Tuesday 28 April 2015

Buridan's ass

Buridan's ass thought he had the answer. Each time he could not decide between two bales of hay, he would toss a coin. If it came up heads, he would start with the bale on the right; if tails, he would start with the bale on the left.

But there would be an equally good rule, heads-left, tails-right. How could he decide between these two rules?

Then he had another idea. He would build an electronic device with a loudspeaker and a button. When he pushed the button, it would randomly say "Right" or "Left", and he would follow its instruction. It would not matter whether it was genuinely random, or determined but as near random as made no difference (for example, if it picked up whatever radio waves happened to be around and used them to decide when to stop a counter that was flipping left-right a million times a second). He did not have to worry about every philosophical problem.

But the device would not have any notion of the meanings of the words "right" and "left". It would be like the person handling the dictionaries inside Searle's Chinese room. So the ass would have to make an arbitrary choice between the rule that said the sound of the word "right" meant he was to choose the bale on the right, and the equally good rule that it meant he was to choose the bale on the left.

He began to wonder whether there was any way to get rid of the arbitrariness, as opposed to just moving it to a different place. Perhaps there could not be. Perhaps for any rule or system of rules, there would have to be a mirror image rule or system that would always have the opposite effect. This might be an inevitable result of the symmetry of the situation that created the problem.

At this point he felt hungry. He went out into the yard, and was very pleased to see that there was only one bale of hay. And as it was directly in front of him, he would start by eating the middle part of it.

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