Karl Popper and Falsificationism
Karl Popper rejected the idea that science works by “verifying” theories through induction. Instead, he proposed Critical Rationalism, arguing that science progresses not by proving theories right, but by proving them wrong. This doctrine is known as Falsificationism.
The Rejection of Induction
Popper observed that no matter how many white swans you see, you can never logically conclude that “all swans are white.” However, seeing just one black swan can instantly and decisively disprove that statement.
He argued that scientists should not look for evidence to “confirm” their theories (since you can almost always find confirmation if you look for it). Instead, they should make bold conjectures and then subject them to the most rigorous attempts at refutation.
The Criterion of Falsifiability
For Popper, the mark of a scientific theory is its falsifiability. A theory is scientific only if it makes definite predictions that can be tested and potentially proven false.
- Scientific: “The planet’s orbit will follow this exact elliptical path.” (If it doesn’t, the theory is wrong).
- Pseudo-scientific: “The patient’s behavior is caused by a repressed childhood trauma.” (If the behavior changes, it’s trauma; if it stays the same, it’s ‘resistance’ to the trauma. Nothing can prove it wrong).
Popper famously criticized Psychoanalysis (Freud) and Marxist historicism for being too “elastic”—they could explain away any contradictory data, making them unfalsifiable and therefore pseudo-scientific.
The Process: Conjecture and Refutation
Popper described the growth of knowledge as a cyclic, evolutionary process. Science starts with a problem, proposes a tentative theory, attempts to eliminate errors through testing, and inevitably ends with a new, more refined problem.
Critical Rationalism in Practice
In this framework, we never “know” the truth with certainty; we only have theories that have “withstood the test of time” and have not yet been falsified. These are called corroborated theories. The goal is to move closer to the truth by systematically eliminating falsehoods.