From LW's Blue Book:

The trouble which is expressed in this question is not really that we don’t yet know a machine which could do the job. The question is not analogous to that which someone might have asked a hundred years ago: ‘Can a machine liquify a gas?

Compare those two questions:

'Can a computer liquify gas?'

and

'Can a computer think?'


One has an answer. The other doesn't. That is Wittgenstein in a nutshell.

The first question is about the computer. The second question is about us and our use of the word 'think'. The second question doesn't have an answer because of the inherently limited nature of language.