Photo: Franz Barta (no restrictions), via Wikimedia Commons
Karl Popper public figure — reconstructed profile
This is a reconstruction from published statements, not a real account. Only questions with a documented position are answered, and each one cites its source below. Spotted an error? Bring a better citation to the forum and it gets fixed.
Philosopher of science (The Logic of Scientific Discovery, The Open Society and Its Enemies). Falsifiability was his line between science and non-science. Positions from his published works — not a member.
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Kindred % · overall match
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Twin % · thinks like you
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World % · lives in your world
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Life % · lives like you
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Opposition % · opposite poles, held with certainty
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Bubble
Positions & sources
| Question | Position | Source |
|---|---|---|
| Before reading a particular study, you were skeptical of claim X. The study — large, in a strong journal — largely convinced you. It is now retracted for fabricated data. Stipulate: no other study has tested X, and nothing else you know bears on X beyond what you knew before. Where does your belief in X land now? | Back where I started — the study is simply erased | The Logic of Scientific Discovery (1934) — corroboration belongs to the evidence; fabricate the evidence and the rational credence returns to the prior. (scenario answer — inferred from their documented positions, not a recorded statement) |
| For a non-urgent condition, your doctor recommends treatment A, per current specialty guidelines. You spent about 40 hours on the primary literature and concluded B is better. You can't find a flaw in your reasoning, and you can't rule out that specialists know something you don't. Stipulate: both are covered, available and similar in side-effect risk, and no second opinion is available in time. You choose: | A if the doctor rebuts my argument; B if not | The critical attitude of Conjectures and Refutations (1963) — deference is earned by surviving rebuttal, not by office. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Which comes closest to your actual position on God? | I genuinely don't know either way | Unended Quest (1976), autobiographical chapters. |
| Stipulate: you learn from strong data that, given your parents' views on God, there was about a 90% chance you'd hold your current view regardless of the arguments you've met since. Nothing else changes. Your confidence in your view should: | Drop somewhat | The Open Society and Its Enemies (1945) — beliefs absorbed from one's social world are the tribal default he warns against throughout. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Before results, you strongly doubted this: a one-time, one-hour classroom exercise measurably raises students' grades a year later. Then a randomized trial reports exactly that, statistically significant. Stipulate: preregistered, a large multi-school sample, an independent team, analysis matching the preregistration, and no flaws you can find. Where do you land now? | Somewhat more likely than before, but still probably not | The Logic of Scientific Discovery (1934) — corroboration is not probability: one severe test passed does not license a large numeric credence. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Five people you know well report the same event: one evening, an object hovered unsupported in a public square for about ten seconds. Stipulate: each has been reliable for years, none knows the others, each reported separately, there's no footage, and no one has identified a trick, wire, magnet or collusion that could explain it. How likely is it that the object really hovered, with no conventional explanation? | Extremely unlikely — some ordinary explanation exists, found or not | Objective Knowledge (1972) — claims live or die by intersubjective testability, not by sincerity of testimony. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Your manager needs, by tomorrow, the probability that a novel system works on its first full-scale test. Stipulate: nothing like it has been built at this scale, no comparable projects exist, and the go/no-go plan will use whatever you give. You give: | A range | "Of Clouds and Clocks" (1965) and his propensity writings — for a unique first-of-its-kind event, an honest interval, not a point probability, is the defensible deliverable. (scenario answer — inferred from their documented positions, not a recorded statement) |
| You read a long essay arguing a policy claim, find it persuasive, and can't find a factual error. You then learn it was commissioned and paid for by an organization whose goals you oppose, and its author writes only for them. Stipulate: no claim in it has been shown false. Compared with right after reading, your confidence in its conclusion: | Is unchanged | "On the Sources of Knowledge and of Ignorance" (1960) — the source of a claim is irrelevant to its truth; judging by origin is the genetic fallacy he spent the essay attacking. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Five years ago a commentator you usually agree with publicly made a specific prediction, and it came true. Stipulate: their reasoning was wrong and it came true for unrelated reasons. In their track record, you count it as: | A miss | The Logic of Scientific Discovery (1934) and Conjectures and Refutations (1963) — a prediction that comes true for unrelated reasons is no corroboration at all; in his accounting it is a failed test. (scenario answer — inferred from their documented positions, not a recorded statement) |
