Polleit, Thank You, Murray Rothbard, For Your Extreme “Defense of Extreme Apriorism”

— From Rothbard at 100: A Tribute and Assessment, Stephan Kinsella and Hans-Hermann Hoppe, eds. (Houston: Papinian Press and Property and Freedom Society, 2026) —

Thank You, Murray Rothbard, For Your Extreme “Defense of Extreme Apriorism”

Thorsten Polleit¹

 

1

Murray N. Rothbard (1926–1995) was a highly exceptional scholar. His contributions to economics, political philosophy, ethics, history, money and banking, libertarian and other fields testify to a most remarkable intellectual power. In this essay, a very special, central aspect of Rothbard’s entire work will be the focus: namely, the aprioristic scientific method on whose foundation Rothbard consistently and unwaveringly built and developed his scholarly works from the very beginning. More precisely: Rothbard bases his scholarly work on the logic of human action, praxeology, as his academic teacher Ludwig von Mises (1881–1973) had previously formulated and rationalized it;² Rothbard thus stands most resolutely in the tradition of the Austrian School of Economics as shaped by Ludwig von Mises.

Rothbard was a dedicated defender of praxeology. He not only engaged deeply with those criticizing it. Above all, he also specifically addressed and explored the question of the epistemological status of praxeology. Venturing into this “philosophical minefield” is not only extremely important but also indispensable. For engagement with, and clarification of, the epistemological status of the logic of human action brings clarity about how and what kind of knowledge can be gained in economics. It also helps to refute misguided criticism, expose misinterpretations, and prevent errors in decisions made on the basis of what is called “economic knowledge.”

What follows will review and rationalize Rothbard’s position on the logic of human action as the correct scientific method for economics. Such a presentation seems very insightful because Rothbard explicitly advocates an “extreme apriorism,” yet at the same time appears to distance himself from Mises’s own interpretation of praxeology, at least in linguistic terms. How and why Rothbard epistemologically interprets the logic of human action, and especially how it differs from Mises’s own exposition, will be examined below in some detail. In this context, the interpretation of Hans-Hermann Hoppe and the philosophers of the “Hamburg School” will also be reviewed. Let us begin with some fundamental insights into Mises’s praxeology.

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Ludwig von Mises had already argued in the 1930s that economics—as the most developed subfield of the doctrine of human action³—is not an empirical science, but that it can only be consistently conceptualized as an aprioristic science of human action, as praxeology. Mises built his magnum opus Nationalökonomie (1940)⁴ consistently on this epistemological position. At the center stands the proposition “Man acts.” The truth value of this proposition is independent of experience, it holds a priori: It is indisputably true, possesses universal validity; whoever denies it commits a logical contradiction, since by doing so he presupposes as valid what he seeks to deny, and thus says something false.⁵  Building on the apodictically true proposition “Man acts,” further true propositions can be gained through logical deductions (provided no intellectual error is made in the process).⁶ As Hoppe points out:

Essentially, economic analysis consists of: (1) an understanding of the categories of action and an understanding of the meaning of a change in values, costs, technological knowledge, etc.; (2) a description of a situation in which these categories assume concrete meaning, where definite people are identified as actors with definite objects specified as their means of action, with definite goals identified as values and definite things specified as costs; and (3) a deduction of the consequences that result from the performance of some specified action in this situation, or of the consequences that result for an actor if this situation is changed in a specified way. And this deduction must yield a priori-valid conclusions, provided there is no flaw in the very process of deduction and the situation and the change introduced into it being given, and a priori—valid conclusions about reality if the situation and situation-change, as described, can themselves be identified as real, because then their validity would ultimately go back to the indisputable validity of the categories of action.⁷

To start with, every action is goal-oriented—the attempt to deny the truth content of this proposition would itself be a goal-oriented action and thus a contradiction. Action requires the use of means (or goods). Means are necessarily scarce by conceptual necessity, so human action always takes place under scarcity. And it always requires the use of time. For timeless action cannot be conceived without contradiction: If action were timeless, the pursued goals would be achieved immediately and directly, and the actor could no longer act—but this is a contradiction and thus false. The idea of means and ends presupposes cause-and-effect (causality). In a world without causality (which is actually unimaginable for us), there would be no room for human reason and human thinking. Such a world would be chaos in which humans could not orient themselves.

