Last week the press focused on JD Vance, Donald Trump’s surprise choice for vice presidential candidate, who grew up in working-class Middletown, Ohio. July 18 was the birthday of another famous Ohioan – Thomas Kuhn, who wrote one of the bestselling philosophy books of the last century, The Structure of Scientific Revolutions, first published in 1962.
Kuhn began as a physicist working on radar and then on quantum physics, before turning to the history of science. He became interested in the early history of thermodynamics. This led to his philosophical speculations about the nature of science and his notion of a paradigm shift.
The straightforward view, that many scientists still hold, is that there is a reality out there and the point of science is to try to describe it and make predictions about it: new theories supersede old ones, and better fit the evidence, and scientists are forever edging closer to an accurate description of reality. Kuhn rejected this account.
His distinctive contribution was to describe different phases of scientific research over time. In periods of what he called normal science, scientists engage in problem-solving within an agreed paradigm.
Kuhn was notoriously vague about what a paradigm was, but roughly it’s a broad intellectual framework, a set of expectations and explanations widely agreed upon by scientists, such as the Ptolemaic view of astronomy (that included the belief that the Earth was at the centre of the universe) before the Copernican revolution (which overturned this view and replaced it with a heliocentric one); or Newtonian physics as it was until Albert Einstein came on the scene.
Normal science is described in textbooks. Scientists learn about the paradigm, and the experiments that support it, and are taught how to be problem-solving contributors to this larger project. They aren’t seeking novel grand theories, but rather are trying to make sense of particularities within the dominant paradigm.
Gradually, anomalies emerge, observations that don’t fit the paradigm. Some scientists are particularly perplexed by these and start to question the fundamental assumptions of the framework they have been working within. They dare to speculate about the validity of the paradigm itself, eventually proposing a new one. A phase of scientific revolution ensues.
One of Kuhn’s observations is that when these crisis points occur there isn’t necessarily sufficient evidence to overturn the existing paradigm. That’s partly because the way scientists at that point understand the world is so much coloured by the framework they use.
The new paradigm suggests new experiments, new places to look for corroboration. The two paradigms compete for dominance, and then normal science can begin again in earnest once the new one is established.
These revolutions in scientific thought have occurred throughout the history of science, and many will see them as progress. On a commonsense view of science these revolutions give us better approximations of what the world is really like, what’s truly out there.
That’s not how Kuhn saw things though. His approach was more controversial.
After the scientific revolution, according to him, scientists see the world differently, so differently that there is a sense in which it is a different world, or as one Kuhn-inspired bumper sticker puts it, “shift happens”.
The most controversial aspect of Kuhn’s thought was that he claimed incommensurability between different paradigms. What many took this to mean was that there was no way of judging that one paradigm was better than another.
Progress only makes sense within the normal phases of science when problems with a framework can be solved. According to Kuhn, there is no easy way to see if a new paradigm is any better at describing reality than the old one.
That seemed to lead to relativism, the idea that different interpretations of reality are of equal worth. Kuhn denied this in later publications, but philosophers of science are still disputing exactly what he did mean.
There is a strange postscript to all this. Kuhn inadvertently launched the career of the documentary film-maker Errol Morris. Morris was a doctoral student of Kuhn’s at Princeton. He challenged Kuhn’s apparent relativism relentlessly, and, according to Morris, Kuhn got so worked up one day that he threw a cut-glass ashtray full of cigarette butts at his student. It missed.
Morris had to leave, and later quit philosophy. But he got his revenge many years afterwards by publishing a diatribe against Kuhn (or as most critics believe, against a caricatured version of his thought) called, of course, The Ashtray.
