21 June 2012 Last updated at 00:00 By Prof Noel Sharkey Artificial Intelligence, University of Sheffield

Computer pioneer and artificial intelligence (AI) theorist Alan Turing would have been 100 years old this Saturday. To mark the anniversary the BBC has commissioned a series of essays. In this, the fourth article, his influence on AI research and the resulting controversy are explored.

Alan Turing was clearly a man ahead of his time. In 1950, at the dawn of computing, he was already grappling with the question: “Can machines think?”

This was at a time when the first general purpose computers had only just been built.

The term artificial intelligence had not even been coined. John McCarthy would come up with the term in 1956, two years after Alan Turing’s untimely death.

Yet his ideas proved both to have a profound influence over the new field of AI, and to cause a schism amongst its practitioners.

One of Turing’s lasting legacies to AI, and not necessarily a good one, is his approach to the problem of thinking machines.

He wrote: “I have no very convincing arguments of a positive nature to support my views.”

Instead, he turned the tables on those who might be sceptical about the idea of machines thinking, unleashing his formidable intellect on a range of possible objections, from religion to consciousness.

With so little known about where computing was heading at this time, the approach made sense. He asserted correctly that “conjectures are of great importance since they suggest useful lines of research”.

The rest is here: