Thomas Kuhn was a physics student at Harvard when a teaching assignment changed his life. He had to give an experimental course on science for beginners, which exposed him to centuries-long battles over competing scientific theories and world views. A fire had been lit.

A deepening fascination with these scientific clashes inspired him to scrap his original career plans. Instead, he aimed to chronicle how these revolutions played out across the ages. In the process, he would construct a new history of science.

The resulting book, 1962’s The Structure of Scientific Revolutions, became a sensation. It helped make Kuhn “the most important, and the most famous, historian and philosopher of science”, according to a biography published by the American National Academy of Sciences.

One reason was timing. The ‘Space Race’ unfolded new possibilities for human exploration of the cosmos. A revolution in nuclear physics allowed rival superpowers to develop hydrogen bombs, stoking fears of a nuclear doomsday. This helped make Kuhn’s book a must-read.

So what’s the fuss about? The first thing to note is Kuhn’s concept of ‘paradigms’ (a word he helped to popularize). He defines them as universally recognized achievements that unify scientists around a prevailing model and/or theory.

Kuhn’s model of how science advances involves two alternating speeds. Science can move in tiny increments through researchers engaged in “normal science.” At other times, there are extraordinary leaps offered by the leaders of a would-be revolution.

Even when a breakthrough turns out to be flawed, the most successful paradigms can sustain centuries of progressive scientific research. This is the “normal science” period in which scientists are happy to work within the norms of the paradigm rather than seeking to overturn it.

Kuhn made a shocking insight by revealing that many scientists – often perceived as explorers of new frontiers – actually move to suppress new discoveries and theories that challenge the paradigm. Why? Because going against the paradigm can be a career-threatening move.

Yet when enough challenges appear in the form of new discoveries and scientific anomalies, it can trigger a crisis in the paradigm. These findings can no longer be ignored or explained away. Instead, they pave the way for “extraordinary science” and a new revolutionary model.

One of Kuhn’s key examples of paradigm change is the ‘battles over the cosmos’ that saw a shift from the Ptolemaic to the Copernican understanding of the universe. Let’s dive right into this in Part 2...