 When we look at the initial formulation that Turing provides of his test, it is clear that he thought that the passing of the test would provide probabilistic support for the hypothesis of intelligence. There are at least two different points to make here. First, the prediction that Turing makes is itself probabilistic: Turing predicts that, in about fifty years from the time of his writing, it will be possible to programme digital computers to make them play the imitation game so well that an average interrogator will have no more than a seventy per cent chance of making the right identification after five minutes of questioning. Second, the probabilistic nature of Turing’s prediction provides good reason to think that the test that Turing proposes is itself of a probabilistic nature: a given level of success in the imitation game produces—or, at any rate, should produce—a specifiable level of increase in confidence that the participant in question is intelligent (has thoughts, is possessed of a mind). Since Turing doesn’t tell us how he supposes that levels of success in the imitation game correlate with increases in confidence that the participant in question is intelligent, there is a sense in which The Turing Test is greatly underspecified. Relevant variables clearly include: the length of the period of time over which the questioning in the game takes place (or, at any rate, the “amount” of questioning that takes place); the skills and expertise of the interrogator (this bears, for example, on the “depth” and “difficulty” of the questioning that takes place); the skills and expertise of the third player in the game; and the number of independent sessions of the game that are run (particularly when the other participants in the game differ from one run to the next). Clearly, a machine that is very successful in many different runs of the game that last for quite extended periods of time and that involve highly skilled participants in the other roles has a much stronger claim to intelligence than a machine that has been successful in a single, short run of the game with highly inexpert participants. That a machine has succeeded in one short run of the game against inexpert opponents might provide some reason for increase in confidence that the machine in question is intelligent: but it is clear that results on subsequent runs of the game could quickly overturn this initial increase in confidence. That a machine has done much better than chance over many long runs of the imitation game against a variety of skilled participants surely provides much stronger evidence that the machine is intelligent. (Given enough evidence of this kind, it seems that one could be quite confident indeed that the machine is intelligent, while still—of course—recognizing that one’s judgment could be overturned by further evidence, such as a series of short runs in which it does much worse than chance against participants who use the same strategy over and over to expose the machine as a machine.)