 Other people have thought that the Turing Test is not sufficiently demanding: we already have anecdotal evidence that quite unintelligent programs (e.g., ELIZA—for details of which, see Weizenbaum (1966)) can seem to ordinary observers to be loci of intelligence for quite extended periods of time. Moreover, over a short period of time—such as the five minutes that Turing mentions in his prediction about how things will be in the year 2000—it might well be the case that almost all human observers could be taken in by cunningly designed but quite unintelligent programs. However, it is important to recall that, in order to pass Turing’s Test, it is not enough for the computer program to fool “ordinary observers” in circumstances other than those in which the test is supposed to take place. What the computer program has to be able to do is to survive interrogation by someone who knows that one of the other two participants in the conversation is a machine. Moreover, the computer program has to be able to survive such interrogation with a high degree of success over a repeated number of trials. (Turing says nothing about how many trials he would require. However, we can safely assume that, in order to get decent evidence that there is no more than a 70% chance that a machine will be correctly identified as a machine after five minutes of conversation, there will have to be a reasonably large number of trials.) If a computer program could do this quite demanding thing, then it does seem plausible to claim that we would have at least prima facie reason for thinking that we are in the presence of intelligence. (Perhaps it is worth emphasizing again that there might be all kinds of intelligent things—including intelligent machines—that would not pass this test. It is conceivable, for example, that there might be machines that, as a result of moral considerations, refused to lie or to engage in pretence. Since the human participant is supposed to do everything that he or she can to help the interrogator, the question “Are you a machine?” would quickly allow the interrogator to sort such (pathological?) truth-telling machines from humans.)