Lakatos was born Imre (Avrum) Lipsitz to a Jewish family in Debrecen, Hungary, in 1922. He received a degree in mathematics, physics, and philosophy from the University of Debrecen in 1944. He avoided Nazi persecution of Jews by changing his name to Imre Molnár. His mother and grandmother died in Auschwitz. He became an active communist during the Second World War. He changed his last name once again to Lakatos (Locksmith) in honor of Géza Lakatos.

After the war, from 1947 he worked as a senior official in the Hungarian ministry of education. He also continued his education with a PhD at Debrecen University awarded in 1948, and also attended György Lukács's weekly Wednesday afternoon private seminars. He also studied at the Moscow State University under the supervision of Sofya Yanovskaya in 1949. When he returned, however, he found himself on the losing side of internal arguments within the Hungarian communist party and was imprisoned on charges of revisionism from 1950 to 1953. More of Lakatos' activities in Hungary after World War II have recently become known.

After his release, Lakatos returned to academic life, doing mathematical research and translating George Pólya's How to Solve It into Hungarian. Still nominally a communist, his political views had shifted markedly and he was involved with at least one dissident student group in the lead - up to the 1956 Hungarian Revolution.

After the Soviet Union invaded Hungary in November 1956, Lakatos fled to Vienna, and later reached England. He received a doctorate in philosophy in 1961 from the University of Cambridge. The book Proofs and Refutations: The Logic of Mathematical Discovery, published after his death, is based on this work.

Lakatos never obtained British Citizenship. In 1960 he was appointed to a position in the London School of Economics, where he wrote on the philosophy of mathematics and the philosophy of science. The LSE philosophy of science department at that time included Karl Popper, Joseph Agassi and John Watkins. It was Agassi who first introduced Lakatos to Popper under the rubric of his applying a fallibilist methodology of conjectures and refutations to mathematics in his Cambridge PhD thesis.

With co-editor Alan Musgrave, he edited the highly cited Criticism and the Growth of Knowledge, the Proceedings of the International Colloquium in the Philosophy of Science, London, 1965. Published in 1970, the 1965 Colloquium included well - known speakers delivering papers in response to Thomas Kuhn's "The Structure of Scientific Revolutions".

Lakatos remained at the London School of Economics until his sudden death in 1974 of a brain haemorrhage, aged just 51. The Lakatos Award was set up by the school in his memory.

In January 1971 he became editor of the internationally prestigious British Journal for the Philosophy of Science until his death in 1974, after which it was then edited jointly for many years by his LSE colleagues John Watkins and John Worrall, Lakatos's ex-research assistant.

His last LSE lectures in scientific method in Lent Term 1973 along with parts of his correspondence with his friend and critic Paul Feyerabend have been published in For and Against Method.

Lakatos and his colleague Spiro Latsis organised an international conference devoted entirely to historical case studies in Lakatos's methodology of research programmes in physical sciences and economics, to be held in Greece in 1974, and which still went ahead following Lakatos's death in February 1974. These case studies in such as Einstein's relativity programme, Fresnel's wave theory of light and neoclassical economics, were published by Cambridge University Press in two separate volumes in 1976, one devoted to physical sciences and Lakatos's general programme for rewriting the history of science, with a concluding critique by his great friend Paul Feyerabend, and the other devoted to economics.

Lakatos' philosophy of mathematics was inspired by both Hegel's and Marx' dialectic, by Karl Popper's theory of knowledge, and by the work of mathematician George Polya.

The 1976 book Proofs and Refutations is based on the first three chapters of his four chapter 1961 doctoral thesis Essays in the logic of mathematical discovery. But its first chapter is Lakatos’s own revision of its chapter 1 that was first published as Proofs and Refutations in four parts in 1963-4 in The British Journal for the Philosophy of Science. It is largely taken up by a fictional dialogue set in a mathematics class. The students are attempting to prove the formula for the Euler characteristic in algebraic topology, which is a theorem about the properties of polyhedra, namely that for all polyhedra the number of their (V)ertices minus the number of their (E)dges plus the number of their (F)aces is 2:  (V – E + F = 2). The dialogue is meant to represent the actual series of attempted proofs which mathematicians historically offered for the conjecture, only to be repeatedly refuted by counterexamples. Often the students 'quote' famous mathematicians such as Cauchy.

