Thursday, 22 December 2016

The Turing Test.

A follow on from my previous post...

The Turing Test is a test invented by the mathematician Alan Turing in a paper published in 1950 in Mind. He is approaching the question, "Can Machines Think?"

Here is an excerpt from this paper:

1. The Imitation Game
I propose to consider the question, "Can machines think?" This should begin with definitions of the meaning of the terms "machine" and "think." The definitions might be framed so as to reflect so far as possible the normal use of the words, but this attitude is dangerous, If the meaning of the words "machine" and "think" are to be found by examining how they are commonly used it is difficult to escape the conclusion that the meaning and the answer to the question, "Can machines think?" is to be sought in a statistical survey such as a Gallup poll. But this is absurd. Instead of attempting such a definition I shall replace the question by another, which is closely related to it and is expressed in relatively unambiguous words.

The new form of the problem can be described in terms of a game which we call the 'imitation game." It is played with three people, a man (A), a woman (B), and an interrogator (C) who may be of either sex. The interrogator stays in a room apart front the other two. The object of the game for the interrogator is to determine which of the other two is the man and which is the woman. He knows them by labels X and Y, and at the end of the game he says either "X is A and Y is B" or "X is B and Y is A." The interrogator is allowed to put questions to A and B thus:

C: Will X please tell me the length of his or her hair?

Now suppose X is actually A, then A must answer. It is A's object in the game to try and cause C to make the wrong identification. His answer might therefore be:

"My hair is shingled, and the longest strands are about nine inches long."

In order that tones of voice may not help the interrogator the answers should be written, or better still, typewritten. The ideal arrangement is to have a teleprinter communicating between the two rooms. Alternatively the question and answers can be repeated by an intermediary. The object of the game for the third player (B) is to help the interrogator. The best strategy for her is probably to give truthful answers. She can add such things as "I am the woman, don't listen to him!" to her answers, but it will avail nothing as the man can make similar remarks.

We now ask the question, "What will happen when a machine takes the part of A in this game?" Will the interrogator decide wrongly as often when the game is played like this as he does when the game is played between a man and a woman? These questions replace our original, "Can machines think?"

He replaces this question with another question, "Can a machine fool a human into thinking the machine is conscious?"

The real question which most of these fictional stories about AIs answer in the affirmative, is, "Can a machine be created which actually is conscious?"

In fact, it is very hard to prove consciousness. No one really knows what it is. The only person one can be completely certain is conscious is oneself, when one is conscious. Believing others are conscious is actually an act of faith, in a sense.

The philosopher Alvin Plantinga in his book God and Other Minds 1967 proposed that belief in God was analogous to belief in other minds, both being apparent from evidence and fundamentally rational beliefs, but that neither belief in God nor belief in other minds could be conclusively proven against a determined sceptic.

Since we do not really know what consciousness is, how can we ever create it in a machine?

In other words, the Turing Test can never prove consciousness (Turing never claimed it could) it can only prove that a machine can be created that can imitate consciousness.

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