phl of mind paper

7/31/2019 Phl of Mind Paper

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David Krajewski

Philosophy of Mind

Topic- Discourse V & Turings Test

Do only human beings have the capacity to think? Descartes concludes in Discourse V

that the answer is yes and machines do not have this capacity. Turing, in contrast, concludes that

a machine (a digital computer) does have the capacity to think. I will first present Descartes

argument and the criteria he uses for his determination. Then, I will present the criteria that

Turing uses to draw his conclusion, which is commonly called The Turing Test. Finally, I will

discuss an objection that Turing considers against The Turing Test and show how it is relevant

to Descartes argument.

Central to Descartes argument is the differentiation between a brute and a human being.

The differentiation has to do with the disparity in eachs capacity to respond to the external

world. A brute is any animal that is considered non-human, like a cat or a bear and so on. It is

something that is entirely deterministic and limited due to its biological program. In other

words, is limited to a set of pre-programmed responses. For instance, a cat is pre-programmed to

respond in a certain way to certain stimuli. If it feels dirty, then it will begin to lick itself clean.

If it feels physically threatened, then it will attempt to defend itself with its sharp claws. Try to

conceive of a cat that does not do those kinds of things in response to those kinds of stimuli. It is

difficult to do so for the cat is severely limited due to its biological program. Now consider how

a human responds to various things in the world. If she feels physically threatened, then she may

defend herself or run away. And she may defend herself with a gun, or a knife or her own fists.

If she feels dirty, then she may take a shower, a bath, or simply wash her hands. Notice how, in

contrast to the cat, the human can respond to similar situations in numerous ways for it is not


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limited to the extent that the cat is limited. It is also possible for a human to respond absurdly to

any situation. If he feels physically threatened, he may jump out a window or run in front of a

car and choose not to defend himself. There are limitless possibilities for him whereas the cat

can only respond in ways that its pre-programmed responses dictate it can.

A human has limitless possibilities in so far as he can respond appropriately to any

given situation whereas a brute cannot. Descartes claims that it is conceivable to imagine a

machine that perfectly resembles a brute in all physical respects. In fact, it resembles a brute so

well that it is indistinguishable from the real brute. Descartes calls this machine an

automaton. Like a brute, he claims it is limited to pre-programmed responses. It cannot

respond in limitless ways like a human can. Suppose that a human were to meet this automaton.

Consider an automaton cat. The human would observe that the automaton cat would lick itself if

it were dirty or use its claws if it were threatened. The human would have no reason to believe

that the automaton is not a real cat for it mimics the real cat flawlessly. Suppose a real human

encountered an automaton human. The human begins to ask the automaton human basic

questions like What day is it? or How is the weather?. The automaton responds

appropriately. The human now asks the automaton more specific questions like What did you

do five minutes ago? or What do you think of the current economic crisis?. The automaton is

lost for words and cannot provide an appropriate response. It may be that whoever

programmed this automaton only programmed it to respond appropriately to very basic questions

and so it cannot respond to anything very specific. The real human, aware that human

automatons exist, concludes that it is an automaton and not an actual human.

The human can tell the difference between a real and automaton human whereas he

cannot tell the difference between the real and automaton cat. He cannot tell the difference


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between the latter for a real cat does the same things that the automaton cat was doing. However

in the former case, a real human would respond appropriately to the very basic questions as well

as the specific questions. Descartes points to the expression of language as making the

difference. I may formulate an answer to the question about the economic crisis, however

inaccurate my assessment is. The automaton, though, simply cannot formulate an answer to the

question for it is not capable of producing limitless language. It is irrelevant whether my answer

is right or wrong in this context for at least I can produce an appropriate answer. An automaton

cannot produce an appropriate answer at all and perhaps its attempt is a jumbled mess of words

that do not make sense. As real humans, our responses are not a jumbled mess of words for

our acquisition of sophisticated language allows us to formulate coherent sentence after coherent

sentence. There is nothing restricting us in forming these sentences (we are not held down by

a program) therefore we can theoretically converse forever.

Might it be conceivable for a programmer to make an automaton that is capable of

answering highly specific questions in detail? I think yes. Eventually though, if the

conversation with the automaton were carried on long enough, I suspect that Descartes would

assume it would stumble for it would fail to respond appropriately at some point or another. If I

as a real human were in an endless conversation, I could produce appropriate response after

appropriate response without ever faltering. Eventually all real humans die and so it is

practically impossible to forever respond appropriately. However, it is logically possible for a

human to respond appropriately for an infinite amount of time. For Descartes, the capacity to

respond appropriately for an infinite amount of time equates to thought. Therefore, a human

can think and machines and brutes cannot.


