Who was Alan Turing and why should you care

by Captain Walker

Categories: Humanities

This post will not give a full biography of Alan Turing (23 June 1912 – 7 June 1954). For more on Turing head to Wikipedia. I will be summarising what’s important to me.

For a full biography read the book Alan Turing: The Enigma or the YouTube vid below (27 min). The Imitation Game – the movie is highly recommended.


Alan Turing, a name synonymous with the foundations of computer science and artificial intelligence, remains an iconic figure in both scientific and cultural spheres. Born on June 23, 1912, in London, Turing displayed an exceptional aptitude for mathematics and logic from a young age. His work at King’s College, Cambridge, led to the development of the Turing machine concept, a cornerstone of computational theory and the precursor to modern computing. Turing’s most notable contributions emerged during World War II, where his pioneering work in cryptanalysis, particularly in breaking the German Enigma code, was instrumental in the Allied war effort. Despite his monumental scientific achievements, Turing faced personal challenges and legal prosecution for his homosexuality, a reflection of the societal norms of his time. His untimely death in 1954 left a legacy that extends beyond his scientific genius, symbolising a pivotal moment in the struggle for LGBTQ+ rights. Today, Turing is celebrated not only as a father of computer science but also as a symbol of resilience and the ongoing pursuit of justice and equality. Turing IQ was estimated to be of 185 (0.01% of the population). Turing’s personal life was marked by tragedy. He was prosecuted for homosexual acts in 1952, which were criminal offences in the UK at the time. He was chemically castrated and died in 1954 from cyanide poisoning, which was ruled a suicide. Turing’s death and the preceding criminal conviction have been widely condemned. In 2009, the British government formally apologized for the treatment Turing received, and in 2013, he was posthumously pardoned by Queen Elizabeth II.

Early Life and Education of Alan Turing

Childhood and Family Background:

  • Birth and Family: Alan Turing was born on June 23, 1912, in Maida Vale, London, to Julius Mathison Turing, a member of the Indian Civil Service, and Ethel Sara Turing, daughter of a railway engineer. Turing’s family background was one of scientific and mathematical inclination.
  • Early Indications of Genius: Turing showed signs of high intelligence at a very young age, with a specific talent in mathematics and science. His abilities were evident despite some educational challenges, such as his struggles with traditional schooling methods.


  • Sherborne School: Turing’s formal education began at Sherborne School, a prestigious independent school in Dorset. He joined in 1926, where he initially struggled due to the school’s emphasis on classical studies over science and mathematics.
  • Academic Pursuits: Despite these challenges, Turing continued to focus on mathematics, teaching himself advanced topics. His natural aptitude for the subject became increasingly apparent, and he was eventually recognised for his talents by his teachers.

Higher Education:

  • King’s College, Cambridge: Turing enrolled at King’s College, Cambridge, in 1931. Here, he studied mathematics and was awarded a first-class honours degree in 1934. His academic prowess was remarkable, and he was elected a fellow of King’s College in 1935, at the age of just 22.
  • The Princeton Years: Turing furthered his studies at Princeton University in the United States from 1936 to 1938. Under the supervision of American mathematician Alonzo Church, Turing’s work at Princeton was integral to his development. He earned his Ph.D. with a dissertation on the central limit theorem in probability theory.

Early Academic Achievements:

  • Ground-breaking Work in Computability: Turing’s time at Cambridge and Princeton was crucial in shaping his future contributions. It was during this period that he developed the concept of the Turing machine, which became a foundational model for the theory of computation and algorithms.

Influence of Early Education on Later Work:

  • Formation of Theoretical Foundations: Turing’s early education, particularly his self-driven study of advanced mathematical concepts, laid the groundwork for his later revolutionary work in computation and artificial intelligence.
  • Development of Logical Thinking: The rigorous mathematical training he received, combined with his natural inclination towards problem-solving and logical analysis, played a critical role in his contributions to codebreaking during World War II and his subsequent pioneering work in computer science.

Contribution to Computability Theory:

The Turing Machine Concept:

  • Foundation of Modern Computing: In 1936, Alan Turing introduced the concept of the Turing machine in his paper “On Computable Numbers, with an Application to the Entscheidungsproblem.” This theoretical construct is a fundamental model of computation that can simulate any algorithm’s logic. It is the basis for understanding the limits of what can be computed and the design of modern computers.
  • Universal Machine: Turing’s idea of a “universal machine” that could take a program as input and execute it was ground-breaking. This concept laid the groundwork for the modern programmable computer.

The Entscheidungsproblem and Computability:

  • Addressing Hilbert’s Problem: Turing’s work was in response to David Hilbert’s Entscheidungsproblem, which asked whether a general algorithm could exist to determine the truth or falsity of any mathematical statement. Turing showed that no such universal algorithm could exist, a conclusion reached independently at around the same time by Alonzo Church, leading to the Church-Turing thesis.
  • Church-Turing Thesis: The Church-Turing thesis posits that any function that can be computed algorithmically can be computed by a Turing machine. This thesis is a fundamental principle in computer science and establishes a framework for understanding computational processes and their limitations.

