Kurt Gödel 
Kurt Gödel Kurt Gödel attended school in Brünn, completing his school studies in 1923. His brother Rudolf Gödel said:
Kurt entered the University of Vienna in 1923. He was taught by Furtwängler, Hahn, Wirtinger, Menger, Helly and others. As an undergraduate he took part in a seminar run by Schlick which studied Russell's book Introduction to mathematical philosophy. Olga TauskyTodd, a fellow student of Gödel's, wrote:
He completed his doctoral dissertation under Hahn's supervision in 1929 and became a member of the faculty of the University of Vienna in 1930, where he belonged to the school of logical positivism until 1938. He is best known for his proof of Gödel's Incompleteness Theorems. In 1931 he published these results in Uber formal unentscheidbare Sätze der Principia Mathematica und verwandter Systeme . He proved fundamental results about axiomatic systems showing in any axiomatic mathematical system there are propositions that cannot be proved or disproved within the axioms of the system. In particular the consistency of the axioms cannot be proved. This ended a hundred years of attempts to establish axioms to put the whole of mathematics on an axiomatic basis. One major attempt had been by Bertrand Russell with Principia Mathematica (191013). Another was Hilbert's formalism which was dealt a severe blow by Gödel's results. The theorem did not destroy the fundamental idea of formalism, but it did demonstrate that any system would have to be more comprehensive than that envisaged by Hilbert's. Gödel's results were a landmark in 20thcentury mathematics, showing that mathematics is not a finished object, as had been believed. It also implies that a computer can never be programmed to answer all mathematical questions. Gödel met Zermelo in Bad Elster in 1931. Olga TausskyTodd, who was at the same meeting, wrote:
In 1933 Hitler came to power. At first this had no effect on Gödel's life in Vienna. He had little interest in politics. However after Schlick, whose seminar had aroused Gödel's interest in logic, was murdered by a National Socialist student, Gödel was much affected and had his first breakdown. His brother Rudolf wrote
In 1934 Gödel gave a series of lectures at Princeton entitled On undecidable propositions of formal mathematical systems. At Veblen's suggestion Kleene, who had just completed his Ph.D. this at Princeton, took notes of these lectures which have been subsequently published. He returned to Vienna, married Adele Porkert in 1938, but when the war started he was fortunate to be able to return to the USA although he had to travel via Russia and Japan to do so. In 1940 Gödel emigrated to the United States and held a chair at the Institute for Advanced Study in Princeton, from 1953 to his death. He received the National Medal of Science in 1974. His work Consistency of the axiom of choice and of the generalized continuumhypothesis with the axioms of set theory (1940) is a classic of modern mathematics. His brother Rudolf, himself a medical doctor, wrote:
Towards the end of his life Gödel became convinced that he was being poisoned and, refusing to eat to avoid being poisoned, starved himself to death. In 1931, the Czechborn mathematician Kurt Gödel demonstrated that within any given branch of mathematics, there would always be some propositions that couldn't be proven either true or false using the rules and axioms ... of that mathematical branch itself. You might be able to prove every conceivable statement about numbers within a system by going outside the system in order to come up with new rules an axioms, but by doing so you'll only create a larger system with its own unprovable statements. The implication is that all logical system of any complexity are, by definition, incomplete; each of them contains, at any given time, more true statements than it can possibly prove according to its own defining set of rules. Gödel's Theorem has been used to argue that a computer can never be as smart as a
human being because the extent of its knowledge is limited by a fixed set of axioms,
whereas people can discover unexpected truths ... It plays a part in modern linguistic
theories, which emphasize the power of language to come up with new ways to express ideas.
And it has been taken to imply that you'll never entirely understand yourself, since your
mind, like any other closed system, can only be sure of what it knows about itself by
relying on what it knows about itself. The proof of Gödel's Incompleteness Theorem is so simple, and so sneaky, that it is almost embarassing to relate. His basic procedure is as follows:
With his great mathematical and logical genius, Gödel was able to find a way (for any given P(UTM)) actually to write down a complicated polynomial equation that has a solution if and only if G is true. So G is not at all some vague or nonmathematical sentence. G is a specific mathematical problem that we know the answer to, even though UTM does not! So UTM does not, and cannot, embody a best and final theory of mathematics. Although this theorem can be stated and proved in a rigorously mathematical way, what it seems to say is that rational thought can never penetrate to the final ultimate truth ... But, paradoxically, to understand Gödel's proof is to find a sort of liberation. For many logic students, the final breakthrough to full understanding of the Incompleteness Theorem is practically a conversion experience. This is partly a byproduct of the potent mystique Gödel's name carries. But, more profoundly, to understand the essentially labyrinthine nature of the castle is, somehow, to be free of it. All consistent axiomatic formulations of number theory include undecidable propositions ... Gödel showed that provability is a weaker notion than truth, no matter what axiom system is involved ... How can you figure out if you are sane? ... Once you begin to question your own sanity, you get trapped in an evertighter vortex of selffulfilling prophecies, though the process is by no means inevitable. Everyone knows that the insane interpret the world via their own peculiarly consistent logic; how can you tell if your own logic is "peculiar' or not, given that you have only your own logic to judge itself? I don't see any answer. I am reminded of Gödel's second theorem, which implies that the only versions of formal number theory which assert their own consistency are inconsistent. The other metaphorical analogue to Gödel's Theorem which I find provocative suggests that ultimately, we cannot understand our own mind/brains ... Just as we cannot see our faces with our own eyes, is it not inconceivable to expect that we cannot mirror our complete mental structures in the symbols which carry them out? All the limitative theorems of mathematics and the theory of computation suggest that once the ability to represent your own structure has reached a certain critical point, that is the kiss of death: it guarantees that you can never represent yourself totally. References:
