Thomas Kuhn

November 04, 2021

Thomas Kuhn (1922–1996) was an American historian and philosopher of science, best known for his 1962 book The Structure of Scientific Revolutions. In March 2020, I became interested in revolutions, which led me to read his book. I never finished that writing about revolutions, but I did finish the book, which I read carefully over a period of about six months.1

Even after months of attention and thought, I did not know the argument, in the sense of knowing I described yesterday. I felt there was more to learn.

To better grasp the argument, on 9 September 2020, I started tweeting every part of Kuhn’s argument. This was to teach myself more than it was to teach anyone else, but I am glad that people encouraged me to work in public.

76 days and 544 tweets later, I completed the thread. Since then I’ve been processing my own thread through spaced repetition in Readwise, as I described here.

In the book, Kuhn lays out a standard set of assumptions about how science works. Here’s how I’d summarize that view of science:

Science is an orderly endeavour, in which diverse theories are tested by decisive and repeatable experiments, leading to right theories being verified (or wrong theories being falsified). This “scientific method” produces a steady, gradual, and linear series of refinements of theory and precision, which leads to improved technologies and scientific progress.

For Kuhn, none of these things are true.


  • Scientific theories are not refined but completely overturned (in “scientific crises” which lead to changes of paradigm). These revolutions produce new unforeseen vistas and new types of progress. New theories are totally incompatible (“incommensurable”) with old theories. Scientists during crises are involved in a wild search for theories, which are often provided by outsiders to the field (including resorting to philosophy). Science essentially does not progress during these periods.
  • Science progresses rapidly during periods of “normal science” (i.e., not during crisis) not through a diversity of opinions but through consolidated consensus about how to apply a single paradigm. Scientists during this period solve well-defined puzzles. If you disagree with the paradigm, you are not a scientist. Outsiders and philosophers are excluded by specialist vocabulary and other tactics.
  • Progress in improving precision (articulating a given theory) is extremely rapid as long as this consensus persists. But when progress slows, consensus collapses, leading to to a new crisis.
  • There is no scientific method. Crisis science is a random search, and normal science is a period of intense puzzle solving. The attempted solutions are diverse, but the assumptions/central questions are not diverse. Rather than by unified method, science might be better defined as “that which progresses.”
  • Technology produces new sciences; science does not produce new technologies, except by accident or as a side effect.
  • Falsification faces the same problems as verification. Scientific theories cannot be falsified by facts, because there are no facts that are theory-independent.
  • Scientific theories cannot be tested against nature, but only against other theories, framing a specific subset of nature.
  • To put it more strongly, there is no “truth” towards which science steadily progresses. Instead, scientific investigation reveals what works in practice. To me it seems close to a pragmatic theory of truth; it is absolutely not a relativist position.
  • The central analogy of how science progresses is Darwin’s theory of evolution through variation and selection. It becomes “better” and more complex for a given scientific environment, but it does not progress “toward” anything, in the same way that evolution does not progress “toward” any fixed goal, but rather away from a simple beginning, to reflect a changing environment.

Where does the appearance of gradual progress come from, then? From rewriting the history of science in textbooks to make it look linear, thinks Kuhn.

I think that Kuhn’s theory possesses not only great explanatory power but also important consequences not just in the history of science, but for history itself. This applies to the history of civilizations as well as to each individual’s history (narrative identity). I’ll be updating this page as I go.


Because Kuhn remains central to my thinking and because I’ll be writing more about him soon, I’m starting this page as an index.

My work related to Kuhn:

  1. Technically I listened to the audiobook, which turned out to be slightly insane given how ornate his style is. I was constantly backing up the audio to listen again, and again, and again as I walked. I later read it digitally. I’m glad I did it both ways.

Bryan Kam

I'm Bryan Kam. I'm thinking about complexity and selfhood. Please sign up to my newsletter or see more here.