Galilean resonances: the role of experiment in Turing's construction of machine intelligence

In 1950, Alan Turing proposed his iconic imitation game, calling it a 'test', an 'experiment', and the 'the only really satisfactory support' for his view that machines can think. Following Turing's rhetoric, the 'Turing test' has been widely received as a kind of crucial experiment to determine machine intelligence. In later sources, however, Turing showed a milder attitude towards what he called his 'imitation tests'. In 1948, Turing referred to the persuasive power of 'the actual production of machines' rather than that of a controlled experiment. Observing this, I propose to distinguish the logical structure from the rhetoric of Turing's argument. I argue that Turing's proposal of a crucial experiment may have been a concession to meet the standards of his interlocutors more than his own, while his construction of machine intelligence rather reveals a method of successive idealizations and exploratory experiments. I will draw a parallel with Galileo's construction of idealized fall in a void and the historiographical controversies over the role of experiment in Galilean science. I suggest that Turing, like Galileo, relied on certain kinds of experiment, but also on rhetoric and propaganda to inspire further research that could lead to convincing scientific and technological progress.