The Contributions of Alan Turing

On 15 July 2019, the Bank of England revealed to the public the new face on the newly designed £50 note: the celebrated computer pioneer and codebreaker Alan Turing. According to the Bank, his legacy continues to have an impact both on modern science and society. Thus his inclusion is an acknowledgment and celebration of his lasting accomplishments.

Considered by many as the father of theoretical computer science and artificial intelligence, as well as a war hero for breaking the Nazi German Enigma code during the Second World War and saving millions of lives in the process, Turing was also a mathematician, logician, philosopher, and theoretical biologist.

Note that he was a homosexual. In 1952, the British government convicted him for gross indecency due to his relationship with another man. He went on probation that involved hormonal therapy and castration. On 24 October 2013, after years of petitions from influential figures, he was given a posthumous royal pardon signed by Queen Elizabeth II.

The Achievements and Contributions of Alan Turing: What Was His Legacy?

Theoretical Foundation for the Modern Computer

While completing his Ph.D. at Princeton University in 1936, he wrote the paper “On Computable Numbers, With An Application To The Entscheidungsproblem.” The Proceedings of the London Mathematical Society published this paper in 1937.

The paper became the foundation of computer science. Turing presented a theoretical typewriter-like computing machine that could solve any problem using simple instructions encoded on a paper tape. For instance, one computing machine could solve puzzles while the other could calculate square roots.

He demonstrated further that it is possible to construct a universal machine that could simulate any computing machine with specialized problem-solving functionality and could be programmed to perform different functions. Thus, this conceptual universal machine has provided the foundation for the modern computer.

Breaking the Enigma Code During World War II

The most notable accomplishment of Alan Turing was his role in the Second World War in which he worked as a codebreaker at the British top-secret Government Code and Cipher School. The facility employed about 12000 people who worked in shifts round-the-clock to decipher electronic messages between German Nazi forces.

Germany specifically used an encryption device called the Enigma machine to protect its military communication across all branches of its force. The polished had cracked the machine before World War II. However, the Nazi had made it more complicated with the introduction of more possible permutations.

Turing was able to design a counterpart machine called the Bombe that was capable of searching through the permutations. It essentially allowed the British to read all communications of the German naval force. The work of Turing and others at the Government Code and Cipher School shortened the war by two years, thus saving millions of lives.

Conceptual Artificial Intelligence and the Turing Test

Another legacy of Alan Turing is his work in the early ideas about artificial intelligence. In 1950, he published the seminal paper “Computing Machinery and Intelligence” via the quarterly peer-reviewed journal Mind. The paper discussed his notion that computers would become so powerful that they would be able to think.

The paper also introduced the Turing Test. It was designed to determine if a computer is capable of exhibiting intelligent behavior that is similar to or indistinguishable from human intelligence. The test specifically involves a human evaluator judging the natural language conversations between a human and a machine.

Nevertheless, the paper provided a futuristic vision for artificial intelligence. Although several ideas presented by Turing remained unrealized, a lot has changed since the 1950s. The different goals and fields of artificial intelligence, including machine learning and facial recognition, have permeated in day-to-day social and commercial transactions.

The Chemical Basis of Morphogenesis

Turing redirected his interest in mathematical and theoretical biology in 1951. The field involves the use of mathematical models and abstractions of the living organisms to analyze and understand the principles that govern the structure, functions, and behaviors of systems and other organic structures.

In 1952, he published the article “The Chemical Basis of Morphogenesis” that described how natural patterns such as spirals and stripes might emerge naturally out of a homogenous and uniform state. The paper introduced the reaction-diffusion theory of morphogenesis that has now served as a basic model in theoretical biology.

The paper specifically suggested that a system of chemicals reacting with each other and diffusing across space could explain the main phenomena behind morphogenesis. Other researchers have used the system to describe the morphogenesis in some species such as the spots and stripes in cats and the branching patterns of human lungs.


  • Turing, A. M. 1952. “The Chemical Basis of Morphogenesis.” Philosophical Transactions of the Royal Society of London B. 237(641): 37-72. DOI: 10.1098/rstb.1952.0012
  • Turing, A. M. 1950. “Computing Machinery and Intelligence.” Mind. 59(236): 433-460. DOI: 10.1093/mind/LIX.236.433
  • Turing, A. M. 1937. “On Computable Numbers, With An Application to the Entscheidungsproblem.” Proceedings of the London Mathematical Society. 2(42): 230-265. DOI: 10.1112/plms/s2-42.1.230