And of course, action also requires the the possession of knowledge to guide one’s action and to select means and ends—knowledge of causally efficacious means of action, technological recipes, and other facts about the world. As Mises writes,

Action … is not simply behavior, but behavior begot by judgments of value, aiming at a definite end and guided by ideas concerning the suitability or unsuitability of definite means.⁸

The logic of human action further implies that the actor has a time preference: He values an earlier satisfaction of needs higher than a later one (ceteris paribus). The manifestation of time preference is the (original) interest rate. Time preference and (original) interest rate are always and everywhere positive, cannot disappear, cannot fall to zero. The law of diminishing marginal utility can also be rationalized with the logic of human action (it is not a psychological law of saturation): It states that the actor prefers a larger stock of goods to a smaller one; and that the marginal utility of an additional unit of goods decreases with increasing endowment of goods.

Or take the law of returns.⁹ It states: For the combination of complementary economic goods in production, there exists an optimal quantitative ratio. If one deviates from the optimal quantitative ratio by increasing the quantity of only one of the complementary goods, the yield either does not increase at all or does not increase to the extent that the expenditure grows. By having recognized the quantifiability of utility effect as a prerequisite for treating a good as an economic good, we have already implicitly stated from the perspective of human action logic that there must be an optimum for the combination of complementary goods.

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What epistemological status does praxeology have? Hoppe sees in the proposition “Man acts” a synthetic a priori judgment as formulated by the Königsberg philosopher Immanuel Kant (1724–1804): “(T)he proposition that humans act, fulfills the requirements precisely for a true synthetic a priori proposition.”¹⁰ Hoppe has also characterized Mises’s epistemological position as that of a Kantian: “The characteristic mark of Kantian philosophy is the claim that true a priori synthetic propositions exist—and it is because Mises subscribes to this claim that he can be called a Kantian.”¹¹ This may require some more explanation.

According to Kant’s “Copernican turn in the mode of thinking,”¹² there are necessary conditions of the possibility of experience, and they can be traced back to the fact that man exercises his faculties of experience; this is what Kant deals with in his transcendental epistemology. Only what satisfies the conditions under which man can experience can be experienced by man, or rather, all objects of experience must satisfy the transcendental conditions of human experience. Kant formulates it as follows:

the conditions of the possibility of experience in general are at the same time the conditions of the possibility of the objects of experience, and thus have objective validity in a synthetic a priori judgment.”¹³

Simply put, there are necessary conditions of experience that arise from the exercise of man’s cognitive faculty.¹⁴ All objects of his experience must satisfy these conditions. Therefore, statements asserting that the objects of experience satisfy precisely these conditions are synthetic a priori judgments in the Kantian sense.

The categories of thought in the Kantian sense,¹⁵ as provided by the logic of human action—think here, for example, of goals, means, scarcity, causality, time preference, (original) interest rate, but also (in the psychological sense) value, cost, revenue, profit and loss—are, seen in this way, conditions of the possibility of man making objectifiable experiences in the economic sphere, in reality; they have validity in a synthetic a priori judgment. They are categories of thought that man imposes on the objects of his experience.

The philosophers Rolf W. Puster and Michael Oliva Córdoba¹⁶ argue that the propositions of Mises’s logic of action have cognitive value and are insightfully true independently of experience: “The propositions of praxeology are analytic (true); praxeology, properly understood, is analytic praxeology.”¹⁷ This so-called “Hamburg interpretation” sees itself closely connected to Mises’s own position. Puster rightly points out, with reference to Mises’s writings, that Mises himself always described the propositions of praxeology as aprioristic, but never as synthetic-aprioristic propositions. One may well speculate about the reasons: Presumably Mises saw no necessity to actually determine the epistemological status of praxeology, considering the designation of economics as an aprioristic science sufficient.