Impact on Computer Science and Mathematics:

  • Foundation of Theoretical Computer Science: Turing’s work is the bedrock of theoretical computer science. It has influenced the development of complexity theory, algorithm design, and the understanding of artificial intelligence.
  • Informing Modern Algorithms: Turing’s theoretical framework informs the development of algorithms in all areas of computer science, from cryptography to machine learning.

Legacy and Recognition:

  • Enduring Influence: Turing’s contributions to computability theory continue to influence modern computing and the philosophical understanding of what it means to compute.
  • Turing Award: In his honour, the Turing Award, often referred to as the “Nobel Prize of Computing,” is awarded annually by the Association for Computing Machinery (ACM) to individuals for significant contributions to the field of computer science.

Relevance to Modern Technology:

  • Influence on Software Development: The principles laid out by Turing underpin much of modern software engineering and computational theory.
  • Role in Advancements in AI: Turing’s conceptual groundwork has been pivotal in advancements in artificial intelligence, particularly in understanding the theoretical limits and capabilities of AI systems.

In essence, Alan Turing’s contribution to computability theory not only resolved a significant mathematical problem of his time but also established the theoretical foundations for the field of computer science. His conceptualisation of the Turing machine and the universal machine model has profoundly impacted the development of modern computers and continues to be a critical reference point in the ongoing evolution of computational technology and artificial intelligence.

World War II and Cryptanalysis

Alan Turing’s work during World War II in the field of cryptanalysis was of monumental importance. His innovative methods in breaking the Enigma code not only had a direct and significant impact on the outcome of the war but also established foundational principles in the field of cryptography that resonate to this day. The secrecy surrounding his work during his lifetime has since given way to widespread recognition of his critical contributions to the Allied war effort and the broader field of computer science.

Role at Bletchley Park:

  • Recruitment and Codebreaking: During World War II, Alan Turing was recruited to join the Government Code and Cypher School at Bletchley Park, the British codebreaking centre. Here, he played a pivotal role in deciphering the coded messages of the Axis powers, particularly those encrypted with the German Enigma machine.
  • Team Leadership: Turing led a team at Hut 8, the section responsible for German naval cryptanalysis. He was instrumental in developing techniques for faster decryption of Enigma messages, which was crucial for the Allied war effort.

Development of Cryptanalytic Techniques:

  • The Bombe Machine: Turing’s most significant contribution was the development of the Bombe, an electromechanical machine designed to expedite the breaking of Enigma-encrypted messages. This device significantly enhanced the speed and efficiency of codebreaking operations at Bletchley Park.
  • Algorithmic Approach: Turing applied his mathematical and logical expertise to develop algorithms for codebreaking. His systematic approach transformed the art of cryptanalysis into a science, laying the groundwork for modern cryptographic techniques.

Impact on the War:

  • Shortening the War: The work done by Turing and his team at Bletchley Park is widely credited with shortening the duration of the war in Europe. By some estimates, their efforts may have shortened the war by as many as two to four years, saving countless lives.
  • Strategic Advantages: The intelligence gathered through Turing’s cryptanalysis, codenamed “Ultra,” provided the Allies with significant strategic advantages. It was instrumental in several key Allied victories, including the Battle of the Atlantic.

Secrecy and Post-War Recognition:

  • Highly Classified Work: The work at Bletchley Park remained a closely guarded secret for many years after the war, with its full significance only becoming widely known in the 1970s.
  • Posthumous Recognition: Turing’s contributions to the war effort and cryptanalysis were not fully acknowledged during his lifetime due to the classified nature of the work. However, he has been posthumously recognised as one of the most important figures in the Allied victory in World War II.

Legacy in Cryptography:

  • Foundational Work in Modern Cryptography: Turing’s work during World War II laid the foundation for modern cryptography. His approaches and methodologies continue to influence the field.
  • Inspiration for Future Cryptanalysts: Turing’s legacy in cryptanalysis extends beyond his wartime achievements, inspiring generations of cryptanalysts and security experts.

Personal Life and Legacy of Alan Turing

Alan Turing’s personal life, marked by brilliance and tragedy, and his posthumous recognition, highlight both the societal challenges he faced and the profound respect his scientific contributions command. His legacy extends beyond his monumental scientific achievements, embodying significant themes in the struggle for LGBTQ+ rights and ethical reflection within society.

