“The idea behind digital computers may be explained by saying that these machines are intended to carry out any operations which could be done by a human computer. The human computer is supposed to be following fixed rules; he has no authority to deviate from them in any detail. We may suppose that these rules are supplied in a book, which is altered whenever he is put on to a new job. He has also an unlimited supply of paper on which he does his calculations.” (Turing 1950: 436).So a Turing machine is intended to do the work of a human being engaged in computation.
“The reader must accept it as a fact that digital computers can be constructed, and indeed have been constructed, according to the principles we have described, and that they can in fact mimic the actions of a human computer very closely.
The book of rules which we have described our human computer as using is of course a convenient fiction. Actual human computers really remember what they have got to do. If one wants to make a machine mimic the behaviour of the human computer in some complex operation one has to ask him how it is done, and then translate the answer into the form of an instruction table.” (Turing 1950: 438).
But a computer does not need to be conscious to do this, nor does it need to have any conscious perception, nor sensation, nor understanding of what it manipulates.
John Searle has therefore made a fundamental point on this issue: the computation of Turing machines, as these are designed, is purely syntactic—there is no semantics.
If a person manipulating symbols does not understand their meaning, as in Searle’s Chinese room argument, then no Turing machine can either if it only ever engages in automatic rule-governed symbol manipulation (Searle 1980: 82).
Searle, J. 1980. “Minds, Brains, and Programs,” Behavioral and Brain Sciences 3: 417–458.
Turing, Alan M. 1950. “Computing Machinery and Intelligence,” Mind 59.236: 433–460.