Denver, born 1932

John Searle

Shut a man who knows no Chinese in a room with a rulebook for answering Chinese questions, and to people outside he will seem fluent. He understands nothing. A computer running a program is in the same position, so programs alone cannot make minds.

The view

Searle taught at the University of California, Berkeley, for more than half a century, and made his name in the philosophy of language with a theory of speech acts. In 1980 he published "Minds, Brains, and Programs" in Behavioral and Brain Sciences, with replies from more than two dozen critics. Its thought experiment, the Chinese room, became one of the most argued-over ideas in the field.

Searle's target was "strong AI": the claim that an appropriately programmed computer does not just simulate a mind but literally has one, with understanding and other mental states. His own view, which he called biological naturalism, is that consciousness is a real biological phenomenon, caused by brain processes and realised in the brain, as digestion is caused by and realised in the stomach. It is entirely natural and physical. But it depends on the brain's specific causal powers, not on the abstract program it might be said to run.

The argument

Syntax is not sufficient for semantics. After Searle, "Minds, Brains, and Programs" (1980)

Imagine yourself locked in a room. Cards with Chinese characters are pushed through a slot. You know no Chinese, but you have a huge rulebook, written in English, telling you which characters to send back for any characters that come in. The rules are so good that your answers are indistinguishable from a native speaker's. You pass the Turing test in Chinese, yet you understand not a word. You are doing just what a computer does: manipulating symbols according to their shapes. Symbol shapes (syntax), Searle concludes, are never enough for meaning (semantics).

The incoming card asks, in Chinese, "Do you speak Chinese?" The reply says "Yes, fluently." Look inside and you see a man matching squiggles to squiggles. Searle anticipated the obvious replies. To the systems reply, that the whole room understands even if the man doesn't, he answered: let the man memorise the rulebook and do it all in his head. Now he is the whole system, and he still understands nothing.

Where he meets Dennett

Less than either would have liked. Both were naturalists who rejected the soul and saw minds as products of biology, and both thought much philosophy of mind was confused. Searle's line that, where consciousness is concerned, the appearance is the reality, is quoted in Dennett's 2016 essay. It marks their disagreement precisely.

Where they part

Their exchanges in the 1990s, partly in the New York Review of Books, were among the sharpest in modern philosophy. Dennett defended the systems reply. Of course the man doesn't understand Chinese, he said; he is a small part of the system, as a neuron is a small part of you. The thought experiment works by distorting scale. A rulebook that could really hold a fluent conversation on any subject would be unimaginably vast and intricate, and once you picture it properly, the intuition that "nothing in there understands" loses its grip. Dennett called thought experiments like this "intuition pumps", and said this one pumps the wrong intuition by inviting us to imagine something far simpler than what it describes.

Underneath is the disagreement over appearance and reality. For Searle consciousness is a first-person datum that cannot be an illusion. For Dennett that claim is exactly what needs testing.

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Further reading

• John R. Searle, "Minds, Brains, and Programs", Behavioral and Brain Sciences 3 (1980).
• John R. Searle, The Mystery of Consciousness (New York Review Books, 1997), which reprints his exchange with Dennett.
• Daniel C. Dennett, Intuition Pumps and Other Tools for Thinking (Allen Lane, 2013), with his account of the Chinese room.
• The Chinese room argument, Stanford Encyclopedia of Philosophy.