Alan Turing

Key ideas

In 1936 Turing described an abstract machine that reads and writes symbols on a tape following simple rules, and showed that such a machine can carry out any calculation that can be done by following a procedure. The Turing machine is still the standard definition of computation, and the idea behind every modern computer.

In his 1950 paper 'Computing Machinery and Intelligence', he replaced the question 'Can machines think?' with a test, the imitation game, now called the Turing test: if a judge in conversation cannot reliably tell a machine from a human, we have as much reason to call the machine intelligent as we have for other people. He then answered a series of objections, many of which are still made today. The paper is the starting point of machine consciousness and the Chinese room.

Life, briefly

Turing studied mathematics at King's College, Cambridge. During the Second World War he worked at Bletchley Park, where he played a leading part in breaking German naval codes. Afterwards he worked on early computers in London and Manchester, and on mathematical biology.

In 1952 he was prosecuted under British laws against homosexuality and accepted hormone treatment in place of prison. He died in 1954. The British government apologised in 2009, and he received a posthumous royal pardon in 2013.

Major works

• On Computable Numbers (1936)
• Computing Machinery and Intelligence (1950)
• The Chemical Basis of Morphogenesis (1952)

Further reading

• EncyclopediaStanford Encyclopedia of Philosophy: Alan Turing
• WikipediaAlan Turing