to cross the ice. I will save
time, and it is no longer a priority for me not to fall through
the ice. So before the change in my preferences, the
strength of my credence was insufficient for me to count as
believing Thick. After the change, even though my credence
for Thickremains unchanged--the strength of my credence
has not increased--I now count as believing Thick. The mere
fact that I have stopped caring so much about whether I
drown entails that I now believe Thick. This strikes me as
extremely implausible.
Now consider the view that part of the functional role of
outright belief is to (defeasibly) dispose one to treat P as true
in ones reasoning.11 On this account, your outright believing
disposes you to treat Thickas true in your reasoning. But
the disposition is defeasible. So while in the normal course of
events, you will treat Thickas true in your reasoning, in
cases where the risk of acting on Thickis too great, this
disposition gets defeated. In these circumstances, you will
treat Thickonly as probable in your reasoning. But the
defeasible disposition remains, even when it is defeated.
Thus, despite the fact that under these circumstances you
are not treating Thickas true in your reasoning, you continue
10 It is not clear to me whether SPVrequire rationalmotivation. If so, and we assume
depression is irrational, we can assume that the preferences change rationally, or at least,
not irrationally.11
Versions of this view have been held by various people, though I borrow this
formulation from Jacob Ross and Mark Schroeder, ibid.
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to outright believe 12
III The Subtraction Argument.
F&Ms` "Subtraction Argument" purports to derive JJ
from KJ. If the Unity Thesis fails, then so does the argument
for KJ. I do however think that KJ is more plausible than JJ
on its own terms. For this reason, it would be of interest if JJ
could be derived from KJ.
The Subtraction Argument has three steps:
(S1) If you know that p, then p is warranted enough to justify
you in !-ing for any !(KJ).
(S2) Holding fixed knowledge-level justification, while
subtracting from knowledge any combination of truth, belief,
or being ungettiered makes no difference to whether p is
warranted enough to justify you in !-ing, for any !.
Therefore
(S3) If P is knowledge-level justified, then p is warranted
enough to justify you in !-ing, for any !.
The crucial premise in the subtraction argument is (S2). F&M
argue for it by considering a case where you are freezing
12 I am not sure weather the right way to think of outright belief on this view is as a
defeasibledisposition. That is how Ross and Schroeder describe it. But couldnt your
having a disposition to treat P as true in your reasoning just amount to the followingcondition being defeasibily true: If P is relevant to your reasoning, you will treat P as
true? One such defeater would be massively asymmetrical stakes. So if P is relevant toyour reasoning and the stakes are massively asymmetrical, you may not treat P as true. I
confess that I am not competent enough about the metaphysics of dispositions to have aview about this.
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cold and see a barn close ahead on the right. There is
another barn much further ahead on the left. They note that
because you want to get out of the cold as soon as you can,
if you know there is a close barn on the right (and
presumably, there are no countervailing considerations),
then there is a barn on the rightis warranted enough to
justify you in heading toward the barn on the right (rather
than the distant barn on the left). This remains true even if
there is instead a barn replica on the left and so you are
gettiered and fail to know there is a barn on the right.
Similarly if there is no barn on the right but merely a facade,
you are still justified in heading toward the barn on the right.
Even if, despite your evidence, you fail to believe there is a
barn on the right, you remain justified in heading toward the
barn on the right.
These intuitive considerations are taken by F&M to
support (S2). By definition, if you know p, you have
knowledge-level justification for p. KJ says that if you know
p, then p is warranted enough to justify you in !-ing for any !.
The subtraction argument says that subtracting truth, belief
and being ungettiered, you remain warranted enough to
justify you in !-ing, for any !. Thus, knowledge-level
justification for p makes p sufficiently warranted to justify you
in !-ing for any !.
As I see it, the main problem with the subtraction
argument hinges on the notion of being ungettiered. What
is it to be ungettiered? The only way to define being
gettiered", without solving the Gettier problem, is this: You
are gettiered just in case you have justified true belief that
isn't knowledge. (Indeed the title of Gettier's paper is "Is
justified true belief knowledge?).
But this definition raises the question whether the
existence of high stakes can be a gettier condition? This
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would be ruled out only if it were impossible for the stakes to
be high enough to rule out knowledge, without ruling out
knowledge-level justification. Because the subtraction
argument attempts to derive the stakes-sensitivity of
knowledge-level justification from the stakes sensitivity of
knowledge, it would be question-begging to assume this at
the outset.
If you can be gettiered by high stakes, then in order to
subtract your being ungettiered, while holding fixed your
knowledge-level justification, we would have to assume that
the stakes are high enough to preclude knowledge, even
given your knowledge-level justification. But high stakes
undermine knowledge by blocking justification for acting.
Thus you will have knowledge-level justification for p, with
insufficient warrant for p to justify you in acting. So (S3) will
not follow.
Are there other ways of defining being gettiered" that
exclude high stakes? F&M, at different, places talk about
"Gettier luck" conditions as well as "truth-relevant"
conditions. Neither of these specifications is precise enough
to capture all the conditions discussed in the Gettier
literature, but no matter. The problem remains. The
subtraction process begins with stakes low enough for you to
know P and thus low enough for P to be sufficiently
warranted to justify you in !-ing. Now suppose we subtract,
in addition to truth and belief, all the additional truth-
relevant/no-luck conditions for knowledge. Presumably, low
(enough) stakes is not a truth-relevant/luck condition. (If it
were, the subtraction process would result in stakes high
enough to prevent P from being sufficiently warranted to
justify you in !-ing and (S3) would not follow). So after the
subtraction process, low (enough) stakes will remain. But
then all that follows is:
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(S3') If P is knowledge-level justified and the stakes are low
enough for knowing, then p is warranted enough to justify
you in !-ing, for any !.
(S3') is weaker than (S3). Just because knowledge-level
justification for p ensures that p is sufficiently warranted to
justify acting when the stakes are low enough for knowing, it
doesn't follow that knowledge-level justification ensures that
p is sufficiently warranted to justify acting when the stakes
are too high for knowing. Again, the argument assumes that
one cannot have knowledge level-justification for P when the
stakes are too high for knowing. In essence, the subtraction
argument overlooks the possibility that low enough stakes is
an independent condition for knowledge.
Stewart Cohen
University of Arizona