Philosophers of mind use Turing machines in the same way pharmaceutical companies use mice: as a simpler stand-in for humans.
What Is a Turing Machine?
Think of a Turing machine as a long tape divided into squares. Each square can hold a symbol, such as a number or a letter.
The machine has a head that can read these symbols. It can also change them, erase them, or leave them as they are. The machine can move the tape left or right in order to work on different squares.
Now imagine that the machine has a set of rules, or a program, that tells it what to do depending on two things:
- The symbol it reads.
- The state it is in.
The state is like the machine’s current mood. It changes based on what the machine reads.
The program and the machine’s states guide its actions. They determine whether the machine changes a symbol, moves the tape, or switches to a different state.
Turing’s idea was to show that a machine following this kind of program can perform any calculation. Modern computers are, in this sense, scaled-up versions of a Turing machine.
How Can We Tell Whether a Machine Can Think Like a Human?
One answer is: the Turing Test.
Imagine that you are texting with someone, but you do not know whether they are a person or a computer.
In the test, you chat with this unseen “someone” through a computer. You ask questions, tell jokes, or talk about anything.
If you, or a group of people, cannot tell whether the responses are from a human or a computer, then the computer passes the test.
Questions
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Does a Turing machine that passes the Turing Test actually have human intelligence? What is intelligence? If the Turing Test does not prove that a machine has human intelligence, what would prove it?
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Does a machine that passes the Turing Test have consciousness? How would we know whether a machine has consciousness if not by using the Turing Test?
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Does the fact that a Turing machine passes the Turing Test imply any ethical facts? Do we have to treat the machine differently? Are we allowed to turn it off if it says something we do not like? Can we delete its memory or erase the program?
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If a Turing machine has human intelligence, then human intelligence must be similar to a very large computer program. Is human intelligence a big program? Would we ever be able to figure out what this program is?
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What would a society where machines have human intelligence be like? Would it make society better or worse? Would it affect how we interact with technology? Would it affect how we interact with each other?