Personal Life and Challenges:
  • Homosexuality in a Prejudiced Era: Alan Turing was homosexual, a fact that profoundly impacted his personal life and legacy. During his lifetime, homosexual acts were illegal in the United Kingdom, leading to significant personal challenges and legal issues.
  • Prosecution and Punishment: In 1952, Turing was prosecuted for homosexual acts under the then-existing laws. He was convicted and given the choice between imprisonment and probation conditioned on undergoing hormonal treatment, effectively chemical castration.
  • Tragic Death: Turing died on June 7, 1954, at the age of 41. His death was ruled a suicide by cyanide poisoning, although there have been discussions and debates over the circumstances surrounding his death.

Posthumous Recognition and Apologies:

  • Government Apology: In 2009, following a public petition, British Prime Minister Gordon Brown issued an official public apology on behalf of the British government for the way Turing was treated.
  • Royal Pardon: In 2013, Queen Elizabeth II granted Turing a posthumous royal pardon, recognising the injustice he had suffered under the British legal system because of his sexuality.

Legacy in Science and Culture:

  • Father of Computer Science: Turing is widely regarded as the father of theoretical computer science and artificial intelligence. His contributions to the development of computing, the concept of algorithms, and the theoretical underpinnings of AI have had a lasting impact.
  • Turing Award: The Turing Award, established in 1966 and often referred to as the “Nobel Prize of Computing,” is named in his honour. It is awarded annually by the Association for Computing Machinery (ACM) for contributions of lasting and major technical importance to the computing field.
  • Influence on LGBTQ+ Rights: Turing’s story has become a symbol of the struggle for LGBTQ+ rights and recognition. His posthumous pardon and the public acknowledgment of his mistreatment have been seen as significant steps in addressing historical injustices against the LGBTQ+ community.

Commemoration and Public Awareness:

  • Films and Literature: Turing’s life and work have been the subject of various films, plays, and books, most notably the film “The Imitation Game” (2014), which brought wider public awareness to his contributions and the injustices he faced.
  • Educational and Scientific Institutions: Various institutions, awards, and educational programs bear Turing’s name, reflecting his enduring impact on computer science, mathematics, and the broader scientific community.

Reflection in UK Ethical Values:

  • Shift in Societal Attitudes: The recognition and apology Turing received reflect a broader shift in societal attitudes in the UK towards LGBTQ+ rights and the acknowledgment of past injustices.
  • Influence on Law and Policy: Turing’s story has also influenced discussions and policies related to LGBTQ+ rights and historical injustices, contributing to a more inclusive understanding of ethical values in the UK.


In the annals of scientific history, few figures have sparked as much admiration and poignant reflection as Alan Turing. Born into a world on the cusp of technological revolution, Turing’s early life in London was marked by an innate brilliance in mathematics and logic. His academic journey, characterised by a profound engagement with mathematical concepts, led him to King’s College, Cambridge, and later to Princeton University. It was during these formative years that Turing laid the foundational stones of modern computing with the conception of the Turing machine—a theoretical model that would become the bedrock of computer science and artificial intelligence.

Turing’s genius found its most dramatic and consequential expression during the dark days of World War II. At Bletchley Park, amidst the secretive corridors of the British codebreaking centre, he emerged as a pivotal figure in the Allied war effort. His work in decrypting the German Enigma machine’s codes, leading to the creation of the Bombe machine, not only exemplified the heights of human intellect but also demonstrated the profound impact of abstract scientific thought on real-world events. The success of these endeavours, which significantly shortened the war and saved countless lives, remains one of the most luminous examples of the fusion of theoretical science and practical application.

However, the same society that Turing so significantly helped protect ultimately turned against him. In an era when homosexuality was not just stigmatized but criminalized, Turing found himself at odds with the legal and cultural norms of his time. His prosecution in 1952 for homosexual acts and the subsequent imposition of chemical castration marked a tragic turn in his life, culminating in his untimely death in 1954—a death that has been shrouded in mystery and speculation.

The legacy of Alan Turing is a tapestry of profound brilliance and deep injustice. His contributions to computer science laid the groundwork for the digital age, and his work in cryptanalysis remains a high watermark in the field. The Turing Award, often dubbed the “Nobel Prize of Computing,” stands as a testament to his enduring impact on the field he helped create. Yet, Turing’s life story also serves as a sombre reminder of the societal prejudices that can undermine even the most extraordinary of contributions.

In the years following his death, Turing’s legacy has been revisited and re-evaluated. The British government’s official apology in 2009 and the posthumous royal pardon in 2013 were not just acts of restitution for Turing but also symbolic acknowledgments of past societal failings. Today, Turing is celebrated not only for his scientific genius but also as an emblem of resilience against injustice and a beacon in the ongoing struggle for LGBTQ+ rights.

Alan Turing’s narrative is not just a chronicle of ground-breaking achievements in science and mathematics; it is a poignant story of a visionary mind that transcended the limitations of its time, a life that continues to inspire and evoke emotional reflection on the complex tapestry of human endeavour, ethics, and the enduring pursuit of justice and equality. His story remains a powerful testament to the indelible impact one individual can have on the world, both through the power of intellect and the legacy of personal struggle and triumph.

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