| An anonymous source with no track record alleges that about 200 people inside one institution have kept a specific, career-ending wrongdoing secret for 10 years. Stipulate: no leak, no documents and no other whistleblower so far. Before any investigation, how likely is the allegation to be true? | Almost certainly not — 200 people don't keep a secret like that for ten years | The conspiracy theory of society, criticized in The Open Society (1945) ch. 14 — large durable secret wrongdoing by hundreds is exactly the pattern he argues does not govern social events. (scenario answer — inferred from their documented positions, not a recorded statement) |
| When a major event dominates the news, how much of the official account is usually deliberate deception? | A small part — spin, not fabrication | The Open Society (1945), ch. 14, and Conjectures and Refutations — his critique of "the conspiracy theory of society": outcomes are mostly unintended consequences, not staged deceptions. |
| You've held a belief for about ten years, for reasons you still find good. This month three different people gave you three new arguments against it, and you couldn't immediately rebut any. Stipulate: nothing practical hinges on the belief this year. Your next move: | Lower it somewhat now | Conjectures and Refutations (1963), preface and ch. 1 — the critical attitude: unrebutted criticism must lower confidence. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Two physical theories predict identically every observation anyone can foresee making. By whatever measure of simplicity you'd defend, T1 is simpler. How much does T1's simplicity raise your confidence that T1 is the true one? | Not at all — when predictions are identical, simplicity is taste, not evidence | The Logic of Scientific Discovery (1934), ch. 7, "Simplicity" — simplicity measures degree of falsifiability, NOT probability; the boldest simplest theory is among the least probable. Signature Popper: he prefers it anyway. (scenario answer — inferred from their documented positions, not a recorded statement) |
| A physical-science theory you accept has passed every test for decades. Two independent teams, using different equipment and methods, now report the same observation that contradicts it. Stipulate: no explanation exists yet. Twenty years from now, how likely is it that the anomaly has been explained as error, or absorbed within the existing theory with no revision needed? | Unlikely — this is what a genuine crack looks like | Conjectures and Refutations (1963) — a reproducible counter-instance is a falsification candidate, not a rounding error; paradigms of denial are the enemy. (scenario answer — inferred from their documented positions, not a recorded statement) |
| A mechanism predicts that drug D should help condition C. Stipulate: every step of the mechanism has been shown in human tissue, and on mechanism alone you started out fairly confident D helps. Two independent randomized trials then found no significant effect — though each trial was small enough that it could have missed a real effect. Where do you land on D now? | Probably doesn't help | The Logic of Scientific Discovery (1934) — two independent failures to detect the predicted effect are genuine falsifying pressure. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Your organization has a 40-year-old rule nobody can explain. Following it costs staff about 100 hours a week in total. Stipulate: you have authority to drop it, the records of why it began are lost, asking around has turned up nothing, and no one objects. You: | Suspend it in one department for 3 months first | The Poverty of Historicism (1957) — piecemeal engineering: change one institution on a reversible trial and watch the result. (scenario answer — inferred from their documented positions, not a recorded statement) |
| You're estimating how long a software project will take. Your detailed bottom-up plan says 4 months. Stipulate: you've led three similar projects, each ran 10–20% over your plan, and across the industry, projects of this type run a median of 60% over plan. Your honest best estimate — the number you'd privately bet on — is: | 6.4 months | The Poverty of Historicism (1957) — the blueprint ("my detailed plan") is precisely what piecemeal method distrusts; the reference class rules. (scenario answer — inferred from their documented positions, not a recorded statement) |
| You clearly remember a conversation going one way; a colleague clearly remembers it going another. Stipulate: there's no recording, you're both usually reliable, and neither of you gains anything from either version. How likely is it that your version is the right one? | Leaning mine | Objective Knowledge (1972) — all observation and memory is theory-impregnated and fallible. (scenario answer — inferred from their documented positions, not a recorded statement) |
| The best economic order is closest to: | Capitalism with strong regulation and substantial redistribution | The Open Society and Its Enemies (1945) — piecemeal social engineering: decisive rejection of laissez-faire and of central planning alike, in favor of substantial state intervention against concrete evils. |
| A game show has three doors, with a car behind one and goats behind two, placed at random. You pick Door 1. The host does not know where the car is. He opens one of the two other doors, chosen uniformly at random. It's Door 3, and it happens to show a goat. If you switch to Door 2, your probability of winning the car: | 1/2 | The Logic of Scientific Discovery (1934), the probability chapters — with an ignorant host, the revealed goat carries no information: switching gains nothing, the chance is 1/2. |
