What’s the Support for Kuhn’s Incommensurability Thesis? A Response to Mizrahi and Patton, James A. Marcum

SERRC —  September 23, 2015 — 4 Comments

Author Information: James A. Marcum, Baylor University, James_Marcum@baylor.edu

Marcum, James A. “What’s the Support for Kuhn’s Incommensurability Thesis? A Response to Mizrahi and Patton.” Social Epistemology Review and Reply Collective 4, no. 9 (2015): 51-62.

The PDF of the article gives specific page numbers. Shortlink: http://wp.me/p1Bfg0-2iD

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Moti Mizrahi (2015) examines whether there are “good arguments” to support Kuhn’s taxonomic incommensurability (TI) thesis. He concludes that there is neither “valid deductive” nor “strong inductive” support for the thesis and that consequently TI should not be believed or accepted. In response, Lydia Patton (2015) claims that the most “influential” arguments within the history of science are abductive or inference to the best explanation (IBE) rather than deductive or inductive arguments.

A Role for Personal Experience

After reviewing and analyzing this exchange, I propose that although argumentation is important for supporting Kuhn’s TI thesis, it is not the only type of support—or possibly even the most persuasive. I contend that the historian’s personal or psychological experience of accessing a revolutionary change in science—as illustrated in Kuhn’s own experience of laboring to understand the Aristotelian idea of motion while assuming a Newtonian idea of motion—represents a compelling type of support for TI. To that end, I reconstruct briefly a case history from the biomedical sciences and discuss how it supports TI vis-à-vis the Mizrahi-Patton exchange.

Although Mizrahi distinguishes between taxonomic and methodological incommensurability theses, he limits his remarks to the TI thesis. He defines TI accordingly

Periods of scientific change (in particular, revolutionary change) that exhibit TI are scientific developments in which existing concepts are replaced with new concepts that are incompatible with the older concepts. The new concepts are incompatible with the old concepts in the following sense: two competing scientific theories are conceptually incompatible (or incommensurable) just in case they do not share the same “lexical taxonomy.” A lexical taxonomy contains the structures and vocabulary that are used to state a theory (2015, 362).

According to this definition, TI pertains principally to the conceptual incompatibility between two competing theories, which is related to their lexical taxonomies.[1] Although this definition seems adequate prima facie, questions arise about the different types of incompatibility and the relationship between incompatibility and incommensurability. For example, Eugene Lashchyk (1969) pointed out that besides conceptual incompatibility there is also logical incompatibility within Kuhn’s The Structure of Scientific Revolutions (Structure). Moreover, conceptual incompatibility involves concepts that are contradictory or opposed to one another, while incommensurability also pertains to concepts that share no common measure or do not intersect with one another conceptually. In other words, incompatibility refers to right or wrong concepts while incommensurability to non-overlapping concepts in which truth and falsity are relevant but not determinant of conceptual conflict or tension. Incompatibility then is not equivalent to incommensurability, as Mizrahi suggests in the above definition of TI. For Kuhn, “The normal-scientific tradition that emerges from a scientific revolution is not only incompatible but often actually incommensurable with that which has gone before” (1964, 102).

In other words, incommensurability includes more than just conceptual incompatibility. Additionally, Kuhn later divides incommensurability into global and local versions, with the former representing wholesale changes in the lexical taxonomy and the latter more constrained changes. Thus, what constitutes a general notion of incommensurability is not as simple as identifying it with incompatibility.

On Deductive Support

Mizrahi next considers Kuhn’s TI thesis and whether it can be supported either deductively or inductively. Deductive support, according to Mizrahi, would take the following logical form.

(TI1): If competing theories were taxonomically commensurable, then terms would still refer to the same things in new theories…

(TI2): Terms do not refer to the same things in new theories…


(TI3): Competing theories are taxonomically incommensurable (2015, 363).

He then states that for this argument to be “deductively valid” TI3 must follow from TI1 and TI2, or TI1 and TI2 must entail TI3. As constructed, this is a modus tollens argument or inference and it is valid. But, he takes issue with the truth of the premise TI1 and thereby the soundness of the argument.