What Lakatos tried to establish was that no theorem of informal mathematics is final or perfect. This means that we should not think that a theorem is ultimately true, only that no counterexample has yet been found. Once a counterexample, i.e. an entity contradicting/not explained by the theorem is found, we adjust the theorem, possibly extending the domain of its validity. This is a continuous way our knowledge accumulates, through the logic and process of proofs and refutations. (If axioms are given for a branch of mathematics, however, Lakatos claimed that proofs from those axioms were tautological, i.e. logically true.)

Lakatos proposed an account of mathematical knowledge based on the idea of heuristics. In Proofs and Refutations the concept of 'heuristic' was not well developed, although Lakatos gave several basic rules for finding proofs and counterexamples to conjectures. He thought that mathematical 'thought experiments' are a valid way to discover mathematical conjectures and proofs, and sometimes called his philosophy 'quasi - empiricism'.

However, he also conceived of the mathematical community as carrying on a kind of dialectic to decide which mathematical proofs are valid and which are not. Therefore he fundamentally disagreed with the 'formalist' conception of proof which prevailed in Frege's and Russell's logicism, which defines proof simply in terms of formal validity.

On its first publication as a paper in The British Journal for the Philosophy of Science in 1963-4, Proofs and Refutations became highly influential on new work in the philosophy of mathematics, although few agreed with Lakatos' strong disapproval of formal proof. Before his death he had been planning to return to the philosophy of mathematics and apply his theory of research programmes to it. Lakatos, Worrall and Zahar use Poincaré (1893) to answer one of the major problems perceived by critics, namely that the pattern of mathematical research depicted in Proofs and Refutations does not faithfully represent most of the actual activity of contemporary mathematicians.

Lakatos' contribution to the philosophy of science was an attempt to resolve the perceived conflict between Popper's falsificationism and the revolutionary structure of science described by Kuhn. Popper's theory as often (inaccurately) reported implied that scientists should give up a theory as soon as they encounter any falsifying evidence, immediately replacing it with increasingly 'bold and powerful' new hypotheses. However, Kuhn described science as consisting of periods of normal science in which scientists continue to hold their theories in the face of anomalies, interspersed with periods of great conceptual change. Popper acknowledged that excellent new theories may be inconsistent with apparently empirically well supported older theories. For example, he pointed out in Objective Knowledge that "in Newton's theory Kepler's laws are only approximately valid – that is, strictly invalid – if we take into account the mutual attraction between the planets", so that (in precise terms) Newton's theories were inconsistent with Kepler's third law. However, whereas Kuhn implied that good scientists ignored or discounted evidence against their theories Popper regarded counter evidence as something to be dealt with, either by explaining it, or eventually modifying the theory. Popper was not describing actual behaviour of scientists, but what a scientist should do. Kuhn was mostly describing actual behaviour.

Lakatos sought a methodology that would harmonize these apparently contradictory points of view, a methodology that could provide a rational account of scientific progress, consistent with the historical record.

For Lakatos, what we think of as a 'theory' may actually be a succession of slightly different theories and experimental techniques developed over time, that share some common idea, or what Lakatos called their ‘hard core’. Lakatos called such changing collections 'Research Programmes'. The scientists involved in a programme will attempt to shield the theoretical core from falsification attempts behind a protective belt of auxiliary hypotheses. Whereas Popper was generally regarded as disparaging such measures as 'ad hoc', Lakatos wanted to show that adjusting and developing a protective belt is not necessarily a bad thing for a research programme. Instead of asking whether a hypothesis is true or false, Lakatos wanted us to ask whether one research programme is better than another, so that there is a rational basis for preferring it. He showed that in some cases one research programme can be described as progressive while its rivals are degenerating. A progressive research programme is marked by its growth, along with the discovery of stunning novel facts, development of new experimental techniques, more precise predictions, etc. A degenerating research program is marked by lack of growth, or growth of the protective belt that does not lead to novel facts.

