Executive Summary

Thomas Kuhn was a professor at Massachusetts Institute of Technology and author of The Structure of Scientific Revolutions, a classic in the history and philosophy of science. Kuhn challenges claims that science is or can be an objective process based upon observational facts that makes progress toward truth.

1. Kuhn uses paradigm to mean a scientific theory, a set of connected propositions used to explain and predict. In times of normal science, the paradigm is accepted by the members of a scientific community and is largely uncontested. In times of revolutionary science, a new paradigm is proposed and gains converts.  
2. Science students learn normal-science paradigms essentially by parroting their professors and textbooks, not by a first-hand assessment of reality: “science students accept theories on the authority of teacher and text, not because of evidence. What alternative have they, or what competence?” (80).
3. When they become practicing scientists, they work strictly within a paradigm, typically working only on issues and seeing the world only as the paradigm specifies: “No part of the aim of normal science is to call forth new sorts of phenomena; indeed those that will not fit the box are often not seen at all. Nor do scientists normally try to invent new theories, and they are often intolerant of those invented by others” (24).
4. Even so, problems (“anomalies”) arise for a paradigm, and eventually someone proposes a competing paradigm. Yet paradigms are “incommensurable”: they define terms differently propose different explanatory principles and methods. Consequently, they create different, subjective realities: “the proponents of competing paradigms practice their trades in different worlds” (150).
5. Since the scientists are operating in different worlds and have different beliefs about proper method, “The competition between paradigms is not the sort of battle that can be resolved by proofs” (148). Changes of scientific belief become like those in religion: matters of “faith” (158) and “conversion” (151).
6. We must therefore reject scientific “progress” as a subjective myth: “The answer to the problem of progress lies simply in the eye of the beholder” (163).
7. Further, “truth” is also suspect: “We may, to be more precise, have to relinquish the notion, explicit or implicit, that changes of paradigm carry scientists and those who learn from them closer and closer to the truth” (170).
8. Science’s “truths” are merely authoritarian power politics applied to the scientific community:  “Inevitably those remarks will suggest that the member of a mature scientific community is, like the typical character in Orwell’s 1984, the victim of a history rewritten by the powers that be. Furthermore, that suggestion is not altogether inappropriate” (167).

Source: Thomas Kuhn, The Structure of Scientific Revolutions, Second Edition, University of Chicago Press, 1962/1970. Executive Summary by Stephen Hicks, 2020.