The truth of TI1, according to Mizrahi, depends on satisfying the following two conditionals.

(C1) If kind terms t refer to X in T1 and to X in T2, then T1 and T2 are taxonomically commensurable.

(C2) If kind terms t refer to X in T1 and to Y in T2, then T1 and T2 are taxonomically incommensurable (2015, 364).

He believes that (C2) is “false” and provides the following example to support his belief.

(K1): In biological taxonomy, “kid” refers to a young goat, whereas in folk taxonomy, “kid” refers to a child.


(K2): Biological and folk taxonomies are taxonomically incommensurable (2015, 264).

Mizrahi claims that “(K2) seems false” since, although goat and child belong to different orders, they do belong to the same class. He argues that the argument is “invalid” since “true premises cannot lead to false conclusions.” And, so he rejects TI1 above and consequently deductive support for TI. However, this example is not as apposite, as Mizrahi presumes, since biological taxonomy and folk taxonomy are not competing scientific theories to explain the taxonomic relationship of living organisms. A better example would be two competing biological taxonomic theories (Atran 1998).

Finally, Mizrahi summarizes the argument concerning the lack of deductive support for TI as follows,

(1) Reference change [or discontinuity] is conclusive evidence for (TI) only if reference change [or discontinuity] entails incompatibility of conceptual content.

(2) Reference change [or discontinuity] does not entail incompatibility of conceptual content.


(3) It is not the case that reference change [or discontinuity] is conclusive evidence for (TI) (2015, 367).

This argument is certainly valid, i.e. “a only if b” is logically equivalent to “if not b then not a”. But it is different in logical form and content, especially in terms of premises, from the earlier modus tollens argument. For example, the above argument introduces the notion of conceptual incompatibility whereas the earlier one does not. Again, the problem of the meaning and relationship between incompatibility and incommensurability for assessing deductive support is an issue. Finally, Mizrahi acknowledges that soundness is critical for assessing deductive support (2015, 368). Only if the premises are true can deductive arguments, given their valid form, be sufficiently sound to support TI.

On Inductive Support

Mizrahi next examines the inductive support for Kuhn’s TI thesis. He formulates the argument for such support accordingly,

(TI4) Some episodes from the history of science exhibit taxonomic incommensurability (e.g., the Newtonian-Relativistic Mechanics episode, the phlogiston-oxygen episode).


(TI3) Scientific change (specifically, revolutionary change) is characterized by taxonomic incommensurability. (In other words, competing theories are taxonomically incommensurable.) (2015, 368).

Although Mizrahi acknowledges that Newtonian-Relativistic Mechanics episode appears to support TI, he claims that “it is a mistake to generalize from a few selected examples that competing theories in general are taxonomically incommensurable” (2015, 368). In other words, he believes that TI advocates “cherry-pick” examples to support it. And, he argues that these examples are insufficient to provide strong inductive support for TI.

To substantiate the conclusion that the history of science provides few, if any, examples to support inductively Kuhn’s TI thesis, Mizrahi reconstructs a (single!) historical example from the period of early modern physiology during which researchers labored to account for blood circulation from the right to the left side of heart and to determine whether the venous artery (or the pulmonary vein today) contains air or blood. He first focuses on the rejection of the Galenic interventricular pores, then on the discovery of the lesser or pulmonary circulation, and finally on the valves of the veins. “By the time William Harvey began his work on the circulation of the blood,” Mizrahi insists, “the problems, if not the rudiments of a solution, were already set for him by his predecessors” (2015, 369). He then takes up the notion of anastomoses between the arteries and veins and claims that Harvey was not looking for capillaries as understood today but rather he was “looking for the anastomoses as Galen’s theory required” (2015, 370).

For Mizrahi, the historical case study supports conceptual consistency or stability—and not conceptual incompatibility or incommensurability—from one generation of researchers to the next.

