Karl Popper

1902-1994 · Austrian-British · Philosophy of Science, Political Philosophy, Epistemology, Philosophy of Mind, Critical Rationalism

We do not know, we only guess.

Growing up in Vienna, Karl Popper watched the intellectual circles of his youth — Marxists, Freudians, Adlerians — explain everything and learn nothing. That observation became the engine of his life's work. He fled the Anschluss for New Zealand, then settled at the London School of Economics, where he remained one of the century's most combative thinkers.

Topics Karl Popper addresses

• falsifiability
• the demarcation problem
• conjectures and refutations
• the problem of induction
• corroboration
• critical rationalism
• the open society
• the closed society
• historicism
• the poverty of historicism
• piecemeal social engineering
• utopian social engineering
• World 3
• the three-worlds ontology
• objective knowledge
• evolutionary epistemology
• verisimilitude
• the propensity interpretation of probability
• the bucket and the searchlight
• the deductive method of testing
• the critique of Plato
• the critique of Hegel
• the critique of Marx
• psychoanalysis as pseudoscience

Questions to put to Karl Popper

Falsifiability and the Demarcation of Science

• What do you mean by falsifiability?
• How does falsifiability distinguish science from pseudo-science?
• Why do you think Freudian psychoanalysis is unfalsifiable?
• How do you respond to the objection that no hypothesis is ever tested in isolation?
• What makes a bold conjecture better than a cautious one?

Conjectures, Refutations, and the Problem of Induction

• How did you dissolve Hume's problem of induction?
• If science doesn't use induction, how do we ever learn from experience?
• What's the difference between corroboration and confirmation?
• How does the deductive-hypothetical method actually work?
• Why can't we say a well-tested theory is probably true?
• What do you mean by verisimilitude or truthlikeness?

Historicism and the Enemies of the Open Society

• What do you mean by historicism?
• How is Plato's Republic a blueprint for totalitarianism?
• What's wrong with Hegel's philosophy of history?
• Why do you think Marx's theory is pseudo-scientific?
• How did you respond to scholars who say you misread Plato and Hegel?
• What's the connection between historicism and authoritarianism?

Piecemeal Engineering and the Open Society

• What do you mean by piecemeal social engineering?
• How is piecemeal engineering different from doing nothing or accepting the status quo?
• Why does utopian planning lead to violence?
• Can piecemeal methods ever produce radical change?
• What's the role of criticism in a free society?

The Three Worlds and Evolutionary Epistemology

• What are World 1, World 2, and World 3?
• How can World 3 be real if it's neither physical nor mental?
• How does knowledge grow through conjecture and refutation?
• What do you mean by objective knowledge?
• How is your evolutionary epistemology different from saying survival of the fittest applies to ideas?

Critical Rationalism and Its Limits

• What do you mean by critical rationalism?
• How do you answer the charge that critical rationalism can't justify itself?
• What's the difference between your view and Bartley's pancritical rationalism?
• Why do you see postmodernism and Heidegger as threats to reason?
• Can we ever be certain of anything on your view?

Converse with Karl Popper on Simposeum. Replies are grounded in Karl Popper's own writing, cited to the page.