In the process of a scientific education, it is easy to become caught up in the grand sense of continual progress evoked by textbooks and teachers. It becomes easy to forget that science is conducted by humans, subject to the same biases and oversights as the rest of our species. Thomas Kuhn, in his seminal work “The Structure of Scientific Revolutions,” reminds us of this human element and shows how the history of science is shaped as much by psychology as by observation.
Kuhn’s central insight is the existence of the scientific “paradigm,” a worldview that provides a set of assumptions about a given scientific field, questions which that field is expected to answer, and experimental techniques appropriate for answering those questions. Scientists, argues Kuhn, depend on paradigms to guide what he calls “normal science,” the day-to-day activity of making progress in their fields. Instead of actively seeking unexpected novelties, scientists guided by paradigms gather facts thought to be relevant to the paradigm, check the paradigm’s predictions, or determine how to apply the paradigm to a set of phenomena.
Paradigms give scientists a common vocabulary and set of techniques that allow them to make progress more rapidly than they could otherwise (or indeed, as Kuhn argues, to make progress at all). Areas of study in a pre-paradigm period have many competing schools of thought, none with widespread acceptance as the best way to look at the issues of the field or to determine what problems are important. Kuhn claims that many of the social sciences, such as economics and sociology, are still in this phase, where practitioners of a field disagree on a basic level about how that field should be defined. The physical sciences, such as astronomy and geology, have established paradigms, and practitioners with alternative views (geocentrism and young-earth creationism, for example) are not regarded as scientists at all.
Importantly, old paradigms are not immediately rejected when confronted with an observation that they cannot explain. As Kuhn writes, “novelty emerges only with difficulty, manifested by resistance, against a background provided by expectation.” He uses the discovery of the planet Uranus to illustrate this point: astronomers had noted “stars” at different points in the orbit of Uranus, but had failed to realize that these different stars were actually the same object. Sir William Herschel, nearly a century after the initial observations of Uranus, was the first see these stars as different points in the movement of a single object, and even then he classified it first as a comet, believing that all of the planets had already been discovered.
Through its trenchant analysis of past scientific developments, Kuhn’s book provides both scientists and laymen with a better understanding of the messy and convoluted process of discovery. Science never has all the answers, and even established answers are subject to change, but these characteristics are what make science such a powerful force for understanding the natural world.