It is rather unlikely that Mises deliberately avoided discussion of this question to evade an unwelcome confrontation—that did not correspond to his scholarly integrity. Especially so as Mises’s statement at this point is rather pragmatic: “The questions whether the judgments of praxeology are to be called analytic or synthetic and whether or not its procedure is to be qualified as ‘merely’ tautological are of verbal interest only.”¹⁸

At the same time, Mises left no doubt about his position that the science of human action is an aprioristic science: “The science of human action … is in all its parts not empirical, but aprioristic science; it originates, like logic and mathematics, not from experience, it precedes it.”¹⁹ Or:

Aprioristic science is pure conceptual science; it can bring forth nothing other than tautologies and analytic judgments. All its propositions are derived purely logically from concepts and conceptual definitions; they give nothing that was not already contained in the presuppositions.²⁰

Although Mises was reserved in the epistemological interpretation of praxeology, as already mentioned,²¹ he nevertheless unmistakably refers to the works of Immanuel Kant, using his terminology—for example in the form of the “a priori” or the “categories” of human action. And a look at Mises’s writings allows the judgment that he understands indeed the propositions of praxeology on the one hand as “analytic judgments a priori”: Propositions that can be insightfully true independently of experience; the truth content of an analytic judgment (of the asserted state of affairs) is decided not by experience but by the application of elementary logical laws (such as the law of contradiction).

At the same time, however, Mises’s mode of expression also allows an interpretation of praxeological propositions as “synthetic judgments a priori”: In synthetic judgments, knowledge about the subject of the proposition is extended without experience. Or rather, synthetic a priori judgments (as Kant understands them) are conditions of the possibility of experience, traceable to the exercise of human cognitive faculty. To this end, Mises writes:

That the edifice of our concepts and propositions does not immediately give full knowledge of reality cannot be called a defect. These concepts and propositions are the tools of thought that open the way to knowledge of reality for us, not this knowledge itself.²²

4

Rothbard, who sees himself entirely on the ground of Misesian praxeology and advocates an “extreme apriorism,” not only took on the criticism of Mises’s praxeology. He also explicitly devoted himself to the question of the epistemological status of praxeology. Rothbard, who focuses on the proposition “Man acts” and calls it the “action axiom,” surprisingly offers a different interpretation than Mises: For Rothbard, who locates his epistemological position according to his own statement with Aristotle (384–322 B.C.) and Thomas Aquinas (1225–1274), the axiom of human action is to be classified as “empirical,” not as “a priori” (or neo-Kantian), because Rothbard interprets it as a “law of reality,” not as a “law of thought”:

Whether we consider the Action Axiom “a priori” or “empirical” depends on our ultimate philosophical position. Professor Mises, in the neo-Kantian tradition, considers this axiom a law of thought and therefore a categorical truth a priori to all experience. My own epistemological position rests on Aristotle and St. Thomas rather than Kant, and hence I would interpret the proposition differently. I would consider the axiom a law of reality rather than a law of thought, and hence “empirical” rather than “a priori.” ²³

However, Rothbard immediately clarifies in the following sentence that he assigns a different meaning to the adjective “empirical” than the one common today: “But it should be obvious that this type of “empiricism” is so out of step with modern empiricism that I may just as well continue to call it a priori for present purposes.”²⁴ This clarification does not actually contradict his self-described Aristotelian, neo-Thomistic epistemological position, although it may seem confusing at first glance.²⁵

Let us explain. Aristotle’s epistemology is closely linked to his realistic ontology and logic.²⁶ According to it, human knowledge starts from sensory perception and can grasp the real structure of things (reality)—though not immediately the Platonic ideas, but the forms (εἶδος) that are present in the concrete things themselves. Aristotle himself does not use the expressions “law of reality” and “law of thought,” but they are used in the later tradition (especially Scholasticism, Neo-Scholasticism, and Aristotle commentators). The laws of thought include the three classical laws of thought: (1) the law of identity (A = A, something is what it is), (2) the law of non-contradiction (¬(A ∧ ¬A), it cannot be the case that statement A is true and the case that statement A is not true), and (3) the law of excluded middle (A ∨ ¬A), there is no third between being and non-being (in the same respect).

Aristotle emphasizes: These principles are not mere laws of thought (psychological), but ontological principles—they apply primarily to being itself (reality) and therefore also to thinking that seeks to represent reality. The so-called “law of reality” is in this sense usually a colloquial or neo-scholastic designation for precisely this ontological validity: Reality itself is free of contradiction, identical with itself, and allows no third between being and non-being. The “law of thought” is then the logical flip side: Our thinking must follow these laws because reality is structured that way.

That said, for Aristotle, the law of thought and the law of reality ultimately coincide—thinking is true when it hits the structure of being. And it is precisely against this background that Rothbard uses the adjective “empirical” and not “a priori,” and apart from that arrives at the same interpretation as Mises: that the action axiom provides knowledge about reality; that it can be insightfully true independently of experience, precedes it; that it cannot be denied without causing a logical contradiction.