Contrary to (TI), then, the Anastomoses episode exhibits continuity in terms of the problems practitioners worked on, and supplementation in terms of old concepts that were abandoned for a while (e.g., anastomoses) but then rediscovered and added to the new theory, rather than discontinuity and replacement, as (TI) predicts (2015, 370).

He concludes that the case study represents not a counterexample of TI but what John Pollock calls a “rebutting defeater,” i.e. an example that reduces or even eliminates justification of a particular belief—in this case TI. Finally, Mizrahi summarizes his argument against strong inductive support for TI accordingly,

(1) There is a strong inductive argument for (TI) only if there are no rebutting defeaters against (TI).

(2) There are rebutting defeaters against (TI).


(3) It is not the case that there is a strong inductive argument for (TI) (2015, 371).

As for Mizrahi’s argument against deductive support for Kuhn’s TI thesis, so the above argument against inductive support is valid. However, does the anastomoses historical example support Mizrahi’s conclusion? Is it a “rebutting defeater” of the thesis? To address these questions requires a reconstruction of Galen’s circulatory theory and the role anastomoses, especially in terms of the Harveian critic Riolan, within it.

Reconstructing Galen’s Circulatory Theory

Galen divided blood flow into two systems (Aird 2011, Pasipoularides 2014, Siegel 1968). The first system contains the liver, where the blood and the natural spirit originate, and the veins through which blood is dispersed to nourish the body. The second system contains the heart, where the vital spirit is concocted, and the arteries through which blood is distributed to animate the body. According to Galen, the two systems are connected through interventricular pores between the right and left ventricles of the heart and through anastomoses between the veins and arteries of the body’s tissues. Although the two systems are connected, they did not represent a single structure for Galen. For Harvey, the two systems constituted a single structure and the connection between them was not Galen’s interventricular pores of the heart or vein-artery anastomoses of the tissues but rather pores (“porosities”) in the tissues.

Harvey was certainly not the first person to reject the interventricular pores of the heart, although he added to the evidence for their rejection. But, why did he reject Galen’s anastomoses between veins and arteries?[2] Although Galen’s theory was that blood flows directionally from the liver to the tissues and from the heart to the tissues and not in a retrograde manner as “ebb and flow,” as traditionally ascribed to him later (Fleming 1955, Hall 1975), Harvey’s rejection was based on a “recession theory” of blood flow, as developed after Galen.[3] In a letter to Marquand Schlegel, he chastised those like Riolan who believe that blood flows “unceasingly” from veins to arteries and back again through anastomoses (Elkana and Goodfield 1968). Rather, for Harvey, blood flow emanates from the heart and flows through the arteries to the tissues and returns to the heart through the veins. And, retrograde flow is prohibited by the values present in both the heart and veins. Finally, Harvey rejected Galen’s and Riolan’s anastomoses because he could not visualize them directly within tissues (Allchin 2005).

Does Harvey simply continue or supplement Galen’s (or Riolan’s) lexical taxonomy? Certainly Harvey is indebted to his predecessors for the problems surrounding blood flow (especially how blood gets from the right ventricle to the left ventricle, if there are no interventricular pores in the heart, or from the veins to the arteries, if there are no vein-artery anastomoses in the tissues). But, he does contribute significantly to the revolution that was unfolding in understanding blood flow—a shift from a Galenic paradigm to what would eventually be Harveian paradigm of blood circulation (Aird 2011, Schultz 2002).

