I kind of agree but I think the point is what people mean by words is vague, so he said:

>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.

which is can you tell the AI answers from the humans ones in a test. It then becomes an experimental result rather than what you mean by 'think' or maybe by 'extrinsic difference'.