In Rothbard’s own words:

For (1) it is a law of reality that is not conceivably falsifiable, and yet is empirically meaningful and true; (2) it rests on universal inner experience, and not simply on external experience, that is, its evidence is reflective rather than physical; and (3) it is clearly a priori to complex historical events.²⁷

Praxeology—understood as the aprioristic scientific method in the field of human action—is the foundation and defining core of Rothbard’s entire intellectual work: Rothbard regarded praxeology (the deductive, aprioristic science of human action as Mises developed it especially in Human Action) as the indispensable methodological pillar of economics and the Austrian School of Economics. Rothbard wrote in his preface to Mises’s Theory and History to the effect: “Without praxeology no economics can be truly Austrian or truly sound”²⁸—a quote that shows how central and non-negotiable praxeology was for him in economic and social science. Important fields of application of praxeology for Rothbard are the following:

Methodological foundation. — His book Man, Economy, and State (1962) is consistently built on praxeological principles. Rothbard starts from Mises’s action axiom (“Man acts purposefully”) and deductively derives the entire economic theory from it, exactly as Mises did in Human Action. Rothbard makes it clear that praxeology is the only way to gain economic laws that are universally true, logically compelling, and immune to empirical falsification (in contrast to positivist mainstream economics). Following Mises, Rothbard leaves no doubt about the appropriateness of “methodological dualism,” that the scientific method in the doctrine of human action must be different from that in the natural sciences.

Defense and elaboration. — Rothbard defended praxeology in many essays against criticism. Just think of his responses to George J. Schuller.²⁹ Rothbard defended Mises (and praxeology) point by point. For instance, he rejected Schuller’s opinion that praxeologists used empirical “facts” to support axioms or core procedures—praxeology derives theorems deductively from the action axiom and a few corollaries (like scarcity and choice among alternatives); and Rothbard also dismissed Schuller’s demand for ultra-formal symbolic logic as unnecessary; praxeology uses natural language deduction, which is appropriate for economic reasoning. The profound epistemological engagement was probably quite beneficial for Rothbard in applying (extreme) apriorism beyond economics—to ethics, political philosophy, theory of the state, etc.

Demarcation from other Austrians. — While later Austrians (such as Friedrich August von Hayek (1899–1992) or Ludwig Lachmann (1906–1990)) explicitly distanced themselves from Misesian praxeology, Rothbard, preferring empirical or hermeneutic approaches, always remained an uncompromising Misesian.³⁰ In fact, praxeology is for Rothbard not just one intellectual tool among many that a social scientist or economist could choose and use at will or not. It is rather the indispensable starting point and logical framework for everything Rothbard wrote in economics, philosophy, history, and libertarian theory. Without it, the Rothbardian system as we know it, libertarianism, simply would not exist.

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But why, one may ask, does Rothbard advocate an “extreme apriorism” as in his essay “In Defense of Extreme Apriorism” (1957)?³¹ Critics like Fritz Machlup³² or T. W. Hutchison³³ accused Misesian praxeology of being “extremely aprioristic” because it starts from the proposition “Man acts” as an absolutely true, synthetic-aprioristic premise, derives economic laws purely logically-deductively from it, and considers neither premises nor conclusions necessary or even possible for empirical verification (testing). Rothbard takes up this reproach and says: Yes, exactly that is correct—praxeology is “extremely aprioristic,” and precisely that is its strength, not its weakness.

In his Preface to Theory and History, Rothbard precisely explains what epistemological position an “extreme apriorist” holds: The fundamental axioms and premises of economics are absolutely true. The theorems logically deduced from them are therefore also absolutely true. There is not only no need for empirical verifications of the premises or conclusions. Such theorems cannot even be empirically tested (even if one wanted to)—because they are aprioristic and therefore not falsifiable in the positivist sense.

While Mises himself did not use the term “extreme apriorism,” Rothbard made it a program: Praxeology is the only scientifically tenable method for the social sciences. For Rothbard, “extreme apriorism” was by no means a flaw, but rather the appropriate description, as it denotes the decisive advantage of praxeology: It guarantees apodictic certainty and protects against the errors and confusions of positivism, empiricism, falsificationism as they are widespread in mainstream economics, which Rothbard consequently regarded as pseudo-scientific.