Lakatos claimed that he was extending Popper's ideas, which had themselves developed over time. He contrasted Popper, the crude falsificationist, who existed only in the minds of critics and followers who had not understood Popper's writings, Popper1, the author of what Popper actually wrote, and Popper2, who was supposed to be Popper as reinterpreted by his pupil Lakatos, though many commentators believe that Popper2 just is Lakatos. The idea that it is often not possible to show decisively which of two theories or research programmes is better at a particular point in time whereas subsequent developments may show that one is 'progressive' while the other is 'degenerating', and therefore less acceptable, was a major contribution both to philosophy of science and to history of science. Whether it was Popper's idea or Lakatos' idea, or, most likely, a combination, is of less importance.

Lakatos was following Pierre Duhem's idea that one can always protect a cherished theory (or part of one) from hostile evidence by redirecting the criticism toward other theories or parts thereof. (Confirmation holism and Duhem - Quine thesis). This difficulty with falsificationism had been acknowledged by Popper.

Falsificationism, (Popper's theory), proposed that scientists put forward theories and that nature 'shouts NO' in the form of an inconsistent observation. According to Popper, it is irrational for scientists to maintain their theories in the face of Nature's rejection, yet this is what Kuhn had described them as doing. But for Lakatos, "It is not that we propose a theory and Nature may shout NO rather we propose a maze of theories and nature may shout INCONSISTENT". This inconsistency can be resolved without abandoning our Research Programme by leaving the hard core alone and altering the auxiliary hypotheses. One example given is Newton's three laws of motion. Within the Newtonian system (research programme) these are not open to falsification as they form the programme's hard core. This research programme provides a framework within which research can be undertaken with constant reference to presumed first principles which are shared by those involved in the research programme, and without continually defending these first principles. In this regard it is similar to Kuhn's notion of a paradigm.

Lakatos also took the view that a research programme contained 'methodological rules', some that instruct on what paths of research to avoid (he called this the 'negative heuristic') and some that instruct on what paths to pursue (he called this the 'positive heuristic').

Lakatos claimed that not all changes of the auxiliary hypotheses within research programmes (Lakatos calls them 'problem shifts') are equally as acceptable. He took the view that these 'problem shifts' can be evaluated both by their ability to explain apparent refutations and by their ability to produce new facts. If it can do this then Lakatos claims they are progressive. However if they do not, if they are just 'ad-hoc' changes that do not lead to the prediction of new facts, then he labels them as degenerate.

Lakatos took the view that if a research programme is progressive, then it is rational for scientists to keep changing the auxiliary hypotheses in order to hold on to it in the face of anomalies. However, if a research programme is degenerate, then it faces danger from its competitors: it can be 'falsified' by being superseded by a better (i.e. more progressive) research programme. This is what he says is happening in the historical periods Kuhn describes as revolutions and what makes them rational as opposed to mere leaps of faith (as he considered that Kuhn took them to be).

According to the demarcation criterion of pseudoscience originally proposed by Lakatos, a theory is pseudoscientific if it fails to make any novel predictions of previously unknown phenomena, in contrast with scientific theories, which predict novel fact(s). Progressive scientific theories are those which have their novel facts confirmed and degenerate scientific theories are those whose predictions of novel facts are refuted. As he put it:

"A given fact is explained scientifically only if a new fact is predicted with it.... The idea of growth and the concept of empirical character are soldered into one." The Methodology of Scientific Research Programmes, 1978.

Lakatos's own key examples of pseudoscience were Ptolemaic astronomy, Velikovsky's planetary cosmogony, Freudian psychoanalysis, 20th century Soviet Marxism, Lysenko's biology, Bohr's Quantum Mechanics post 1924, astrology, psychiatry, sociology and neo - classical economics. And in his 1973 LSE Scientific Method Lecture 1 he also claimed that "nobody to date has yet found a demarcation criterion according to which Darwin can be described as scientific".