First, Harvey posits a single system that consists of the heart, arteries, and veins—in contrast to Galen’s two systems (liver/veins and heart/arteries)—and in so doing he combines the two functions of blood—nutrition (venous blood) and animation (arterial blood) of the body—of the two systems into one system. Moreover, he shifts the “pores” from the interventricular septum between the right and left ventricles to the body’s tissues, and he eliminates the vein-artery anastomoses in the tissues and the associated recessive flow of blood, to justify a circular, unidirectional flow of blood (Harvey 1993, 44). As such, he redefines arteries and veins in contrast to Galen. For example, according to Harvey the veins emanate from the body’s tissues, not just the liver; they contain “worn-out” not “nutritive” blood; and they return the blood in toto and not simply a fraction of it to the heart (Harvey 1993, 47). Finally, Harvey introduces a robust justification for circular, unidirectional flow—in contrast to Galen’s non-circular, directional flow and to the theory of recession blood flow—by measuring cardiac output. According to Harvey, the amount of blood expelled from the heart in a given period exceeds that which the tissues can consume (Harvey 1993, 61-2). In sum, Harvey’s work on blood circulation is not normal but revolutionary science, in the Kuhnian sense (Quin 1997, Schultz 2002), in that terms and ideas between the two competing paradigms are non-overlapping and thereby taxonomically incommensurable.[4]

Patton’s Response

In response to Mizrahi, Patton claims that the lack of valid deductive and strong inductive support for Kuhn’s TI thesis does not defeat it, since historians and philosophers of science seldom, if ever, use these types of support for understanding and explaining the nature and progress of the natural sciences. Rather, she claims,

Many of the most influential arguments in the history and philosophy of science are second-order inferences about what we can conclude from the empirical success of science. They are explanatory hypotheses, or inferences to the best explanation, that cannot be construed as first-order inductive or deductive inferences (2015, 54).

In other words, historians and philosophers of sciences rely on abductive support to understand and explain science and its progress. To that end, Patton claims that Kuhn used the TI thesis to account for episodes in the history of science where paradigm shifts occur. As she concludes,

In the context of scientific revolutions, Kuhn does not argue from particular examples of scientific theory change to a general claim that every theory change involves incommensurability. Instead, he formulates explanatory hypotheses about those theory changes that are demonstrable cases of incommensurability: paradigm shifts (2015, 56).

Moreover, she diffuses Mizrahi’s anastomoses example claiming that it represents Kuhnian normal and not revolutionary science. Finally, although Patton defends Kuhn’s TI thesis she agrees with Mizrahi that meta-theorizing about science has become untethered from philosophical argument and asserts that if his “plan is to consign sweeping, inductive meta-narratives to the flames, I will bring the gasoline” (2015, 57).

In response to Patton, Mizrahi acknowledges the need for gasoline and is open to her thesis concerning abductive or IBE support for TI; but, he then asks her “how you think the IBE for TI is supposed to run? What is it that TI explains better than other competing hypotheses” (July 28, 2015; http://bit.ly/1NSXdn1)? Patton addresses Mizrahi’s first question, claiming that “paradigm shifts explain taxonomic incommensurability … TI is not the explanation, it’s the explanadum” (July 28, 2015; http://bit.ly/1MIzaHi). In other words, TI is what is explained (explanadum) and paradigm shifts do the explaining (explanans). Thus, an argument for TI might be stated as follows:

(1) If terms of competing theories are non-overlapping taxonomically and do not refer to the same thing, then the competing theories are TI.

(2) Terms of competing theories are non-overlapping taxonomically and do not refer to the same things.


(3) Competing theories are taxonomically incommensurable.

In other words, TI is the result of a paradigm shift or scientific revolution in which lexical entries are non-overlapping between two competing paradigms. Moreover, this argument is valid as a modus ponens inference, and sound, if the premises are true. To Mizrahi’s second question, she argues that TI, if it “exists at all, even in one case, it’s a counterexample to a competing explanation of the history: the cumulative account” (July 30, 2015; http://bit.ly/1MIzaHi). Finally, Patton concludes she is not insisting that

Kuhn is giving an IBE [for justifying TI], just that he could be. Or he could be giving an abductive argument, or a transcendental one, or a regressive argument … or he could be proposing a historical interpretation (July 30, 2015; http://bit.ly/1MIzaHi).

In other words, was Kuhn offering an argument for TI or simply a historical narrative? A question she considers “tricky and crucial” for supporting Kuhn’s TI thesis.

