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‘at least 100 years’ before a computer passed his test. Shah and Warwick’s mistaken claim that
Eugene Goostman passed the Turing test rests on their having conflated Turing’s 30% predic-
tion with a specification of what counts as passing the test. They simply ignored Turing’s own
careful specification, in terms of the man imitates woman game, of what would actually count
as passing the test.
It is interesting to see Turing’s prediction about the extent of progress by the turn of the cen-
tury coming true—and we can surely forgive him for being just a few years out. But, as Turing
thought, his test may not be cracked for many years yet.
misunderstanding the Turing test
Another important misunderstanding about what Turing said concerns definitions. He is
repeatedly described in the (now gigantic) literature about the Turing test as having intended
his test to form a definition of thinking.^41 However, the test does not provide a satisfactory def-
inition of thinking, and so this misunderstanding of Turing’s views lays him open to spurious
objections, along the lines of ‘Turing attempted to define thinking but his definition does not
work’. Turing did make it completely clear though that his intention was not to define thinking,
saying ‘I don’t really see that we need to agree on a definition at all’,^42 but his words were not
heeded. ‘I don’t want to give a definition of thinking’, he said, ‘but if I had to I should probably
be unable to say anything more about it than that it was a sort of buzzing that went on inside
my head’.^43
Someone who takes the Turing test to be intended as a definition of thinking will find it
easy to object to the definition, since an entity that thinks could fail the test. For example, a
thinking alien might fail simply because its responses are distinctively non-human. However,
since Turing did not intend his test as a definition, this objection misses the point. Like many
perfectly good tests, the Turing test is informative if the candidate passes but uninformative if
the candidate fails. If you fail an academic exam it might be because you didn’t know the mate-
rial, or because you had terrible flu on the day of the exam, or for some other reason—but if you
pass fair and square, then you have unquestionably demonstrated that you know the material.
Similarly, if a computer passes the Turing test then the computer arguably thinks, but if it fails
nothing can be concluded.
One currently influential criticism of the Turing test is based on this mistaken idea that
Turing intended his test as a definition of thinking. The criticism is this: a gigantic database
storing every conceivable (finite) English conversation could, in principle, pass the Turing test
(assuming the test is held in English).^44 Whatever the judge says to the database, the database’s
operating system just searches for the appropriate stored conversation and regurgitates the
canned reply to what the judge has said. As the philosopher Ned Block has put it, this database
no more thinks than a jukebox does, yet in principle it would succeed in passing the Turing
test. Block agrees that this hypothetical database is in fact ‘too vast to exist’—it simply could
not be built and operated in the real world, since the total number of possible conversations is
astronomical—but he maintains that, nevertheless, this hypothetical counter-example proves
the Turing test to be faulty.^45
It is true that the database example would be a problem if the Turing test were supposed to
be a definition of thinking, since the definition would entail that this monster database thinks,
when obviously it does not. But the test is not supposed to be a definition, and the database