Full Idea
In about fifty years' time it will be possible to program computers to play the imitation game so well that an average interrogator will not have more than 70% chance of making the right identification after five minutes of questioning.
Gist of Idea
In 50 years computers will successfully imitate humans with a 70% success rate
Source
Alan Turing (Computing Machinery and Intelligence [1950], p.57), quoted by Robert Kirk - Mind and Body §5.9
Book Reference
Kirk,Robert: 'Mind and Body' [Acumen 2003], p.115
A Reaction
This is the famous prophecy called 'The Turing Test'. The current state (2004) seems to be that the figure of 70% is very near, but no one sees much prospect of advancing much further in the next 100 years. Dennett sees jokes as a big problem.