Indeed, whether Kuhn was offering an argument or a historical narrative for TI is a tricky but crucial question. In introducing Structure, Kuhn acknowledged that “some readers will already have wondered whether historical study can possibly effect the sort of conceptual transformation aimed at here” (1964, 8).[5] The problem as he envisioned it for the reader was that Kuhn was violating traditional “dichotomies”, especially the dichotomy of history simply as a descriptive discipline and philosophy as a logical one. But Kuhn did not accept this dichotomy. “History, if viewed as a repository for more than anecdote or chronology,” as he so famously penned, “could produce a decisive transformation in the image of science by which we are now possessed” (1964, 1). In other words, he was confident that history could provide the necessary support to defend the image of science he was proposing, which included the incommensurability thesis (IT).

Contexts of Discovery and Justification

Kuhn points out other dichotomies he was transgressing as well, particularly “the very influential contemporary distinction between ‘the context of discovery’ and ‘the context of justification’” (1964, 8-9). In his historical studies, Kuhn found this distinction and others to be “extraordinarily problematic” in the sense that “they now seem integral parts of a traditional set of substantive answers to the very questions upon which they have been deployed” (1964, 9). In other words, the discovery process cannot be eliminated from the analysis of scientific knowledge and progress and only confined to psychology, as logical positivists/empiricists did, but it must be included in explaining how scientists justify their theories. So, both discovery and justification go hand-in-hand for Kuhn to provide a robust image of science that reflects the practices and methods scientists employ to investigate and explain natural phenomena.

Just as the contexts of discovery and justification are seamless for scientists in the production of scientific knowledge and in scientific progress, so they can be seamless for historians and philosophers of science as well for analyzing and explaining scientific knowledge and progress. In other words, the context of discovery for Kuhn’s historical studies was intimately connected to justifying his image of science and the role IT played in it. No better example of this connection can be provided than the one Kuhn himself offers in terms of trying to understand the Aristotelian concept of motion given Kuhn’s assumptions of motion based on Newtonian mechanics. Once he read Aristotle in terms of the context in which Aristotle wrote Physics, the Aristotelian text made sense to Kuhn. This experience, is not just a psychological catharsis but also an important factor—if not equally as important as logical argument—in supporting Kuhn’s image of science and especially incommensurability’s role in it.

Certainly logical argument is critical for supporting Kuhn’s IT, but comprehensive support for the thesis should also include its discovery. Interestingly, Mizrahi uses the discovery-justification distinction to motivate an analysis of the evidential support for TI.[6] In other words, Mizrahi’s wants to know if there are “compelling epistemic reasons”, i.e. “good arguments”, for justifying TI (2015, 362). By relying on this distinction, he demotes the discovery process to an inferior status or simply ignores it in terms of evidentiary influence. For example, he criticizes Eric Oberheim and Paul Hoyningen-Huene’s use of discovery language to justify TI as a “fact”.[7] But, can the discovery experience or process be so easily dismissed as support for TI? To address that question, I reconstruct briefly a biomedical historical case study from my personal experience of breaking into an alternative understanding of the clotting factor thrombin.

The Question of Thrombin

During the late nineteenth and into the early part of the twentieth century, thrombin was thought to be an enzyme responsible for blood coagulation (Marcum 2013). The German physiologist Alexander Schmidt from Dorpat identified several properties of enzymes, which he claimed thrombin exhibited and thereby justified labelling it as an enzyme. The chief property was thrombin’s catalytic activity. In other words, small amounts of the clotting factor were sufficient to deposit a fibrin clot through hydrolytic cleavage of fibrinogen. The American physiologist William Howell from The Johns Hopkins University initially confirmed the enzymatic or catalytic nature of thrombin early in his career; but later, he claimed that thrombin functioned not as an enzyme but as a colloidal.

