Thomas Kuhn and the Structure of Paradigms

Thomas Kuhn wrote The Structure of Scientific Revolutions in 1962. Perhaps no other volume has had as much of an impact on philosophy of science and on how scientists themselves perceive their work. Even the terms “paradigm” and “paradigm shift” have become common currency as a result of Kuhn’s work and the debates surrounding it.

Yet, Kuhn’s work is often misunderstood, or, worse, employed to support this or that pet project. Supposedly “intellectual” creationists have employed Kuhn to claim that science isn’t really accomplishing anything or that science’s results can never be taken seriously. In so doing, they neglect the subtleties of what Kuhn really argued, and they paint with much broader strokes than Kuhn himself intended.

First, Kuhn is not saying that science doesn’t accomplish anything! Such a claim would be outlandish because, as just one example, medical advances have accomplished a great deal in both improving and lengthening human life.

Second, Kuhn is not saying that science’s results cannot be taken seriously! Such a claim would also be outlandish, because science’s results have countless practical applications, such as microwave ovens and probes landing on Mars and even a speeding comet. Science does indeed “work,” and so it is patently ridiculous to assert that it doesn’t have meaningful and very practical results.

No, Kuhn’s point in this regard is more subtle, and it is one that I have been trying to emphasize throughout our lectures and online materials so far: Science “works” but it is not a metaphysical truth-seeking mechanism. Its models (theories and paradigms) do make more or less accurate predictions about how things will appear to us to work in a given time slice. And we can use such models to do some increasingly amazing engineering! But “what works” and “what is true” are not the same sort of evaluation. And what Kuhn notes is that the metaphysical entities claimed by various scientific models are the things we cannot put much stock in. Engineering is not the same enterprise as metaphysics.

Science is at its best when employed toward the former, and it is at its worst when employed toward the latter. And scientists are at their worst when they conflate the two.


Normal Science

Kuhn’s approach to interpreting the history of science rests upon a phrase he uses throughout: “normal science.” He defines it this way: “In this essay, ‘normal science’ means research firmly based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice” (p. 10). So, “normal science” is an adverb/verb phrase. It refers to a practice. The practice is that of research taking place within in a certain context. And that context, as we shall discover, is research done within a prevailing paradigm.



A paradigm provides the context and motivation in which normal science proceeds. But what is a paradigm? On page 10, Kuhn says: “Their achievement [the world views of Aristotle, Newton, etc.] was sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity. Simultaneously, it was sufficiently open-ended to leave all sorts of problems for the redefined group of practitioners to resolve. Achievements that share these two characteristics I shall henceforth refer to as ‘paradigms,’ a term that relates closely to ‘normal science.'”

So, a paradigm is defined by two features:

* It is enough of a break with past perspectives that it attracts a significant group of “practitioners” (researchers) to work within it.

* It not only solves a whole range of previously-perceived problems, but it also provides a rich field within which the researchers can explore for answers to a wide range of problems revealed by the new perspective.

So, paradigms provide a “view” of reality within which “normal science” takes place. And researchers are both educated and grounded in the prevailing paradigm before they are “turned loose” by the scientific community to work in a professional capacity. Thus, paradigms have staying power and profound psychological force, as they in fact define whole communities of research and researchers. Peer pressure is an immensely powerful force, and “normal science” is a peer-reviewed, peer-pressured context within which research takes place. As Kuhn says on page 11: “Acquisition of a paradigm and of the more esoteric type of research it permits is a sign of maturity in the development of any given scientific field.”

Paradigms serve research programs in two fundamental ways: 1) they contextualize research by defining what questions are worth pursuing; 2) they define not only the sorts of experiments that could in principle answer the worth-asking questions but thereby also define the experimental apparatus that will be developed with which to perform the experiments. Kuhn offers countless examples.

So, normal science in any given field is always constrained and defined by the paradigm(s) in which is functions. Thus, scientific research always has a “direction” and “intention.” It is never just random guessing that “just happens” to stumble upon some amazing, unforeseen set of truths. Random discoveries do occur, but these are not “normal science.” Thus, science seems to scientists to be “progressing,” because the whole history of science appears to be a matter of “refining” old views into new (and presumably more accurate) views; we are getting closer and closer to “the truth.” This perception of progress toward an “ultimate truth” is what motivates such books as Dreams of a Final Theory, by Nobel prize-winning physicist Steven Weinberg.


