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(Image found here: http://en.wikipedia.org/wiki/File:Salachinesa2.png )

Last week I talked about the Turing Test, which suggests that if a computer can carry on a conversation with a person (via some text-based chat program) and the person can’t tell whether they’re talking to another human or a machine, then the machine may be considered intelligent.

One of the main objections to the Turing Test is the so-called Chinese Room argument. The Chinese Room is a thought experiment invented by John Searle to show that, even if a digital computer could pass the Turing Test, it still would not understand its own words, and thus should not be considered intelligent.

The argument goes like this. A digital computer (by which I just mean any ordinary computer, like your PC) can do several things. It can receive input; it can follow a long list of instructions (the program code) that tell it what to do with its input; it can read and write to internal memory; and it can send output based on these internal computations. Any digital computer that passes the Turing Test will simply be doing these basic things in a particularly complicated way.

So, the argument continues, let’s imagine replacing the computer with a man in a room. The computer’s goal is to pass the Turing Test in Chinese. Someone outside passes in slips of paper with Chinese characters, and the man must pass back slips of paper with responses in Chinese. But the man himself knows no Chinese, only English. However, the room contains an enormous library of books, full of instructions on how to handle any Chinese characters. For any message he receives, he looks up the characters in his library and follows the instructions (in English) on how to compose a response. He also has a pencil and paper he can use to write notes, do figuring as necessary, and erase notes, as instructed by his books. Once he has his answer, he writes it down and passes it back.

Here, the library of books corresponds to the computer’s program code, the pencil and paper corresponds to internal memory, and the person (who understands English but not Chinese) corresponds to the hardware that executes the program (which understands program instruction codes but not human language).

Searle points out that, although the man in the Chinese Room can theoretically carry on a perfectly good conversation in Chinese, there is nothing in the room (neither the man nor the books) that can be said to understand Chinese. Therefore, the Chinese Room as a whole can act as if it understands Chinese, but it doesn’t really. In the same way, a digital computer can act as if it’s thinking, but it isn’t really. The computer is only manipulating symbols, which have no meaning to the computer; it can never understand what it is doing. Real understanding requires an entirely different kind of hardware – like the kind in the human brain, made up of biological neurons – which a digital computer simply does not possess.

In fact, says Searle, even if a digital computer were to precisely simulate a human brain, neuron by neuron, and function correctly in just the same way, it still would not understand what it was doing in the way that a human brain does. This follows, he says, merely as a special case of the general Chinese Room argument.

I have my own opinion on the Chinese Room argument, which I’ll give tomorrow. In the meantime, what do you think? Is his argument convincing?

I’ve talked a lot about artificial intelligence on this blog. But what does “artificial intelligence” really mean?

How do we know if a machine is thinking?

One answer comes from Alan Turing (1912-1954):

Turing, like others I could name, was a professional badass. Among his more notable accomplishments:

• Widely considered the father of computer science
• Instrumental in breaking Enigma, the Nazi secret code
• Creator of the Turing Machine, a simple mathematical model for a computer, which Google recently featured on their homepage

Unfortunately for Turing, he was gay – more specifically, gay in 1950s England – which, at the time, was a criminal offense. He was “treated” with female hormones to avoid going to prison. Two years later, when he died from cyanide poisoning, it was ruled a suicide.

But back to our question. Can machines think?

Turing argued that the question, while interesting, tends to get mired in murky philosophical discussion about the meaning of the word “think.” He suggested we consider an alternative question, one that’s easier to define and has measurable results.

Suppose you’re chatting with someone online, using an instant messenger like AIM or MS Communicator. How do you know if the other person is a human or a computer? Today, it’s easy. Although there are so-called “chatbots” that simulate a human chat partner, none of them is likely to fool you for long. But Turing suggested that if a computer program was so sophisticated that you couldn’t tell whether you were talking to a human or not, then that’s a pretty good sign you’re looking at intelligence. This chat experiment is called the Turing Test.

Of course you’d have to define some parameters for the experiment. Who’s doing the testing – an average Joe or a savvy AI expert? How long does the test last? Etc. But these are fairly minor details, in my opinion.

It’s important to note, as Turing himself did, that the Turing Test should be considered sufficient but not necessary to establish intelligence. That is, a machine that passes the Turing Test might be judged intelligent, but a machine that fails the test is not necessarily unintelligent. It might simply be intelligent in other ways that don’t involve acting like a human.

The Turing Test has come under a lot of criticism from a lot of different angles. One argument says that the Test is a distraction from “serious” AI research, which today is highly specialized into specific intelligence problems, and rarely involves chatting. I’d counter that on two levels. First, as I just mentioned, Turing never claimed the test was the only definition of intelligence, so it isn’t supposed to be all-encompassing. But second, I have the feeling that by hyperspecializing, the AI community has lost its way. Researchers, it seems, have largely given up (at least for now) on creating a general-purpose, human-level intelligence capable of passing the Turing Test. I think that’s a mistake.

Another, more philosophical criticism says that a machine might pass the Turing Test by acting like it’s thinking, but not really be thinking. Tomorrow I’ll talk about that argument in more depth.

In the meantime – what do you think about the Turing Test? If a computer could pass this test, would you consider it intelligent?