Popper conceived an experiment whose analysis led to a result that he deemed absurd. Popper wrote that his reasoning was based on the Copenhagen interpretation and therefore invalidated it. Many authors who have examined Popper's analysis have found in it various technical flaws which are briefly summarized here. However, the aim of the present article is not technical. My concern is to redress logical flaws in Popper's argument: the terminology he uses is ambiguous, his analysis involves (...) counterfactual hypotheses, and it violates Bohr's complementarity principle. Therefore, the absurdity of Popper's result only confirms Bohr's approach. (shrink)

At the age of eight, Karl Popper was puzzling over the idea of infinity and by fifteen was beginning to take a keen interest in his father's well-stocked library of books. Unended Quest recounts these moments and many others in the life of one of the most influential thinkers of the twentieth century, providing an indispensable account of the ideas that influenced him most. As an introduction to Popper's philosophy, Unended Quest also shines. Popper lucidly explains (...) the central ideas in his work, making this book ideal for anyone coming to Popper's life and work for the first time. (shrink)

A sampling of the philosophical writings of Karl Popper includes discussions of rationalism, knowledge, human freedom, and the scientific method.

‘If in this book harsh words are spoken about some of the greatest among the intellectual leaders of mankind, my motive is not, I hope, to belittle them. It springs rather from my conviction that, if our civilization is to survive, we must break with the habit of deference to great men.’ - Karl Popper, from the Preface Written in political exile during the Second World War and first published in two volumes in 1945, Karl Popper’s (...) _The Open Society and Its Enemies _is one of the most influential books of all time. Hailed by Bertrand Russell as a ‘vigorous and profound defence of democracy’, its now legendary attack on the philosophies of Plato, Hegel and Marx exposed the dangers inherent in centrally planned political systems and through underground editions become an inspiration to lovers of freedom living under communism in Eastern Europe. Popper’s highly accessible style, his erudite and lucid explanations of the thoughts of great philosophers and the recent resurgence of totalitarian regimes around the world are just three of the reasons for the enduring popularity of _The Open Society and Its Enemies_ and why it demands to be read today and in years to come. (shrink)

'I want to begin by declaring that I regard scientific knowledge as the most important kind of knowledge we have', writes Sir Karl Popper in the opening essay of this book, which collects his meditations on the real improvements science has wrought in society, in politics and in the arts in the course of the twentieth century. His subjects range from the beginnings of scientific speculation in classical Greece to the destructive effects of twentieth century totalitarianism, from major (...) figures of the Enlightenment such as Kant and Voltaire to the role of science and self-criticism in the arts. The essays offer striking new insights into the mind of one of the greatest twentieth century philosophers. (shrink)

Quantum Theory and the Schism in Physics is one of the three volumes of Karl Popper’s Postscript to the Logic of scientific Discovery . The Postscript is the culmination of Popper’s work in the philosophy of physics and a new famous attack on subjectivist approaches to philosophy of science. Quantum Theory and the Schism in Physics is the third volume of the Postscript . It may be read independently, but it also forms part of Popper’s interconnected (...) argument in the Postscript . It presents Popper’s classic statement on quantum physics and offers important insights into his thinking on problems of method within science and physics as a whole. (shrink)

Described by the philosopher A.J. Ayer as a work of 'great originality and power', this book revolutionized contemporary thinking on science and knowledge. Ideas such as the now legendary doctrine of 'falsificationism' electrified the scientific community, influencing even working scientists, as well as post-war philosophy. This astonishing work ranks alongside The Open Society and Its Enemies as one of Popper's most enduring books and contains insights and arguments that demand to be read to this day.

In this long-awaited volume, Jeremy Shearmur and Piers Norris Turner bring to light Popper's most important unpublished and uncollected writings from the time of The Open Society until his death in 1994. After The Open Society: Selected Social and Political Writings reveals the development of Popper's political and philosophical thought during and after the Second World War, from his early socialism through to the radical humanitarianism of The Open Society. The papers in this collection, many of which are (...) available here for the first time, demonstrate the clarity and pertinence of Popper's thinking on such topics as religion, history, Plato and Aristotle, while revealing a lifetime of unwavering political commitment. After The Open Society illuminates the thought of one of the twentieth century's greatest philosophers and is essential reading for anyone interested in the recent course of philosophy, politics, history and society. (shrink)

_'Never before has there been so many and such dreadful weapons in so many irresponsible hands.'__ - Karl Popper, from the Preface_ _All Life is Problem Solving_ is a stimulating and provocative selection of Popper's writings on his main preoccupations during the last twenty-five years of his life. This collection illuminates Popper's process of working out key formulations in his theory of science, and indicates his view of the state of the world at the end of (...) the Cold War and after the collapse of communism. (shrink)