Rothbard’s defense of an extreme apriorism, his demand for an extreme apriorism as the (only) correct scientific method in the science of human action, remains unrefuted to this day, although unfortunately it has not (yet) made an inroad into the scholarly discourse. Yet the truth claim of extreme apriorism does not depend on which epistemological status one ultimately assigns to praxeology, as long as there is agreement that its propositions are aprioristic, i.e., to be classified as true and universally valid independently of experience.

That Rothbard, in his epistemological clarification of the proposition “Man acts,” adopts an Aristotelian, neo-Thomistic position, thereby (at least in apparent wording) distancing himself from Mises’s own view as a “law of thought,” and thus also seems not to harmonize with Hoppe’s later interpretation, ultimately proves to be—whether intended or unintended—compatible and above all extremely effective: Rothbard makes unmistakably clear that the truth claim raised by praxeology for its propositions is, as it were, supported, actually confirmed, from all epistemological perspectives that can be taken seriously. This is a truly important, perhaps hitherto underestimated, contribution that Rothbard has made here. Therefore, one can conclude by saying: Thank you, Murray Rothbard, for your extreme “Defense of Extreme Apriorism”!

1. Dr. Thorsten Polleit is Honorary Professor for Economics at the University of Bayreuth and President of the Ludwig von Mises Institut Deutschland. [↩]
2. See especially Ludwig von Mises, Grundprobleme der Nationalökonomie, Untersuchungen über Verfahren, Aufgaben und Inhalt der Wirtschafts- und Gesellschaftslehre (Jena: Verlag von Gustav Fischer, 1933), translated as Epistemological Problems of Economics, 3d ed., George Reisman, trans. (Auburn, Ala.: Mises Institute, 2003). See in particular “Umfang und Bedeutung des Systems apriorischer Sätze,” ch. 1, Part B, pp. 22–33 (corresponding to Epistemological Problems of Economics, ch. 1, §I), and idem, Nationalökonomie. [↩]
3. Mises deals with history—”[t]he other branch of the sciences of human action” (Ludwig von Mises, The Ultimate Foundation of Economic Science: An Essay on Method (Princeton, N.J.: D. Van Nostrand Company, Inc. 1962), p. 43)—in idem, Theory and History: An Interpretation of Social and Economic Theory and Evolution (Auburn, Ala.: Mises Institute, 2007 [1957]). On other possible sciences of human action as alluded to by Mises, such as war and conflict, see Stephan Kinsella, “Extreme Praxeology,” StephanKinsella.com (Jan. 19, 2007); idem, “The Other Fields of Praxeology: War, Games, Voting… and Ethics?“, StephanKinsella.com (Aug. 5, 2006). And of course, although Mises in his economic work deals with “the theory of cooperation or economics,” Mises, The Ultimate Foundation of Economic Science, p. 42, his work, as well as that of Rothbard, inevitably deals with the economic consequences not only of cooperation but of hampered markets, that is, of violent intervention. See idem, Human Action: A Treatise on Economics, Scholar’s ed. (Auburn, Ala: Mises Institute, 1998), Part Six, “The Hampered Market Economy”; Murray N. Rothbard, Man, Economy, and State, with Power and Market, Scholars ed., 2d ed. (Auburn, Ala.: Mises Institute, 2009), ch. 12 (“The Economics of Violent Intervention in the Market“) of Man, Economy, and State, and the entirety of Power and Market. [↩]
4. Ludwig von Mises, Nationalökonomie: Theorie des Handelns und Wirtschaftens (Edition Union, Geneva; reprint Auburn, Ala.: Mises Institute, 1940). [↩]
5. On the a priori see Otfried Höffe, Immanuel Kant (München: C.H. Beck, 2014), and the English translation of an earlier version, idem, Immanuel Kant (State University of New York Press, 1994), §3.2 et pass.; The Cambridge Companion to Kant’s Critique of Pure Reason, Paul Guyer, ed. (Cambridge University Press, 2010), pp. 76, 358, et pass.; J. Everet Green, Kant’s Copernican Revolution: The Transcendental Horizon (Lanham, MD: University Press of America, 1997).  [↩]
