René Descartes
From: "Passions of the Soul" (1649)
Translator unknown
a resemblance to our body and imitated our actions as far
as it was morally possible to do so, we should always have two very certain
tests by which to recognise that, for all that, they were not real men. The
first is, that they could never use speech or other signs as we do when placing
our thoughts on record for the benefit of others. For we can easily understand
a machine's being constituted so that it can utter words, and even emit some
responses to action on it of a corporeal kind, which brings about a change in
its organs; for instance, if it is touched in a particular part it may ask what
we wish to say to it: if in another part it may exclaim that it is being hurt,
and so on. But it never happens that it arranges its speech in various ways, in
order to reply appropriately to everything; that may be said in its presence,
as even the lowest type of man can do. And the second difference is, that
although machines can perform certain things as well as or perhaps better than
any of us can do, they infallibly fall short in others, by the which means we
may discover that they did not act from knowledge, but only from the
disposition of their organs. For while reason is a universal instrument which
can serve for all contingencies, these organs have need of some special
adaptation for every particular action. From this it follows that it is morally
impossible that there should be sufficient diversity in any machine to allow it
to act in all the events of life in the same way as our reason causes us to
act.