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Turing does not distinct between brutes and human beings. He instead presents The

Turing Test. The test involves a game that is to be played between two players and an

interrogator. Player A and the interrogator are human beings whereas Player B is a digital

computer. The objective of the game for the interrogator to successfully decide which player is

the human and which player is the machine after posing a series of questions to both players (he

knows that one player is the computer and one the machine going into the game). It is the

machines objective to fool the interrogator into getting the players mixed up. Turing supposes

that each player is unseen to the interrogator and the questions are entered in on a typewriter.

Suppose that the interrogator asks How hot is it in the room? or What move should I make in

chess under such and such circumstances?. Keep in mind that the computer is a sophisticated

machine and carefully programmed to respond appropriately to a great deal of questions. It does

so and the interrogator might think the answers are more detailed and articulate from Player B

(computer) than from Player A (human). He then might be lead to believe that the more detailed

and articulate answers came from a human. If after his questioning the interrogator decides that

Player A is the computer and Player B is the human being, then he has failed. If the interrogator

fails to discriminate between the human and computer player, then the computer passes The

Turing Test. Turing claims that if the computer passes his test then it should be concluded that

the computer has the capacity to think. For Turing, the computer does not have to respond

appropriately to an infinite amount of questions to have that capacity, unlike in the conclusion of

Descartes.

There is an objection that Turing considers that Descartes himself might pose. It is the

Lady Lovelace objection which claims that the computer cannot really do anything new; it can

only do what it is programmed to do. Descartes argument concludes that human beings can do


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new things in the sense that they can produce appropriate responses in any given situation. It

follows from the above objection that computers are constrained to their computer program.

Computers cannot produce anything new for what they can produce is already ingrained into

them and limited by their programmers. This constraint is analogous to what brutes and

automatons are constrained by, which is their biological program. Brutes and automatons are

only capable of producing what is ingrained in them by their biology and it is their lack of human

language that makes this so. Turing may concede that brutes and automatons have this

constraint; however he does not believe that computers share it.

Turing would agree that brutes and automatons are limited by their biology. He would

respond to Descartes (and the above objection) by assuming that the entire world is determined

by physical laws and its inhabitants are determined by physical as well as biological laws. It

would follow that brutes, automatons and even human beings are constrained by these laws.

Brutes as well as humans would be constrained by their biological programs. So, just as humans

are programmed by biology (through genetics) a computer is programmed by its human

programmers. If a human is biologically programmed just as a computer is technologically

programmed, can a human do anything new? The Lady Lovelace objection seems to be

committed to making that claim for it implies that being programmed in any sense is to be

limited in what one can do. Genetics determine in part, personality and all of ones physical

appearance. If my personality is a result of my genetics, then how can I really do something

new? How can I break apart from my genetic makeup? Again, it seems that the objector has to

say that I am completely constrained by my biology and therefore cannot do anything new.

The above consequence of the objection is certainly undesirable for Descartes. He would

not want to conclude that human beings cannot do anything new due to their biological program


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for it would be in direct contradiction to his argument. Instead, Descartes would point to how a

human uses language compared to how a computer uses language. Much like the human

automaton, the sophisticated computer can carry on a conversation with a human being. The

conservation might even go on for a substantial amount of time and the human would not realize

that she is talking to a machine (assuming the machine is behind a wall or unseen in some way).

The computer is very advanced and it can even carry on an intelligent philosophical debate.

However, just like the automaton, it would eventually run out of things to say. It would be

unable to formulate a coherent response to a question at some point for its program would have

pulled out all the stops. For Turing, this consequence is not important. We can imagine that

the computer in question would pass The Turing Test after a reasonable one hour conversation.

Merely passing The Turing Test would not satisfy Descartes. He would have to conclude that

the computer can go on forever in conversation or else he has to say that it does not have the

capacity to think. It turns out that it does not respond appropriately forever and so Descartes

concludes that the machine (however intelligent) cannot think.

Descartes has shown then that a computer cannot do anything new which was what the

Lady Lovelace objection was trying to establish. Turings reply shows that the objection leads

to an undesirable consequence. However, Descartes argument from Discourse V gets away

from that undesirable consequence by pointing to the differences in language present in the

machine and the human. Descartes might concede that biology limits human beings however it

does not limit them to the extent that it limits brutes and automatons. And, in response to

Turing, biology does not limit human beings to the extent that a computers program limits a

machine. A human can respond to an infinite set of questions whereas eventually the machine is

bound to fail.


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phl of mind paper

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