According to Howell, thrombin bound to fibrinogen—with a 1:1 stoichiometry—and formed a complex with it, which resulted in the complex’s precipitation as a blood clot. In these two competing theories of blood coagulation, thrombin—although it refers to a clotting factor—refers to two very different substances, which resulted in subsequent changes to other lexical taxonomic entries of the competing theories. For example, for Howell the mechanism of clot formation no longer involved hydrolytic cleavage of fibrinogen by enzymatic thrombin but rather precipitation of fibrinogen by colloidal thrombin. Moreover, for the enzymatic theory fibinopeptides are a by-product of fibrinogen’s cleavage, while for the colloidal theory they do not exist. Thus, the two clotting theories may be viewed as incommensurable in that the type of entities and their properties (and even their existence) within the two competing lexicons do not overlap with one another in terms of the mechanism of blood clot formation.[8]

When first reading Howell’s later work on thrombin and blood coagulation, I was perplexed about what he was claiming for thrombin’s activity in blood clot formation. After reading his initial work on blood clotting, I naturally assumed that he held to an enzymatic view of thrombin throughout his career, since I had no reason to believe otherwise and since that view is the contemporary one I was taught and that I brought to my reading of Howell’s later works. But, as I read more about colloidal chemistry in the early part of the twentieth century one day the scales fell from my eyes, as it were, and I understood as clearly as I could Howell’s notion of thrombin and its function not as a hydrolytic enzyme but as a precipitating colloid. This experience had a significant impact on how I then came to understand science, especially its practice and progress, in terms of discovering natural phenomena and justifying scientific knowledge. In some sense, my experience represents a conversion, like a religious one, to the role TI played in understanding the nature of science and the development of scientific knowledge.[9]

Meta-Theories in History and Philosophy of Science

One final issue raised in the Mizrahi-Patton exchange, which requires addressing before concluding, is the status of meta-theories in history and philosophy of science. Are they simply fodder for bon-fires? Or, can they serve some useful function(s)? Although meta-theories are a source of contention, as Mizrahi and Patton note, yet they seem to be part of our cognitive or epistemic constitution. For one, meta-theories can function as grand narratives by which we find or construct meaning about the world. For example, Kuhn’s meta-theory of normal and revolutionary science, which he called historical philosophy of science, played an important role in the historiographic revolution in science studies (Kuhn 2000).

One of the problems, however, is that meta-theories are often taken as the final word and become static and oppressive. But, Kuhn’s shift in his meta-theory later in his career serves as an example of how to avoid this problem. As Patton notes (July 24, 2015; http://bit.ly/1gFPpq7), Kuhn’s notion of incommensurability “shifted over his career”. Importantly, that shift reflects a change in his own meta-theory from a historical to an evolutionary philosophy of science (Marcum 2015). Meta-theories then that are oppressive and parade as ultimate answers to questions about the world should be set aglow, while those that remain dynamic and thereby assist us in adapting to a constantly changing or evolving world should be used to illuminate it.

In conclusion, support for Kuhn’s TI thesis is not as straightforward as simply providing deductive or inductive argumentation but rather it is quite problematic. A major part of the problem is that deductive support depends on the truth or falsity of the premises, which in turn depends on the historical record and especially its interpretation. As Mizrahi demonstrates, valid deductive arguments can be constructed to support TI; but, if a premise is judged to be false then the argument is unsound and thereby unsupportive.

A similar problem plagues inductive arguments in that judging whether a historical case study is a “rebutting defeater” of TI depends on the reconstruction and interpretation of the case study. This problem is exemplified in the anastomoses case study Mizrahi uses in an attempt to defeat the inductive support for Kuhn’s TI thesis. As I show, however, it is conceivable that the case study is not a defeater but provides support for the thesis. Moreover, Patton’s claim that Kuhn might be relying on abductive arguments or IBE seems to support TI; however, again, interpretation of historical case studies looms large in providing such support.[10] Finally, the experience of the historian and/or philosopher of science in accessing the world of competing theories plays just as an important role as deductive, inductive, or abductive arguments, in providing support for the TI thesis. Why else would Kuhn have emphasized the thesis’ discovery in supporting it? [11]


Aird, William C. “Discovery of the Cardiovascular System: From Galen to William Harvey.” Journal of Thrombosis and Haemostasis 9 s1 (2011): 118-29.

