Why the best scientific theories are the ones most likely to be wrong

Science · Published 20 October 2026 Swipe more like this →

In short: Karl Popper argued that science does not advance by proving theories true, but by attempting to falsify them. Instead of seeking confirmation, scientists should propose bold, improbable hypotheses. If a theory survives rigorous attempts to prove it false, it becomes our best available knowledge, yet remains perpetually open to revision.

Critical rationalism, introduced by Karl Popper in his 1945 work The Open Society and Its Enemies, rejects the idea that science relies on induction. Popper argued that logic alone cannot establish empirical truth, as this leads to an infinite regress. Instead, he proposed a methodology centered on conjectures and refutations. In this view, scientific progress occurs when we subject theories to severe tests, aiming to eliminate errors rather than accumulate certainties.

Central to this framework is the criterion of falsifiability. Popper posited that for a theory to be scientific, it must prohibit certain events from occurring. If a theory is so flexible that nothing could ever contradict it, it lacks empirical content. Consequently, he famously criticized psychoanalytic theories as unscientific, contrasting them with Albert Einstein’s theory of relativity, which made risky, testable predictions—such as the deflection of light by gravity, famously verified in 1919.

Popper’s approach explicitly separates the logical structure of science from its methodology. While deductive logic is used to check consistency and derive predictions, methodology provides the rules for how scientists should behave, such as favoring theories that are more falsifiable. This is not a search for absolute truth, but a pragmatic strategy for choosing the best-tested theory currently available. As Popper noted, we should prefer the theory that has survived the most rigorous critical discussion, even if it remains technically unproven.

This philosophy has faced significant critique. Some, like Hilary Putnam, accused Popper of ignoring the role of creative insight, while others argued that his focus on falsification fails to account for how scientists actually work. Despite these debates, Popper’s rejection of 'justified true belief' as the foundation of knowledge remains a cornerstone of his work. By treating scientific knowledge as a series of conjectures that are always subject to further criticism, critical rationalism offers a way to advance understanding without succumbing to dogmatism or skepticism.

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