June 23 marks the 100th birthday of Alan Turing. If I had to name five people whose personal efforts led to the defeat of Nazi Germany, the English mathematician would surely be on my list. Turing's genius played a key role in helping the Allies win the Battle of the Atlantic—a naval blockade against the Third Reich that depended for success on the cracking and re-cracking of Germany's Enigma cipher. That single espionage victory gave the United States control of the Atlantic shipping lanes, eventually setting the stage for the 1944 invasion of Normandy.

But even before this history-changing achievement, Turing laid the groundwork for the world we live in today by positing a "universal computing machine" in 1936. "It is possible to invent a single machine which can be used to compute any computable sequence," he contended. His proposed device could read, write, remember, and erase symbols. It would produce the same results "independent of whether the instructions are executed by tennis balls or electrons," the historian George Dyson notes, "and whether the memory is stored in semiconductors or on paper tape."

Turing's essential idea, aptly summarized by his centenary biographer Andrew Hodges, was "one machine, for all possible tasks." The concept guided the generation of computer theorists and builders who flourished after the Second World War, among them Turing himself for a time.

Sadly, if the saying "no good deed goes unpunished" ever applied to anyone, it applied to Turing. In 1952, as the Cold War accelerated, the British government arrested him for violating the same indecency law that put the playwright Oscar Wilde in prison. The code-breaker made no apology for his homosexuality, but he accepted an alternative punishment of "chemical castration"—injections of estrogen "intended to neutralise his libido," as Hodges puts it. The attention of the case and the "cure" proved too much for him. In 1954, Turing was found dead of cyanide poisoning; a coroner concluded that he had committed suicide.

Alan Turing's achievements speak for themselves—but the way he lived his remarkable and tragically shortened life is less known. What follows are seven Turing Qualities that we could all emulate to our benefit.

1. Try to see things as they are

Alan Turing was born in 1912, the son of a civil servant in Madras, a state within British-controlled India. As Hodges observes in his book, Alan Turing: The Enigma, Alan's father John Mathison Turing was an assiduous student of Indian life. John Turing spent a decade learning everything he could about agriculture and public health across three rural districts, and even mastered the Telugu language. The boy's mother came from a line of railway and hydraulic engineers.

Young Alan appears to have picked up his parent's passions for learning, but he was farmed out to wards as his parents commuted back and forth from India. The result was a "naughty and willful" lad who often rebelled against his betters and showed a yearning for the literal and frank truth.

When Mrs. Turing had to leave for India in 1915, she had a little talk with her three-year old son. "You'll be a good boy, won't you?" she pleaded. "Yes," Alan replied, "but sometimes I shall forget!"

This sort of literal truth drove Alan's superiors to distraction. When his father returned to England, he gave his child a lecture about keeping his shoe-tongues in proper order. "They should be flat as a pancake," Mr. Turing proclaimed. Alan was unimpressed by this dictum. "Pancakes are generally rolled up!" he shot back.

From the beginning, Alan Turing was a dedicated fan of the actual properties of things. His nanny discovered this the hard way. "You couldn't camouflage anything from him," Hodges quotes her recalling. "I remember one day Alan and I playing together. I played so that he should win, but he spotted it. There was a commotion for a few minutes."

When Turing was about ten years old, someone gave him a copy of Edwin Tenney Brewster's popular book, Natural Wonders Every Child Should Know. It made a big impression on the boy.

"For, of course, the body is a machine," the tome explained, and went on:

It is a vastly complex machine, many, many times more complicated than any machine ever made with hands; but still after all a machine. It has been likened to a steam engine. But that was before we knew as much about the way it works as we know now. It really is a gas engine; like the engine of an automobile, a motor boat, or a flying machine.

In a sense, the rest of Alan Turing's life was about collecting small component facts and ideas about human and non-human machines, then putting them together in new and hugely original ways.

