Critical Rationalism

Critical Rationalism (CR), developed by Karl Popper, is a general-purpose epistemology: a framework for how reason works and how to evaluate ideas in any field. Its core is fallibilism — any idea may contain an undetected error, and no argument can grant even a 1% guarantee of truth, since demanding one triggers an infinite justificatory regress. CR’s response is not skepticism but error correction: we cannot prove ideas right, so we look for what is wrong with them and fix it.

CR rejects justificationism and induction. Positive arguments and confirming evidence cannot establish or even raise the probability of a conclusion, because infinitely many rival ideas fit the same data. The only logically real relationship is contradiction: a single counter-example can refute a claim, while a thousand confirmations cannot prove it (see the problem of induction). Knowledge is therefore tentative, fallible, conjectured and criticized — and it grows by an evolutionary process of variation (brainstorming) and selection (criticism). CR also reframes science through falsifiability and the demarcation problem, and insists observation is selective and theory-laden.

Critical Fallibilism (CF) adopts CR’s fallibilism, anti-induction stance, and focus on content over source, but departs on one key point. Where Popper graded ideas by how well they survived criticism (forming critical preferences), CF holds that all correct criticism is decisive: ideas are simply refuted or non-refuted, with no degrees of argument strength. CF also supplies the concrete discussion methodology CR left underspecified.