The way in which knowledge progresses, and especially our scientific knowledge, is by unjustified anticipations, by guesses, by tentative solutions to our problems, by conjectures. These conjectures are controlled by criticism: that is, by attempted refutations, which include severely critical tests. They may survive these tests; but they can never be positively justified: they can neither be established as certainly true nor even as 'probable'. Criticism of our conjectures is of decisive importance: by bringing out our mistakes it makes us (...) understand the difficulties of the problems which we try to solve. This is how we become better acquainted with our problem, and able to propose more mature solutions: the very refutation of a theory - that is, of a tentative solution to our problem - is always a step forward that takes us nearer the truth. And this is how we can learn from our mistakes. As we learn from our mistakes our knowledge grows, even though we may never know - that is, know for certain. Since our knowledge can grow, there can be no reason here for despair of reason. And since we can never know for certain, the can be no authority here for any claim to authority, for conceit over our knowledge, or for smugness. The essays and lectures of which this book is composed apply this thesis to many topics, ranging from problems of the philosophy and history of the physical and social sciences to historical and political problems. (shrink)

Popper formulates and explains his non-justificationist theory of knowledge. Science--empirical science--aims at true explanatory theories, yet it can never prove, finally establish, or justify any of its theories as true, not even if it is in fact a true theory. Science must continue to question and criticize all its theories, even those which happen to be true.

Bertrand Russell described this study, with its companion volume on Hegel and Marx, as 'a work of first-class importance which ought to be widely read for its masterly criticism of the enemies of democracy, ancient and modern. His (Popper's) attack on Plato, while unorthodox, is in my opinion thoroughly justified. His analysis of Hegel is deadly. Marx is dissected with equal acumen, and given his due share of responsibility for modern misfortunes. The book is a vigorous and profound defence (...) of democracy, timely, very interesting, and very well written'. 'A powerful and important book. It is a criticism of a set of dogmas which underlie the most influential political theories, and in consequence powerfully affect the actual conduct of human affairs. Dr Popper writes with extreme clarity and vigour. His studies in Greek history and Greek thought have obviously been profound and original. Platonic exegesis will never be the same again. Nor, I think, will Marxist exegesis. Readers should not miss studying the notes collected at the end of the two volumes.' - Gilbert Ryle, Mind. (shrink)

The essays in this volume represent an approach to human knowledge that has had a profound influence on many recent thinkers. Popper breaks with a traditional commonsense theory of knowledge that can be traced back to Aristotle. A realist and fallibilist, he argues closely and in simple language that scientific knowledge, once stated in human language, is no longer part of ourselves but a separate entity that grows through critical selection.

Written in political exile during the Second World War and first published in 1945, Karl Popper's The Open Society and Its Enemies is one of the most influential books of the twentieth century. Hailed by Bertrand Russell as a 'vigorous and profound defence of democracy', its now legendary attack on the philosophies of Plato, Hegel and Marx exposed the dangers inherent in centrally planned political systems. Popper's highly accessible style, his erudite and lucid explanations of the thought (...) of great philosophers and the recent resurgence of totalitarian regimes around the world are just three of the reasons for the enduring popularity of The Open Society and Its Enemies , and for why it demands to be read both today and in years to come. This is the first of two volumes of The Open Society and Its Enemies. (shrink)

Hailed on publication in 1957 as "probably the only book published this year that will outlive the century," this is a brilliant of the idea that there are ...

Realism and the Aim of Science is one of the three volumes of Karl Popper’s Postscript to the Logic of scientific Discovery. The Postscript is the culmination of Popper’s work in the philosophy of physics and a new famous attack on subjectivist approaches to philosophy of science. Realism and the Aim of Science is the first volume of the Postcript . Popper here formulates and explains his non-justificationist theory of knowledge: science aims at true explanatory theories, (...) yet it can never prove, or justify, any theory to be true, not even if is a true theory. Science must continue to question and criticise all its theories, even those that happen to be true. Realism and the Aim of Science presents Popper’s mature statement on scientific knowledge and offers important insights into his thinking on problems of method within science. (shrink)

