John Searle: “Can Computers Think?”
Links:
Dictionary of Philosophy of Mind
The Internet Encyclopedia of Philosophy
Summary:
Searle is arguing against strong AI, the view that “the brain is just a digital computer and the mind is just a computer program”
Example of someone who holds this view: John McCarthy (coiner of “artificial intelligence”) who says that his thermostat has three beliefs (“It’s too hot in here”, “It’s too cold in here” and “It’s just right in here”)
It is essential to our conception of a digital computer that its operations can be specified purely formally; that is, we specify the steps in the operation of the computer in terms of abstract symbols – sequences of zeroes and ones… [which] are just numerals; they don’t even stand for numbers. [278.2]
That is, the operations of a computer are purely syntactical: they just manipulate symbols.
Our internal mental states, by definition, have certain sorts of
contents. If I am thinking about
Difference between syntax and semantics is like the difference between grammatical and meaningful. Grammar is concerned with syntax. The sentence “Colourless green ideas sleep furiously” is perfectly grammatical. However, we know that it is lacking in meaning, which is the paradigm of a semantic property. (“Content” of sentences and mental states can be specified in terms of the propositions they are about.)
The Chinese Room
A person inside a room gets input in the form of Chinese characters on cards, and produces output in the form of Chinese characters by looking up the input Chinese characters in a rule book (written in English) that shows him what Chinese characters to give back. It turns out that the input Chinese characters are meaningful questions and the output Chinese characters are appropriate answers to the questions, so to an outside observer, it looks as if whatever’s inside the room understands Chinese. But he doesn’t: he’s just following rules.
MORAL: computers are like the rule-follower. They don’t understand anything, even if they appear to do so.
The Argument in Axiom Form
1. Brains cause minds
2. Syntax is not sufficient for semantics
3. Computer programs are entirely defined by their syntactical structure
4. Minds
have mental contents (i.e., semantics)
Conclusion 1. No computer program by itself is sufficient to give a system a mind. Programs are not minds.
Conclusion 2. The way that brain functions cause minds cannot be solely in virtue of running a computer program
Conclusion 3. Anything else that caused minds would have to have causal powers at least equivalent to those of the brain
Conclusion 4. For any man-made object that had mental states equivalent to human mental states, the implementation of a computer program would not by itself be sufficient. Rather, the object would have to have powers equivalent to the human brain.
SUM:
mental states are biological phenomena. Consciousness, intentionality, subjectivity and mental causation are all a part of our biological life history, along with growth, reproduction, the secretion of bile, and digestion. [283.2]
Responses
1. The Systems Response: Yes, the man in
the Chinese Room does not understand Chinese, but the whole system of which he is a part, does.
Searle’s Reply: You can change the example so that the man has memorized the
rule book, in effect becoming the system.
He still doesn’t understand
Chinese.
2. The Robot Response: Put the room inside
a computer which can interact causally with its environment. That gives you the causal properties
necessary for semantics.
Searle’s Reply:
a) Even if I’m inside a robot, I still don’t understand Chinese
b) You’re giving up on Strong AI if you have to have extra features besides simple formal processes.
What is Searle’s Positive View?
Doesn’t appear to be the identity theory, because of his
Martian example (“green slime” [282.2]).
Can’t be functionalism, because that’s what the Chinese Room attacks
(along with Behaviourism). So is it dualism? He denies this, but his insistence on the
first person perspective sounds very Descartes-like.