The Structure of Scientific Revolutions — Thomas Kuhn (1962)

Thomas Kuhn's The Structure of Scientific Revolutions introduced the concept of the "paradigm shift" — the idea that science does not progress by smooth accumulation of knowledge but through radical revolutions in fundamental assumptions. The term "paradigm shift" has become so widely used (and misused) across every field of human activity that it is one of the most consequential intellectual contributions of the 20th century.