One of the most influential thinkers of the 20th century, Sir Karl Popper here examines the problems connected with human freedom, creativity, rationality and the relationship between human beings and their actions. In this illuminating series of papers, Popper suggests a theory of mind-body interaction that relates to evolutionary emergence, human language and what he calls "the three worlds." Rene; Descartes first posited the existence of two worlds--the world of physical bodies and the world of mental states. (...) Popper argues for the existence of "world 3" which comprises the products of our human minds. He examines the interaction between mental states--hopes, needs, plans, ideologies or hypotheses--and the physical states of our brain. Popper forcefully argues against the materialism forwarded by many philosophers which denies the existence of mental states. Instead, he demonstrates that the problem of the interaction between mental and physical states remains unresolved. Knowledge and the Body-Mind Problem is based on Popper's never-before published lectures at Emory University in 1969. Popper has extensively revised the lectures but has retained their accessible format. He has also incorporated some of the discussions which followed the lectures, providing an engaging exchange between the philosopher and his audience. (shrink)

A brief historical comment on scientific knowledge as Socratic ignorance -- Some critical comments on the text of this book, particularly on the theory of truth Exposition [1933] -- Problem of Induction (Experience and Hypothesis) -- Two Fundamental Problems of the Theory of Knowledge -- Formulation of the Problem -- The problem of induction and the problem of demarcation -- Deductivtsm and Inductivism -- Comments on how the solutions are reached and preliminary presentation of the solutions -- Rationalism and empiricism-deductivism (...) and inductivism -- The possibility of a deductivist psychology of knowledge -- The Problem of Induction -- The infinite regression (Hume's argument) --The inductivist positions -- The Normal-Statement Positions -- The normal-statement positions: naive inductivism, strict positivism and apriorism -- Critique of strict positivism - twofold transcendence of natural laws -- The transcendental method - presentation of apriorism -- Critique of apriorism -- Kant and Fries -- Supplement to the critique of apriorism. (Psychologism and transcendentalism in Kant and Fries.-On the question of the empirical basis.) -- Probability Positions -- The probability positions - subjective belief in probability -- Statements about the objective probability of events -- Probability as an objective degree of validity of universal empirical statements -- One way of more closely defining the concept of the probability of a hypothesis (primary and secondary probability of hypotheses). The concept of simplicity -- The concept of the corroboration of a hypothesis - positivist, pragmatist and probabilistic interpretations of the concept of corroboration -- The infinite regression of probability statements -- Pseudo-Statement Positions -- The pseudo-statement positions: new formulation of the problem -- Natural laws as "instructions for the formation of statements" -- "True - false" or "useful - useless"? Consistent pragmatism --Difficulties of consistent pragmatism -- Tool and schema as purely pragmatic constructs -- Natural laws as propositional functions -- Conventionalism -- The pseudo-statement positions will temporarily be put away: conventionalism -- The three interpretations of axiomatic systems. (The circle of problems surrounding conventionalism) -- Conventionalist implicit and explicit definitions Propositional function and propositional equation -- Conventionalist propositional equations as tautological general implications -- Can axiomatic-deductive systems also be understood as consequence classes of pure propositional functions (of pseudo-statements)? -- The coordinative definitions of empiricism: synthetic general implications -- Conventionalist and empiricist interpretations, illustrated by the example of applied geometry -- Strictly Universal Statements and Singular Statements -- Implication and general implication -- General implication and the distinction between strictly universal and singular statements -- Universal concept and individual concept-class and element -- Strictly universal statements-the problem of induction and the problem of universals -- Comments on the problem of universals -- Back to the Pseudo-Statement Positions -- Return to the discussion of the pseudo-statement positions -- Symmetry or asymmetry in the evaluation of natural laws? -- The negative evaluation of universal statements. Critique of the strictly symmetrical interpretation of pseudo-statements -- An infinite regression of pseudo-statements -- An apriorist pseudo-statement position -- Interpretation of the critique up to this point; comments on the unity of theory and practice -- A last chance for the pseudo-statement positions -- Pseudo-Statement Positions and the Concept of Meaning -- The concept of meaning and logical positivism -- The concept of meaning and the demarcation problem-the fundamental thesis of inductivism -- Critique of the inductivist dogma of meaning -- Fully decidable and partially decidable empirical statements-the antinomy of the knowability of the world. (Conclusion of the critique of the pseudo-statement positions.) -- The dialectical and the transcendental corroboration of the solution -- Is the problem of induction solved? (shrink)

The World of Parmenides is a unique collection of essays that not only explores the complexity of ancient Greek thought, but also reveals Popper's engagement with Presocratic philosophy and the enlightenment he experienced in reading Parmenides. It includes writings on Greek science, philosophy and history and demonstrates Popper's life-long fascination with the presocratic philosophers, in particular Parmenides, Xenophanes and Heraclitus.

Bertrand Russell described this study, with its companion volume on Plato, as a work of first-class importance. Karl Popper writes with extreme clarity and vigour. Platonic history will never be the same again.

