Alan Turing (1912-1954), the British mathematician, is known as the father of computer science. His 1936 paper “On Computable Numbers” described the Turing machine, a precise model of what any computer can and cannot calculate. He is not the same person as the father of the computer, a title that goes to Charles Babbage for designing the first programmable mechanical computer in 1837.
Why is Alan Turing called the father of computer science?
Computer science is, at its core, the study of what can be computed and how. Turing was the first to answer “what can be computed?” with a precise definition. Before 1936, “an algorithm” was an informal idea. After Turing, it was a mathematical object you could prove things about. Three pieces of his work built the field:
- The Turing machine (1936): a model of computation that is still taught in every B.Tech CSE theory of computation course.
- The universal machine (1936): one machine that can run any other machine’s instructions. This is the idea behind the stored-program computer, the design of almost every computer built since.
- The limits of computation (1936): his proof that some problems, such as the halting problem, can never be solved by any algorithm.
He then added work on practical computer design (1945-46) and on artificial intelligence (1950), which is why his name covers so much of the subject.
Alan Turing at a glance
| Item | Detail |
|---|---|
| Full name | Alan Mathison Turing |
| Born | 23 June 1912, Maida Vale, London |
| Died | 7 June 1954, Wilmslow, Cheshire (aged 41) |
| Education | King’s College, Cambridge (mathematics); PhD, Princeton University (1938) |
| Known for | Turing machine, halting problem, Enigma codebreaking, ACE computer design, Turing test |
| Honours in his name | ACM A.M. Turing Award (since 1966), Bank of England £50 note (from 2021) |
Alan Turing’s main contributions
1. The Turing machine
A Turing machine is an imaginary device with three parts: an unlimited tape divided into cells, a head that reads and writes one symbol at a time and moves left or right, and a finite table of rules that says, for each state and symbol, what to write, where to move and which state to enter next. Despite being that simple, it can carry out any calculation a modern computer can, given enough time and tape. The Turing machines and decidability guide works through examples.
2. Computability and the halting problem
In the same 1936 paper Turing showed there is no general method that can look at any program plus its input and decide whether it will eventually stop. This answered the Entscheidungsproblem (“decision problem”) posed by David Hilbert, in the negative. Alonzo Church reached the same answer independently with a different method (the lambda calculus), and the shared idea is now called the Church-Turing thesis: anything that can be computed by an algorithm can be computed by a Turing machine.
3. Codebreaking at Bletchley Park
During the Second World War Turing worked at Bletchley Park, Britain’s codebreaking centre. Building on earlier work by Polish cryptologists, he designed the Bombe, an electromechanical machine that searched for the daily settings of the German Enigma cipher. He also led the team (Hut 8) that broke German naval Enigma, which was vital for protecting Atlantic convoys.
4. The ACE computer
In 1945-46, at the National Physical Laboratory, Turing wrote a detailed design for the Automatic Computing Engine (ACE), one of the first complete designs for a stored-program electronic computer. A smaller version, the Pilot ACE, ran in 1950. He later worked on programming the Manchester computers.
5. Artificial intelligence and the Turing test
His 1950 paper “Computing Machinery and Intelligence” asked “Can machines think?” and proposed the imitation game, now called the Turing test: if a judge chatting by text cannot reliably tell a machine from a human, the machine is said to show intelligent behaviour. The question is still debated in the age of large language models.
6. Mathematical biology
In 1952 he published “The Chemical Basis of Morphogenesis”, explaining how patterns such as stripes and spots can arise from chemicals reacting and spreading. These are still called Turing patterns.
Father of computer science vs father of the computer
These two titles are easy to mix up in quizzes. They go to different people for different reasons:
| Title | Person | Reason |
|---|---|---|
| Father of computer science | Alan Turing | Turing machine and theory of computation (1936) |
| Father of the computer | Charles Babbage | Difference Engine (1820s) and Analytical Engine (1837), the first design for a programmable mechanical computer |
| First computer programmer | Ada Lovelace | Her 1843 notes on the Analytical Engine include an algorithm to compute Bernoulli numbers |
| Father of modern computer architecture | John von Neumann | 1945 EDVAC report describing the stored-program layout (CPU, memory, input/output) |
| Father of information theory | Claude Shannon | 1937 thesis linking Boolean algebra to switching circuits; 1948 theory of information |
| Father of artificial intelligence | John McCarthy (with Turing often credited too) | Coined “artificial intelligence” for the 1956 Dartmouth workshop |
| Father of the Indian supercomputer | Vijay Bhatkar | Led C-DAC’s PARAM 8000 (1991) |
For what the word “computer” itself means, see the full form of computer.
His later life and recognition
In 1952 Turing was prosecuted for homosexuality, then a crime in Britain, and accepted chemical castration instead of prison. He died of cyanide poisoning in 1954; the inquest ruled suicide. The British government apologised in 2009 and he received a royal pardon in 2013. The highest honour in computing, the ACM Turing Award, has carried his name since 1966, and his portrait has been on the Bank of England £50 note since June 2021.
FAQs
Who is the father of computer science?
Alan Turing, the British mathematician who defined computation with the Turing machine in 1936.
Who is the father of the computer?
Charles Babbage, who designed the Analytical Engine in 1837, a programmable mechanical computer that was never finished in his lifetime.
What is a Turing machine in simple words?
A thought-experiment computer with a long tape, a head that reads and writes one symbol at a time, and a rule table. It can compute anything a real computer can.
What is the Turing test?
A test proposed by Turing in 1950: if a human judge chatting by text cannot tell a machine from a person, the machine is said to behave intelligently.
Why is the Turing Award named after Alan Turing?
The ACM named its top prize after him in 1966 because his work on computability and computer design founded the field.