Evolutionary Theory as a Paradigm

Evolutionary theory is even beyond a Kuhnian paradigm at this point. Not only does it have the two earmarks of any normal paradigm, but it has achieved the status of a sort of meta-paradigm that contextualizes and informs a whole spectrum of scientific research across a wide range of disparate scientific fields. “Evolution” pulls them all together into one big basket! The term “evolution” now gets applied to all sorts of “unrelated” things, such as from star and galaxy formation to such things as plate tectonics and the appearance of ethical altruism. It seems now that every detail of what we perceive can be accounted for in terms of evolutionary theory. And this is because “evolution” is the catch-phrase for the entire naturalistic/materialistic world-view that almost entirely permeates contemporary science. So, now naturalism/materialism is encapsulated and accounted for in evolutionary terms. Moving away from the “evolutionary” paradigm at this point would mean fundamentally abandoning naturalism/materialism as an adequate account of nature.


Paradigm Shifts

In what has become now an almost pop-culture phrase, Kuhn captures the notion of a “scientific revolution” and defines how such “revolutions work. Kuhn writes on page 92:

What are scientific revolutions, and what is their function in scientific development? Much of the answer to these questions has been anticipated in earlier sections. In particular, the preceding discussion has indicated that scientific revolutions are here taken to be non-cumulative developmental episodes in which an older paradigm is replaced in whole or in part by an incompatible new one.

And by “incompatible,” Kuhn means “incommensurable,” by which he means that the two paradigms cannot even effectively communicate with each other! The terms they employ refer to entirely different metaphysical entities, such that they may appear to be “speaking the same language,” but in fact the “words” do not refer to the same things. A classic example is the displacement of Newton’s physics with Einstein’s. What Newton meant by a term like “force” is not what Einstein meant by the same term. The projected metaphysical entities of the two paradigms are “incompatible.” So, yes, we still “use” Newton’s equations for their practical effects, such as to land a probe on Mars. At velocities significant under light speed, Newton “works” just fine. But nobody believes in the metaphysical existence of Newtonian “forces” anymore. For example, Newton thought of gravity as an innate (and occult) attraction between material bodies, while Einstein explains gravity as an actual curvature of space-time. These are vastly different and entirely incompatible metaphysical accounts of observed phenomena!

Again, please note the vast gulf between “what works” and metaphysical truth. (Please carefully read what Kuhn says about Newton and Einstein on pages 98 through 100!) And Kuhn notes this very distinction between theoretical usefulness and metaphysical truth:

Scientific revolutions, as we noted at the end of Section V, need seem revolutionary only to those whose paradigms are affected by them. To outsiders they may, like the Balkan revolutions of the early twentieth century, seem normal parts of the developmental process. Astronomers, for example, could accept X-rays as a mere addition to knowledge, for their paradigms were unaffected by the existence of the new radiation. But for men like Kelvin, Crookes, and Roentgen, whose research dealt with radiation theory or with cathode ray tubes, the emergence of X-rays necessarily violated one paradigm as it created another. That is why those rays could be discovered only through something’s first going wrong with normal research. (p. 93)

So, men like Kelvin did not previously accept something like X-rays as part of their metaphysics. Their paradigm had no room for such a “ray” and did not predict its “existence.” When its “existence” (speaking in metaphysical terms) was “discovered,” that “discovery” necessarily threatened the metaphysics of the existing paradigm. And when a new “discovery” cannot be “integrated” into an existing paradigm, it can act as a catalyst to throw the prevailing paradigm into crisis. And “crisis” is what motivates paradigm shifts… the abandonment of one paradigm for another.

Kuhn goes into quite some detail about the factors that motivate paradigm shifts. We cannot here recount all of his research and argumentation. However, we can note a couple of key features that will concern us going forward:

1) When any individual is evaluating a particular paradigm, he/she exists within some community holding to this or that “prevailing” paradigm. Thus, as Kuhn puts it: “… the choice is not and cannot be determined merely by the evaluative procedures characteristic of normal science, for these depend in part upon a particular paradigm, and that paradigm is at issue. When paradigms enter, as they must, into a debate about paradigm choice, their role is necessarily circular. Each group uses its own paradigm to argue in that paradigm’s defense.” (p. 94)

2) The more sweeping and “prevailing” a particular paradigm is, the deeper must be the nature of the crisis that could motivate abandoning it. Mere “anomalies” can be interpreted as grist for further research projects, with the presumption that such research will “ultimately resolve the problems” without abandoning the paradigm. And it is always perceived as a legitimate argument to state: “Just because we have not yet solved the problem does not mean that we won’t solve it tomorrow.”