Allchin, Douglas. “William Harvey and Capillaries: Can You ‘Discover’ Circulation Without Connections Between Arteries & Veins?” American Biology Teacher 67 no. 1 (2005): 56-9.

Allchin, Douglas. “Why Respect for History–And Historical Error–Matters.” Science & Education 15 no. 1 (2006): 91-111.

Atran, Scott. “Folk Biology and the Anthropology of Science: Cognitive Universals and Cultural Particulars.” Behavioral and Brain Sciences 21 no. 4 (1998): 547-69.

Elkana, Yehuda and June Goodfield. “Harvey and the Problem of the ‘Capillaries’.” Isis 59 no. 1 (1968): 61-73.

Fleming, Donald. “Galen on the Motions of the Blood in the Heart and Lungs.” Isis 46 no. 1 (1955): 14-21.

Hall, Thomas S. “Euripus; or, the Ebb and Flow of the Blood.” Journal of the History of Biology 8 no. 2 (1975): 321-50.

Harvey, William. The Circulation of the Blood and Other Writings. K. Franklin, Trans. London: Dent, 1993.

Hoyningen-Huene, Paul, Eric Oberheim, and Hanne Andersen. “On Incommensurability.” Studies in History and Philosophy of Science Part A 27 no. 1 (1996): 131-41.

Kuhn, Thomas S. The Structure of Scientific Revolutions. Chicago: University of Chicago Press, 1964.

Lashchyk, Eugene M. Scientific Revolutions: A Philosophical Critique of the Theories of Science of Thomas Kuhn and Paul Feyerabend. Doctoral Dissertation, University of Pennsylvania, 1969.

Kuhn, Thomas S. The Road Since Structure. Chicago: University of Chicago Press, 2000.

Marcum, James A. Tampering with Nature: Empirical Methodology and Experimental Onto-Epistemology. New York: Nova Science Publishers, 2013.

Marcum, James A. Thomas Kuhn’s Revolutions: A Historical and an Evolutionary Philosophy of Science? London: Bloomsbury, 2015.

Mizrahi, Moti. “Kuhn’s Incommensurability Thesis: What’s the Argument?” Social Epistemology 29, no. 4 (2015): 361-378.

Mowry, Brian. “From Galen’s Theory to William Harvey’s Theory: A Case Study in the Rationality of Scientific Theory Change.” Studies in History and Philosophy of Science Part A 16 no. 1 (1985): 49-82.

Oberheim, Eric, and Paul Hoyningen-Huene. “The Incommensurability of Scientific Theories” In: The Stanford Encyclopedia Of Philosophy (Spring 2013 Edition), edited by Edward N. Zalta. http://plato.stanford.edu/archives/spr2013/entries/incommensurability/

Pasipoularides, Ares. “Galen, Father of Systematic Medicine. An Essay on the Evolution of Modern Medicine and Cardiology.” International Journal of Cardiology 172 no. 1 (2014): 47-58.

Patton, Lydia. “Incommensurability and the Bonfire of the Meta-Theories: Response to Mizrahi.” Social Epistemology Review and Reply Collective 4 no. 7 (2015): 51-58.

Prendergast, James S. “Galen’s View of the Vascular System in Relation to that of Harvey.” Proceedings of The Royal Society of Medicine 21 no. 12 (1928): 1839-47.

Quin, C.E. “The Ideas of Thomas Kuhn in Relation to Medical Advances in the Sixteenth and Seventeenth Centuries.” Journal of the Royal Society of Medicine 90 no. 4 (1997): 225-8.

Schultz, Stanley G. “William Harvey and the Circulation of the Blood: The Birth of a Scientific Revolution and Modern Physiology.” Physiology 17 no. 5 (2002): 175-80.

Siegel, Rudolph E. Galen’s System of Physiology And Medicine. Basel: Karger, 1968.

[1] A lexical taxonomy is a catalog of sorts, composed minimally of concepts and terms.

