Starting from the duck-rabbit illusion, this episode explores the origin of the phrase paradigm shift in Thomas Kuhn's 1962 book The Structure of Scientific Revolutions. Kuhn argued that knowledge does not advance by steadily stacking bricks of fact but through messy, sometimes generational revolutions. We walk through his stages: normal science as puzzle-solving within a dominant paradigm, the accumulation of anomalies, the crisis and extraordinary research that follow, the adoption of a new paradigm, and the rewriting of textbooks that smooths the whole upheaval out of the record.

We also tackle the controversial idea of incommensurability, the critiques from Donald Davidson and Martin Cohen, who called the concept an intellectual virus that feeds information cascades, and real examples from Copernicus and germ theory to Franz Boas in ant ...