2. Don't get sidetracked by ideologies

Turing went to King's College, Cambridge in 1931. Two years later the Oxford Union debating society issued its famous declaration: "That this House will in no circumstances fight for its King and Country." While not an explicitly pacifist statement, the Oxford Pledge reflected enormous disillusionment with the course and consequences of the First World War.

1933 was a year for radical credos. The global Great Depression was in full swing. "Am thinking of going to Russia some time in vac[ation] but have not yet quite made up my mind," Alan wrote to his mother. He also joined an organization called the Anti-War Council. "Politically rather communist. Its programme is principally to organize strikes amongst munitions and chemical workers when government intends to go to war."

But none of this ever came to anything. Turing didn't go to the Soviet Union, and he found the Marxist institutions on campus just as suffocating as the public school that he attended. Turing "was not interested in organising anyone," Hodges observes, "and did not wish to be organised by anyone else. He had escaped from one totalitarian system, and had no yearning for another."

Not only did Alan Turing reject a Marxist framework, but he would soon fix his skeptical sights on an overarching question haunting theoretical mathematicians at the time:

"Could there exist, at least in principle, a definite method or process by which it could be decided whether any given mathematical assertion was provable?"

3. Be practical

This question was called the Entscheidungsproblem, or the "decision problem" in English. The influential mathematician David Hilbert posed this and two other questions at a major conference in 1928. All three are summarized by Hodges:

First, was mathematics complete in the technical sense that every statement (such as 'every integer is the sum of four squares') could either be proved, or disproved. Second, was mathematics consistent, in the sense that the statement '2 + 2 = 5' could never be arrived at by a sequence of valid steps of proof. And thirdly, was mathematics decidable? By this he meant, did there exist a definite method which could, in principle, be applied to any assertion, and which was guaranteed to produce a correct decision as to whether that assertion was true.

Hilbert thought that the answer to all three of these conundrums was yes. But a young mathematician named Kurt Gödel countered with several "incompleteness theorems" that pretty much knocked questions one and two out of the room. As his biographers Ernest Nagel and James B. Newman put it, Gödel showed that it was:

impossible to establish the internal logical consistency of a very large class of deductive systems - elementary arithmetic, for example - unless one adopts principles of reasoning so complex that their internal consistency is as open to doubt as that of the systems themselves . . . Second main conclusion is . . . Gödel showed that Principia, or any other system within which arithmetic can be developed, is essentially incomplete. In other words, given any consistent set of arithmetical axioms, there are true mathematical statements that cannot be derived from the set . . . Even if the axioms of arithmetic are augmented by an indefinite number of other true ones, there will always be further mathematical truths that are not formally derivable from the augmented set.

You could even come up with your own statement that proved its own unprovability, Gödel noted, such as "Formula G, for which the Gödel number is g, states that there is a formula with Gödel number g that is not provable within [Whitehead and Russell's Principia Mathematica] or any related system."

But then there was that thorny third question, the Entscheidungsproblem. One fine day in 1935, Turing lay in a meadow after a long distance run when the answer came to him—how to determine the existence or non-existence of such a "definite method." He envisioned a machine that functioned as a kind of super-typewriter with an unlimited supply of paper. It could produce symbols, of course, but it could also scan them and move to the left and right at will. Such a machine could resolve the dilemma.

In his famous essay "On Computable Numbers, with an Application to the Entscheidungsproblem," Turing took the reader through a mechanically constructed algorithmic process that demonstrated there existed no "definite method" for solving each and every mathematical question—the machine would produce "uncomputable" numbers that, by their nature, were unsolvable. As Turing biographer Jack Copeland observes, Turing's machine showed that the decimal representations of some real numbers were "so completely lacking in pattern" that no finite table of instructions it could read would be able to follow them.

Turing had done more than resolve a thorny philosophical/mathematical question, however. By tackling the Entscheidungsproblem in practical terms, he had outlined the framework for a universal or "Turing" machine, as it would be called.

"Alan had proved that there was no 'miraculous machine' that could solve all mathematical problems," Hodges explains, "but in the process he had discovered something almost equally miraculous, the idea of a universal machine that could take over the work of any machine."