Almost 20 years after Lakatos's 1973 'challenge' on the scientificity of Darwin, in her 1991 The Ant and the Peacock, LSE lecturer and ex - colleague of Lakatos, Helena Cronin, attempted to establish that Darwinian theory was empirically scientific in respect of at least being supported by evidence of likeness in the diversity of life forms in the world, allegedly explained by descent with modification. She concluded that "our usual idea of corroboration as requiring the successful prediction of novel facts... Darwinian theory was not strong on temporally novel predictions". She was equivocal about whether it did or did not make any novel predictions, only saying " For the most part this evidence was already well known, thoroughly documented by pre - Darwinian natural history. [Italics added]" Cronin did not state what other part of the evidence was not already well known, but did then assert that it was scientific on the weaker Zahar criterion of providing independent novel explanation of old already well known facts. However, she failed to demonstrate that it provided any confirmed nomological - deductive explanation of any old facts of likeness within evolutionary diversity, making an assertion that it did so, without proof.

In August 1972, a case study of the methodology of neoclassical economics by Lakatos's London School of Economics colleague Spiro Latsis published in The British Journal for the Philosophy of Science found Milton Friedman's methodology to be 'pseudo - scientific' in terms of Lakatos's evaluative philosophy of science, according to which the demarcation between scientific and pseudo - scientific theories consists of their at least predicting testable empirical novel facts or not. Latsis claimed that Friedman's instrumentalist methodology of neoclassical economics had never predicted any novel facts. In its defense in a three page letter to Latsis in December 1972, Friedman counter - claimed that the neoclassical monopoly competition model had in fact shown empirical progress by predicting phenomena not previously observed that were also subsequently confirmed by empirical evidence. But he did not identify any specific economic phenomenon as an example of any such successfully predicted positive novel fact.

In early 1973, as Editor of the Journal, Lakatos invited Friedman to submit a discussion note based on his December 1972 letter to Latsis for publication in a symposium on the issue of the scientific status or not of neoclassical economics. Lakatos even assured Friedman he would have the last word. But Friedman never took up Lakatos's invitation. Three years later, in 1976, Friedman was awarded the Nobel Prize for Economics "for his achievements in the fields of consumption analysis, monetary history and theory and for his demonstration of the complexity of stabilization policy".

In his 1973 monograph History of Science and Its Rational Reconstructions Lakatos proposed a dialectical historiographical meta - method for evaluating different theories of scientific method, namely by means of their comparative success in explaining the actual history of science and scientific revolutions on the one hand, whilst on the other providing a historiographical framework for rationally reconstructing the history of science as anything more than merely inconsequential rambling. The paper started with his now renowned dictum “Philosophy of science without history of science is empty; history of science without philosophy of science is blind.”

However neither Lakatos himself nor his collaborators ever completed the first part of this dictum by showing that in any scientific revolution the great majority of the relevant scientific community converted just when Lakatos’s criterion – one programme successfully predicting some novel facts whilst its competitor degenerated - was satisfied. Indeed for the historical case studies in his 1970 Criticism and the Methodology of Scientific Research Programmes he had openly admitted as much, commenting 'In this paper it is not my purpose to go on seriously to the second stage of comparing rational reconstructions with actual history for any lack of historicity.'

Paul Feyerabend argued that Lakatos's methodology was not a methodology at all, but merely "words that sound like the elements of a methodology." He argued that Lakatos's methodology was no different in practice from epistemological anarchism, Feyerabend's own position. He wrote in Science in a Free Society (after Lakatos's death) that:

Lakatos realized and admitted that the existing standards of rationality, standards of logic included, were too restrictive and would have hindered science had they been applied with determination. He therefore permitted the scientist to violate them (he admits that science is not "rational" in the sense of these standards). However, he demanded that research programmes show certain features in the long run — they must be progressive.... I have argued that this demand no longer restricts scientific practice. Any development agrees with it.

Lakatos and Feyerabend planned to produce a joint work in which Lakatos would develop a rationalist description of science and Feyerabend would attack it. According to Feyerabend, Lakatos's unexpected demise threw Feyerabend into a depression.