3) The very notion of “scientific progress” is self-referentially defined. Kuhn writes on pages 166 and 167:

In its normal state, then, a scientific community is an immensely efficient instrument for solving the problems or puzzles that its own paradigms define. Furthermore, the result of solving those problems must inevitably be progress…. Revolutions close with a total victory for one of the two opposing camps. Will that group ever say that the result of its victory has been something less than progress?… When it repudiates a past paradigm, a scientific community simultaneously renounces, as a fit subject for professional scrutiny, most of the books and articles in which that paradigm had been embodied…. In short, he [a student within a prevailing paradigm] comes to see it [the prevailing paradigm] as progress. No alternative is available to him while he remains in the field.

Thus, what science is by definition is “progress.” Science, thus, progresses simply because it engages in paradigm shifts! This point cannot be overemphasized!

4) But this “progress” is not toward anything like metaphysical truth, as Kuhn writes on page 170:

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…. The developmental process described in this essay has been a process of evolution from primitive beginnings–a process whose successive stages are characterized by an increasingly detailed and refined understanding of nature. But nothing that has been or will be said makes it a process of evolution toward anything. (emphasis in the original)

So, Kuhn is often (and accurately) summarized to be arguing: “Science continually progresses… but not toward anything.”



Evolutionary theory today is indeed a sort of meta-paradigm that informs and directs the research programs across the body of science. As it has become more ponderous, prevailing, and pervasive, it becomes harder and harder to threaten by what is actually an ever-increasing body of countervailing evidence. Evolution explains everything, and all “progress” in science is defined in its terms. Thus, the whole of scientific metaphysics comes to rest on the shoulders of evolutionary theory, because all observed phenomena simply must in some way boil down to the “evolution” of galaxies, perhaps whole universes, and ultimately to such personal phenomena as ethics and consciousness itself. “Evolutionary theory,” writ large (as it is), just is naturalism/materialism, and that entire meta-paradigm cannot be “evaluated” from within by its own practitioners.

Yet, in order to effectively analyze the paradigm, we must in charity “get into” it enough to talk its talk and truly see its interpretive mechanisms and motivations. Ultimately, the only way to cause the profound and sweeping paradigm shift that religionists believe must take place is to demonstrate the vast superiority of the religionists’ alternative paradigm in the necessary function of research programs and puzzle-solving activities that constitute normal science. Something like this is surely the implicit motivation behind such movements as “creation science,” as such movements attempt to show how “real science” can take place within the non-naturalistic paradigm. However, just showing that an alternative exists (to the extent that such movements even can demonstrate that) is merely a necessary and not a sufficient condition for causing paradigm shift! To get paradigm-practitioners to seriously question their paradigm from within, it is critical to demonstrate that such profound anomalies exist in the paradigm that they rise to the status of full-blown crisis. This creation-scientists have so far entirely failed to do.

If Kuhn is correct about “the structure of scientific revolutions,” then the revolution creation-scientists are pushing for will depend upon them “getting into” the paradigm they seek to overthrow (which includes naturalism/materialism), and this they cannot do! So, the result is exactly what we do indeed see in the endless debates: Both sides talking past each other, even as they seem to be employing the same basic terminology. This is exactly what Kuhn would predict: incommensurable paradigms using the same words with entirely different meanings and contexts.

The actual debate is fundamentally philosophical. This is where the likes of Phillip Johnson have had the most influence, as he has led the way in recognizing that the prevailing paradigm of all science has become necessarily naturalistic/materialistic. Now, to make progress toward revolution, we must demonstrate those phenomena that cannot in principle be accounted for in the context of that paradigm. Evolution will only fall alongside naturalism/materialism, and this fall will be philosophically motivated rather than in the context of a “scientific” debate about “scientific” evidence.