Thomas Kuhn, Paradigm Shifts, and Academic Rifts

Author: Michael Zerella
Category: Philosophy of Science
Word Count: 1000

This essay will discuss the important role played by Thomas Kuhn’s characterization of the scientific method in prompting on-going tension between two prominent schools of thought in academia: realism and constructivism. There are many subtle variations on these two schools, but they can broadly be construed in the following way. On one side are those who are committed to the idea that there exists a physical reality independent of human perceptions, and that science is in the business of systematically uncovering that reality. We’ll call those folks “realists.” On the other side are those who feel that human activity, specifically our psychology and sociology, shapes our reality. We’ll call those folks “constructivists” because they feel that, to a large degree, humans construct their reality. The realists are inheritors of a tradition that includes most of natural philosophy and the sciences. Constructivism, on the other hand, mainly arose in the 20th century and is more closely associated with realms in which it is already understood that psychological and social forces dominate. Such realms include literature, religion, politics, and folklore.

Before the rise of constructivism, science was almost universally assumed to be epistemically superior1 to all other fields of human inquiry. The idea was that scientists come up with theories that are then tested against nature itself, and if there is a mismatch between nature and theory, the theory is updated or replaced. Much of the history of epistemology involved attempts explain science’s superiority by characterizing that important connection between hard evidence and scientific theories. A common approach was to start with strict logical reasoning that philosophers had already identified as reliable, and then show how scientific reasoning conforms to that strict logic. However, by the mid-20th century, it was becoming clear that the actual methods used by successful scientists could not be characterized in terms of straightforward logic (e.g. Duhem, 1954). Realizing this, Thomas Kuhn started his analysis of science by examining the actual, day-to-day practices of successful scientists rather than trying to fit the scientific method into some pre-determined logical framework. In 1962, Kuhn published his findings in what turned out to be one of the most influential books of the century, The Structure of Scientific Revolutions.

Kuhn found that, contrary to a common assumption among philosophers, scientists almost never directly test their theories, and tests to find a theory false (as famously recommended by Karl Popper) are especially rare. Instead, scientists usually work under the assumption that their theory is (at least roughly) true. In fact, scientists take more than their theory for granted. They also work within accepted methods of investigation, accepted standards of evidence, accepted methods of statistical analysis, and an accepted conceptual understanding of their subject matter. All of that (and more) constitute what Kuhn called the “paradigm” that structures and guides everything that happens in a field of science, from the initial formulation of research questions, to constructing relevant experiments, to explanations of observable phenomena. Without a paradigm, scientists would be unable to follow a consistent overall plan for what to do or how to do it, and their field of study would not achieve the kind of success we come to expect from a real scientific discipline.

Kuhn called the daily activity of scientists working under their paradigm “normal science,” which includes the working out of unanswered questions or unsolved problems within the paradigm. Kuhn also called it “puzzle solving” because we can think of the paradigm as a big jigsaw puzzle that has much of the border and main features in place, but still contains many incomplete areas that invite new research. Sometimes an experiment may produce negative or unexpected results, but since the paradigm is assumed to be true, they attributed to experimenter error rather than to any problem with the paradigm itself. When a negative result persists despite repeated efforts to eliminate it, the result is declared an anomaly and set aside, leaving the paradigm unchallenged.

Eventually, the anomalies will become numerous enough or significant enough to finally prompt a direct challenge to the paradigm, perhaps even prompting a shift to a new paradigm, and it was Kuhn’s account of how scientists shift to a new paradigm that sparked major controversy and contributed to the rift between realists and constructivists. Kuhn believed that when a paradigm is finally abandoned, scientists say goodbye not only to the equations and models from the old theory, but also to the accepted methods of investigation, standards of evidence, and everything else that was used to guide their thinking under the old paradigm. As a result, Kuhn’s account does not allow for any paradigm-neutral way of comparing two rival paradigms in order to say that the newly adopted paradigm is better than the old one or that the shift represents an overall scientific advance. Any method we are tempted to use to evaluate the quality of one paradigm may not be applicable in the other paradigm, and so the paradigms are (as Kuhn called them) incommensurable.

Since, according to Kuhn, paradigms are incommensurable, social forces are left to dominate the process, and the socially dominant members of the scientific community end up convincing everyone else to accept a new paradigm (or to stick with the old one). This robs science of its epistemic superiority over other fields because, if Kuhn is correct, scientific theories ultimately are shaped by social forces rather than by an objective nature. Kuhn’s work set the stage for constructivists to argue that science is not any better at uncovering facts about nature than are religion, politics, or folklore. Instead, they argue that what we accept as reality is determined, in large part, by social factors (e.g. Feyerabend, 1975; Latour and Woolgar, 1979).

Through the latter 20th century, realists struggled to re-establish the reliability of science in the face of constructivist arguments.2 Today, most philosophers of science believe that paradigm-neutral methods and standards of evidence are preserved despite changes in theories, though most philosophers also accept something like Kuhn’s account of normal science, including the existence of bias in favor of existing theories (e.g. Chalmers, 1990; Kitcher, 1995).


1In this context, to be epistemically superior means is to be better at developing an accurate understanding of the world.

2There have been many public repercussions of this academic dispute. For example, public debates over things like science education and climate change often include indirect reference to Kuhn’s notion of incommensurable paradigms and the parity of scientific nonscientific ways of understanding the world.


Chalmers, Alan Francis. Science and Its Fabrication, University of Minnesota Press, 1990.

Duhem, Pierre. The Aim and Structure of Physical Theory, translated by Philip Wiener, Princeton University Press, 1954.

Feyerabend, Paul. Against Method, London: Verso, 1975.

Kitcher, Philip. The Advancement of Science – Science without Legend, Objectivity without Illusions, Oxford University Press, 1995.

Kuhn, Thomas. The Structure of Scientific Revolutions, University of Chicago Press, 1962.

Latour, Bruno and Steve Woolgar. Laboratory Life: The Social Construction of Scientific Facts, Beverly Hills: Sage Publications, 1979.

Popper, Karl. Logik der Forschung, Vienna: Julius Springer Verlag, 1935.


Mike is a philosophy instructor at the University of Colorado, Boulder. Mike earned a bachelor’s degree in biology in 1993 and a master’s in biology in 1995. He then taught high school science classes for several years before going back to grad school at the University of Colorado to earn his Ph.D. in philosophy in 2011. Unsurprisingly, he specializes in philosophy of science and philosophy of biology. Mike also enjoys the classic summertime Colorado activities like hiking, biking, camping, gardening, and going to bluegrass music festivals.