The most famous challenge to the aims of computational cognitive science and artificial intelligence is the philosopher John Searle's 1980 'Chinese Room' argument. Searle argued that the fact that machines can be devised to pass the 'Turing Test', that is, respond to input with the same output that a mind would give, does not mean that mind and machine are doing the same thing: for such machines lack understanding of the symbols they process. Nineteen specially written essays by leading scientists and philosophers assess, renew, and respond to this crucial challenge—fascinating reading for anyone interested in minds and computers.