[2] Historians claim Harvey’s rejection of anastomoses signifies his rejection of the contemporary notion of capillaries and not presaging it, since the latter is identified with the former (Allchin 2006, Siegel 1968).

[3] The “ebb and flow” or recession theory of blood flow was based on a misinterpretation of Galen (Siegel 1968).

[4] Indeed, as one commentator notes, Galen’s “general view of the blood-system…made a conception of a circulation impossible for him” (Prendergast 1928, 1845). For a critique of Kuhn’s philosophy of science in terms of the Galen-Harvey case study, see Mowry (1985).

[5] The conceptual transformation is from a view of scientific progress as unceasingly cumulative to one in which periods of normal or cumulative progress are punctuated by revolutionary periods, with incommensurability serving to separate the normal periods.

[6] Patton too relies on the discovery-justification distinction to motivate her analysis of the evidential support for TI, but she does not dismiss it completely as evident from her consideration of Kuhn’s support of TI in terms of an abductive or some other argument and historical narrative.

[7] Interestingly, Oberheim and Hoyningen-Huene’s analysis of Kuhn’s discovery of incommensurability appears inconsistent with their analysis of Kuhn’s analysis of scientific discovery and progress.

Scientific progress, Kuhn argued, is not simply the continual discovery of new facts duly explained. Instead, revolutions change what counts as the facts in the first place. When reigning theories are replaced by incommensurable challengers, the purported facts are re-described according to new and incompatible theoretical principles. The main goal of Kuhn’s Structure was to challenge the idea of scientific progress as cumulative, according to which what is corrected or discarded in the course of scientific advance is that which was never really scientific in the first place, and Kuhn used incommensurability as the basis of his challenge (Oberheim and Hoyningen-Huene 2013). But, elsewhere they claim that Kuhn viewed the “similarity relations” between entities and their reference not as something “out there to be discovered; rather their status is between invention and discovery” (Hoyningen-Huene et al 1996, 136).

[8] In other words, thrombin refers to a clotting factor in both competing theories but how it functions differs drastically.

[9] Obviously, such dramatic conversion is not mandatory for supporting TI.

[10] As noted earlier, Patton claimed that the anastomoses case study reflects normal and not revolutionary science.

[11] I thank James Collier for inviting me to respond to Mizrahi and Patton.

4 responses to What’s the Support for Kuhn’s Incommensurability Thesis? A Response to Mizrahi and Patton, James A. Marcum


    Dear James,

    Thank you so much for joining the conversation about my paper examining the arguments for TI.

    I’m afraid I’m not quite sure what you mean when you say that “comprehensive support for the thesis should also include its discovery.” As I say in my paper, the “discovery” language suggests that the thesis is true, given that one cannot discover what isn’t the case. But to assume that TI is true is to beg the question. Am I missing something here?

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  1. A Reply to Patton’s “Incommensurability and the Bonfire of the Meta-Theories”, Moti Mizrahi « Social Epistemology Review and Reply Collective - October 29, 2015

    […] James A. “What’s the Support for Kuhn’s Incommensurability Thesis? A Response to Mizrahi and Patton.&#8221… Social Epistemology Review and Reply Collective 4, no. 9 (2015): […]

  2. A Reply to James Marcum’s “What’s the Support for Kuhn’s Incommensurability Thesis?”, Moti Mizrahi « Social Epistemology Review and Reply Collective - November 11, 2015

    […] James A. “What’s the Support for Kuhn’s Incommensurability Thesis? A Response to Mizrahi and Patton.&#8221… Social Epistemology Review and Reply Collective 4, no. 9 (2015): […]

  3. The Role of Evidence in Judging Kuhn’s Model: On the Mizrahi, Patton, Marcum Exchange, Vasso Kindi « Social Epistemology Review and Reply Collective - November 16, 2015

    […] James A. “What’s the Support for Kuhn’s Incommensurability Thesis? A Response to Mizrahi and Patton.&#8221… Social Epistemology Review and Reply Collective 4, no. 9 (2015): […]

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