304 | 28 TURING’S CONCEPT Of INTEllIGENCE
Appearance matters
Turing described three versions of the imitation game. In addition to the famous version in
his 1950 ‘Computing machinery and intelligence’ article in Mind, he described a version of
the game in the 1948 ‘Intelligent machinery’ report for the National Physical Laboratory, and
a third in the 1952 discussion with Newman and others entitled ‘Can automatic calculating
machines be said to think?’. In these 1948 and 1952 works Turing said this about the concept
of intelligence:^14
[T]he idea of ‘intelligence’ is itself emotional rather than mathematical.
The extent to which we regard something as behaving in an intelligent manner is determined as
much by our own state of mind and training as by the properties of the object under considera-
tion. If we are able to explain and predict its behaviour, or if there seems to be little underlying
plan, we have little temptation to imagine intelligence. With the same object, therefore, it is pos-
sible that one man would consider it as intelligent and another would not; the second man would
have found out the rules of its behaviour.
As soon as one can see the cause and effect working themselves out in the brain, one regards it
as not being thinking but a sort of unimaginative donkey-work. From this point of view one might
be tempted to define thinking as consisting of ‘those mental processes that we don’t under-
stand’. If this is right then to make a thinking machine is to make one which does interesting things
without our really understanding quite how it is done.
The thesis set out in these remarks is that whether or not an entity is intelligent (or thinks)
is determined in part by how we respond to the entity. Does the entity appear intelligent? In
the case of intelligence in machines, this is at least as important as the machine’s processing
speed, storage capacity, or complexity of programming. The latter are examples solely of the
machine’s behaviour—in Turing’s words, the ‘properties of the object’ rather than the proper-
ties assigned by ‘our state of mind’. Turing’s approach to the concept of intelligence is a familiar
and philosophically well-developed approach to other concepts. For example, when we judge
that an object is yellow or beautiful, this is at least in part because it looks yellow or beautiful. So
too for morality, several philosophers have argued: what makes an action morally right, rather
than merely having beneficial consequences, is at least in part the fact that we feel obliged to
perform the action (or that we have some other affective response, such as desiring to perform
the action). Theories of this kind are called ‘response-dependence’ theories, and the concepts
concerned ‘response-dependent’ concepts. Turing’s 1948 and 1952 remarks on intelligence
explicitly set out a response-dependence theory of the concept of intelligence. An ‘emotional
concept’ is a response-dependent concept.
This approach to intelligence is also implicit in Turing’s imitation game. His paragraph
(quoted above) beginning ‘The extent to which we regard something as behaving in an intel-
ligent manner . . .’ immediately precedes his description of the 1948 game, which is restricted to
chess-playing. Turing continued:^15
It is possible to do a little experiment on these lines, even at the present state of knowledge. It
is not difficult to devise a paper machine which will play a not very bad game of chess. Now get
three men as subjects for the experiment A, B, C. A and C are to be rather poor chess players,