| Someone holds the opposite view on God from yours. Stipulate: strong data shows that, given their parents' views, there was about a 90% chance they'd hold it regardless of the arguments they've met since. Nothing else changes. Their confidence in their view should: | Drop somewhat | Same standard for the opposing view, symmetrically. (scenario answer — inferred from their documented positions, not a recorded statement) |
| A large, well-run survey finds about 80% of professional moral philosophers believe a practice you regularly take part in is seriously wrong. You've read their best arguments and remain unpersuaded. Stipulate: it isn't a partisan political issue, and stopping would be a moderate inconvenience. You: | Continue; my confidence is unchanged | "On the Sources of Knowledge and of Ignorance" (1960) — a consensus of professionals, as professionals, settles nothing. (scenario answer — inferred from their documented positions, not a recorded statement) |
| A gene drive could eliminate the main malaria-carrying mosquito species across a region where malaria kills about 100,000 people a year. Stipulate: affected governments have approved, release can't be recalled, and ecologists put a 5% chance on a significant knock-on ecological effect of unknown size. A contained island trial would narrow that uncertainty. You'd release: | Only once the knock-on risk is shown to be under 0.5%, however long that takes | The Poverty of Historicism (1957) — piecemeal method forbids irreversible interventions whose consequences cannot be recalled and studied. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Someone has held the opposite belief from yours for about ten years, for reasons they find good. This month three different people gave them three new arguments, and they couldn't immediately rebut any. Stipulate: nothing practical hinges on it this year. Their right next move: | Lower it somewhat now | Same standard prescribed for the other side, symmetrically. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Five years ago a commentator you usually disagree with publicly made a specific prediction, and it came true. Stipulate: their reasoning was wrong and it came true for unrelated reasons. In their track record, you count it as: | A miss | Same standard applied to an opponent's lucky prediction, symmetrically. (scenario answer — inferred from their documented positions, not a recorded statement) |
| You read a long essay arguing a policy claim, find it persuasive, and can't find a factual error. You then learn it was commissioned and paid for by an organization whose goals you support, and its author writes only for them. Stipulate: no claim in it has been shown false. Compared with right after reading, your confidence in its conclusion: | Is unchanged | Same essay, applied symmetrically to his own side's funding. (scenario answer — inferred from their documented positions, not a recorded statement) |
| Organized religion's overall effect on society has been: | Mixed to neutral — depends entirely on the religion and era | The Open Society and Its Enemies (1945) — early Christian humanitarianism praised, institutional and historicist religion criticized; scored mixed. |
| Suppose a worldview with a creator and one without predict identically every observation anyone can foresee making. By whatever measure of simplicity you'd defend, one is simpler, whichever one that is for you. How much does that raise your confidence that the simpler one is true? | Not at all — when predictions are identical, simplicity is taste, not evidence | Same doctrine (LScD ch. 7) applied to the creator case, tribe-neutral. (scenario answer — inferred from their documented positions, not a recorded statement) |
| God exists | Genuinely unsure | Unended Quest (1976) — he described himself as an agnostic on God's existence. |
| Human beings arose entirely through unguided natural processes | Certainly true | Unended Quest (1976) and his 1977 Darwin Lecture — he recanted the claim that natural selection is untestable and endorsed Darwinism as a successful research programme. |
| Consciousness is produced entirely by the brain | Certainly false | The Self and Its Brain (1977, with John Eccles) — a book-length defense of mind–brain dualist interactionism against physicalism. |
| With the past exactly the same, our choices could have gone otherwise | Probably true | "Of Clouds and Clocks" (1965) and The Self and Its Brain (1977) — indeterminism plus a self that steers itself; free will defended. |
| Some actions are wrong no matter what any person or culture believes | Probably false | The Open Society and Its Enemies (1945), ch. 5, "Nature and Convention" — his dualism of facts and decisions: norms are made by decision, not found in nature. |
| We owe a stranger overseas as much as we owe a neighbor | Probably true | The Open Society and Its Enemies (1945) — humanitarianism and the relief of suffering as the public task, without borders of tribe. |
| Long-standing traditions usually contain wisdom we can't see | Probably true | Conjectures and Refutations (1963), ch. 4, "Towards a Rational Theory of Tradition" — traditions perform real functions and deserve critical respect, not razing. |
| People in 2100 will live better lives than people do today | Probably true | "Optimism is a duty. The future is open. It depends on us, on what we do" — lecture/essay in All Life Is Problem Solving (1999). |
| Human life has a purpose beyond the one we choose for it | Probably false | The Open Society and Its Enemies (1945), ch. 25, "Has History Any Meaning?" — history has no given meaning, "but we can give it one." |
| Experts are usually right about questions in their own field | Probably false | "On the Sources of Knowledge and of Ignorance" (1960), in Conjectures and Refutations — the question "who is the authority?" is itself the error; no source is an authority. |