Frank P. Ramsey

Frank Plumpton Ramsey ( born February 22, 1903 in Cambridge, † January 19, 1930 ) was a British mathematician and logician.

Life and work

Ramsey was born in Cambridge, where his father - also a mathematician - President of Magdalene College was. He attended college in Winchester, before he returned to Cambridge to study mathematics at Trinity College. He was in the Tripos (very competitive math tests) "Senior Wrangler ", at that time the highest award for a math student at Cambridge.

Ramsey's superior intelligence impressed many academics in Cambridge. He was well-read in various fields and was interested in almost everything. Politically, he was left-wing and (in the words of his wife) a " militant atheist ". In a conversation with Charles Kay Ogden, he expressed his desire to learn German. Ogden gave him a dictionary to a German grammar and an abstruse philosophical treatise and said to him: "Use the grammar and the dictionary; Come back and tell us what you think about it. " About a week later he had not only learned German, but had put forward objections to the theories of the treatise. He used his newly acquired ability to read Ludwig Wittgenstein's Tractatus Logico - Philosophicus, that the 1918 just completed it.

Reading deeply impressed him. He translated a large part of it into English and published a first review in the philosophical journal Mind. In 1923, he traveled for a short time after Austria and discussed with Wittgenstein, who was working at the time as a village teacher. 1924 included a further visit in Austria for psychoanalysis with Theodor Reik in Vienna and further visits to Wittgenstein. Some philosophers think Ramsey would have lived longer publicly just such a status as a philosopher reached as Wittgenstein. In fact, Ramsey's criticism influenced, besides discussions with Piero Sraffa, in which Ramsey was involved, Wittgenstein's later philosophy in the " Philosophical Investigations ". Other philosophical works of Ramsey dealing with the character of laws of nature and the philosophy of science.

Apparently torn between the events of the just concluded First World War and under the influence of a genius like Wittgenstein, he wrote at this time to his mother: " We really live in a great time for thinking, with Einstein, Freud and Wittgenstein all alive, and all in Germany or Austria, Those foes of civilization "( German: " We really do live in philosophical great times with Einstein, Freud and Wittgenstein still alive among us, all in Germany and Austria, these enemies of civilization " ).

Back in England he was appointed at the young age of 21 years as a Fellow at King's College, where he was " Director of Studies in Mathematics".

His discussions with Wittgenstein also meant that he could greatly simplify the sentences of the monumental " Principia Mathematica " by Bertrand Russell and Alfred North Whitehead, who wanted to return the whole of mathematics to logic, led: he underlined that logical propositions are tautologies in the sense Wittgenstein would have to be, pointing out that only logical and semantic paradoxes do not need to be discussed. He showed that the reducibility used by them was unnecessary.

The two existence theorems, which were erected by Ramsey in his work "On a problem of formal logic ," acted as a trigger for further work in the field of graph theory and combinatorics, and are known as Ramsey 's theorem. The resulting therefrom in combinatorics under the hand of Paul Erdős and other body called Ramsey theory. He proved his theorem ( Ramsey's theorem ) as an aid in his essay, in which he shows the decidability of the decision problem of a specific fragment ( Bernays - Schönfinkel - Ramsey class) of first-order logic. The American logician Alonzo Church proved later that the general decision problem of first-order logic is undecidable.

Ramsey, who was a friend of John Maynard Keynes, published two important economic work. Add A contribution to the theory of taxation it is 1927, the Ramsey rule, which is an important contribution to the theory of optimal taxation. In his work, A mathematical theory of saving from 1928 he studied with the aid of the calculus of variations, how much to invest an economy should consume rather than to make them up to grow in the future. This difficult work was admired by John Maynard Keynes and later by Paul Samuelson and is the starting point of the "optimal accumulation", developed by Tjalling Koopmans and David Cass. Just as important as the results were his methods (dynamic optimization).

Ramsey criticized Keynes's theory of probability as inductive logic so sharp that she gave this. In " Truth and probability" he was also a theory of probability measure of how much someone is convinced of a view ( decision theory).

On January 19, 1930 Frank Plumpton Ramsey died at age 26 from the effects of abdominal surgery, in which he was infected with hepatitis ( he also had life liver problems). He was married in 1925 and had two daughters. His brother Michael (1904-1988) was as Lord Ramsey Archbishop of Canterbury - both remained faithful despite Ramsey's atheism the church.

Works (selection)

• The Foundations of mathematics and other logical essays, RB Braithwaite ed, London, Routledge and Keegan 1931 German translation: Ramsey Basics: Essays on Philosophy, Logic, Mathematics and Economics, Stuttgart, Frommann - Holzboog 1980