With a new foreword by_ Scott Austin_ _'I hope that these essays may illustrate the thesis that all history is or should be the history of problem situations, and that in following this principle we may further our understanding of the Presocratics and other thinkers of the past. The essays also try to show the greatness of the early Greek philosophers, who gave Europe its philosophy, its science, and its humanism.'_ _- Karl Popper, from the preface _ _The (...) World of Parmenides_ is a brilliant exploration of the complexity of ancient Greek thought and science by one of the twentieth century’s leading philosophers. It reveals the great importance of Presocratic philosophy to Popper’s thought as a whole and shows the profound enlightenment he experienced reading not only Parmenides but the wider world of Greek science and philosophy including Xenophanes and Heraclitus. Edited by Arne F. Petersen, Associate Professor in the Faculty of Humanities, University of Copenhagen. (shrink)

Karl Popper’s philosophy of science provides a foundation for a theory of literary interpretation that avoids the pitfalls of contemporary theories. This study outlines the approach and applies it to challenging works from the Gospel of Mark to Patrick Modiano.

On the Sources of Knowledge and Ignorance;.

The rational understanding of the quantum theory achieved by de Broglie is contrasted with the Copenhagen emphasis on “the quantum postulate with its inherent ‘irrationality’” (Niels Bohr, Ref. 1).

The way in which knowledge progresses, and especially our scientific knowledge, is by unjustified (and unjustifiable) anticipations, by guesses, by tentative solutions to our problems, by conjectures. These conjectures are controlled by criticism: that is, by attempted refutations, which include severely critical tests. They may survive these tests; but they can never be positively justified: they can neither be established as certainly true nor even as 'probable' (in the sense of the probability calculus). Criticism of our conjectures is of decisive (...) importance: by bringing out our mistakes it makes us understand the difficulties of the problems which we try to solve. This is how we become better acquainted with our problem, and able to propose more mature solutions: the very refutation of a theory - that is, of a tentative solution to our problem - is always a step forward that takes us nearer the truth. And this is how we can learn from our mistakes. As we learn from our mistakes our knowledge grows, even though we may never know - that is, know for certain. Since our knowledge can grow, there can be no reason here for despair of reason. And since we can never know for certain, the can be no authority here for any claim to authority, for conceit over our knowledge, or for smugness. The essays and lectures of which this book is composed apply this thesis to many topics, ranging from problems of the philosophy and history of the physical and social sciences to historical and political problems. (shrink)

One of the most important books of the twentieth century, Karl Popper's The Open Society and Its Enemies is an uncompromising defense of liberal democracy and a powerful attack on the intellectual origins of totalitarianism. Popper was born in 1902 to a Viennese family of Jewish origin. He taught in Austria until 1937, when he emigrated to New Zealand in anticipation of the Nazi annexation of Austria the following year, and he settled in England in 1949. Before (...) the annexation, Popper had written mainly about the philosophy of science, but from 1938 until the end of the Second World War he focused his energies on political philosophy, seeking to diagnose the intellectual origins of German and Soviet totalitarianism. The Open Society and Its Enemies was the result. An immediate sensation when it was first published in two volumes in 1945, Popper's monumental achievement has attained legendary status on both the Left and Right and is credited with inspiring anticommunist dissidents during the Cold War. Arguing that the spirit of free, critical inquiry that governs scientific investigation should also apply to politics, Popper traces the roots of an opposite, authoritarian tendency to a tradition represented by Plato, Marx, and Hegel. In a substantial new introduction written for this edition, acclaimed political philosopher Alan Ryan puts Popper's landmark work in biographical, intellectual, and historical context. Also included is a personal essay by eminent art historian E.H. Gombrich, in which he recounts the story of the book's eventual publication despite numerous rejections and wartime deprivations. (shrink)

“There could be no fairer destiny for any. . . theory than that it should point the way to a more comprehensive theory in which it lives on, as a limiting case.” ALBERT EINSTEIN..

In _The Lesson of this Century_ Popper's purpose is to warn us against the increasing violence and egoism of our society. What solutions can we offer to the problems of the environment, demography and corruption? How can we prevent the violence our society engenders? How can we preserve our democratic system while at the same time paving the way for global peace? Popper believes that the philosopher has a duty to intervene in politics and he utters a clear (...) call to all of us to recognise our responsibilities. He reminds us that it is our actions which will create the world of tomorrow. The interviews in this volume were originally given to the Italian journalist Giancarlo Bosetti. The volume also includes the transcript of an interview about the moral dangers of television not previously available in English. (shrink)