John Searle |
The Turing Century blog has started a debate about the Turing Test for machine intelligence vs. John Searle's Chinese Room thought experiment. Searle claims that his elegant thought experiment shows that computers can never think no matter how smart they appear as they are just manipulating symbols, which after all is all that a Turing machine does. My take on this is as follow, but first I'll explain the Chinese Room in case you're not familiar with it. (Note: this is an exert from the final chapter of my book The Universal Machine)
Imagine you are
sitting in front of room with a locked door. You are a native Chinese speaker
and you’re able to ask questions of the room by writing them down in Chinese
characters on pieces of paper, which you post through a slot in the door. The
room replies in Chinese by sending its written replies back through the slot.
You spend time asking the Chinese Room factual questions and then progress to
asking its opinions on the economy, politics the arts and you even ask it to
tell you some jokes. All of its answers are perfect, just what you’d expect
from an intelligent Chinese person. It has passed the Turing Test with flying
colors – therefore it must be intelligent.
Then Searle unlocks
the door and shows you inside the Chinese Room. Inside waiting to receive
questions is an Englishman who doesn’t speak or read Chinese. He takes each
received question and identifies the Chinese characters from a big ledger and
writes down their corresponding numbers. He then, in a complex and laborious
process, cross-references the numbers with other ledgers and indices and eventually
obtains more numbers from which he obtains new Chinese characters that make up
his answer. He writes these characters down and posts them back through the
door.
Does the operator
understand Chinese? The answer is obviously no. He’s just following a laborious
mechanical process, a program. In fact he needn’t even know the characters make
up a language called Chinese. Does the operator understand the questions? Again
the answer must be no; he doesn’t even know they are questions because he
doesn’t understand Chinese. Therefore the Chinese Room is not intelligent and
never can be. It is, as Jefferson [a professor who clashed with Turing over machine intelligence] observed, just moving symbols around; there
is no understanding.
AI experts, including
myself, have struggled with Searle’s simple thought experiment. It does seem to
show that a universal machine by manipulating symbols can never be said to think. My take on this problem is to
consider the example of flight. Do birds fly? Of course they do, not all birds,
but most do and some do very well. Do planes fly? Yes they do, but they fly in
a very different way to birds. Planes don’t have feathers and they don’t flap
their wings, but they can fly great distances and carry much more weight than even
the largest bird. Therefore, flight is something that birds and planes both do but
by using different methods. Birds are living animals that have evolved to fly
and planes are engineered artifacts; machines that we have designed to fly.
Computers, like [IBM's] Watson, are machines that we have engineered to think. Watson isn’t made of
flesh and bone and it doesn’t have a brain, but it appears to think, just not
in the same way that we do. For some reason when it comes to intelligence and consciousness
we are much more sensitive about the abilities of our creations. If we engineer
a machine that performs as well as birds we proudly claim it flies but if we
engineer a machine that performs as well as or better than people in a game
show we doubt it’s thinking. I believe in the future the question of “do computers think?” will be one that
most people will not even consider. We’ll just all take it for granted that
computers act as if they are thinking and that’s good enough. Philosophers will
still be arguing about this in the future and the religious will always believe
that machines don’t have souls.
Nice post Ian! The Chinese room argument is a very thought provoking experiment. A couple of years ago I wrote my opinion of it here: http://santiontanon.blogspot.com/2009/03/chinese-room.html
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