6. Note: such apriorism does not imply infallibility, as is sometimes erroneously claimed by logical positivists and empiricists. See Barry Smith, In Defense of Extreme (Fallibilistic) Apriorism, J. Libertarian Stud. 12, no. 1 (Spriln 1996): 179–192. [↩]
7. Hans-Hermann Hoppe, A Theory of Socialism and Capitalism: Economics, Politics, and Ethics (Auburn, Ala.: Mises Institute, 2010), p. 142. [↩]
8. Mises, The Ultimate Foundation of Economic Science, p. 34 (emphasis added). See also Rothbard, Man, Economy, and State, with Power and Market, p. 11.; Frank A. Fetter, Economics—Vol. 1: Economic Principles (NY: The Century Co., 1915), p. 465; Jörg Guido Hülsmann, “Knowledge, Judgment, and the Use of Property,” Rev. Austrian Econ. 10, no. 1 (1997): 23–48, p. 44; Hans-Hermann Hoppe, “Foreword,” in Stephan Kinsella, Legal Foundations of a Free Society (Houston, Texas: Papinian Press, 2023), p. xv; Stephan Kinsella, “Law and Intellectual Property in a Stateless Society,” Part III.B, and Against Intellectual Property After Twenty Years: Looking Back and Looking Forward, Part IV.C, in Legal Foundations of a Free Society; idem, “The Problem with Intellectual Property,” in Handbook of the Philosophical Foundations of Business Ethics, 2nd ed., Marianne Thejls Ziegler and Christoph Lütge, eds., Robert McGee, section ed. (Springer, forthcoming 2026); idem, “Libertarian and Lockean Creationism: Creation As a Source of Wealth, not Property Rights; Hayek’s “Fund of Experience”; the Distinction Between Scarce Means and Knowledge as Guides to Action,” C4SIF.org (May 6, 2025). [↩]
9. See Rothbard, Man, Economy, and State, pp. 33–38; also Hans-Hermann Hoppe, Kritik der kausalwissenschaftlichen Sozialforschung: Untersuchungen zur Grundlegung von Soziologie und Ökonomie (Opladen: Westdeutscher Verlag, 1983), pp. 59–64. [↩]
10. Hans-Hermann Hoppe, Economic Science and the Austrian Method (Auburn, Ala.: Mises Institute, 1995), p. 22. [↩]
11. Ibid., pp. 7–48; esp. p. 18; also Hoppe, A Theory of Socialism and Capitalism, ch. 6, pp. 117–148; see in this context also Thorsten Polleit, “On Immanuel Kant’s 300th birthday: Kant’s Epistemology and Its Influence on Ludwig von Mises’s Praxeology,” Power & Market (April 22, 2024).  [↩]
12. Immanuel Kant, Immanuel Kant’s Critique of Pure Reason. In Commemoration of the Centenary of its First Publication F. Max Mueller, trans., 2nd revised ed. (New York: Macmillan, 1922), “Supplement II: Preface to the Second Edition, 1787,” p. 693. See also Ermanno Bencivenga, Kant’s Copernican Revolution (New York: Oxford University Press, 1987); Green, Kant’s Copernican Revolution; and Desmond Hogan, “Kant’s Copernican Turn and the Rationalist Tradition,” in The Cambridge Companion to Kant’s Critique of Pure Reason, pp. 21–51. Cambridge: Cambridge University Press, 2010; Höffe, Immanuel Kant [German], pp. 89–105; idem, Immanuel Kant [English], §3.2. [↩]
13. Immanuel Kant, Kritik der reinen Vernunft, Ingeborg Heidemann, ed. (Stuttgart, 1966), B 197. [↩]
14. See Holm Tetens, Kants “Kritik der reinen Vernunft”. Ein Systematischer Kommentar (Stuttgart, Reclams Universal-Bibliothek, 2006), pp. 35–36. [↩]
15. See, for example, Höffe, Immanuel Kant [German], pp. 89–105; idem, Immanuel Kant [English], §§3.2, 3.3, ch. 5, et pass.; The Cambridge Companion to Kant’s Critique of Pure Reason; Green, Kant’s Copernican Revolution.  [↩]
16. See Michael Oliva Córdoba, “Uneasiness and Scarcity: An Analytic Approach Towards Ludwig von Mises’s Praxeology,” Axiomathes 27, no. 1 (October 2017): 521–529, in which he gives an analytical reconstruction of Mises’s methodological apriorism. [↩]
17. Rolf W. Puster, Dualismen und ihre Hintergründe, Foreword to the German edition of Mises’s Theory and History, Theorie und Geschichte. Eine Interpretation sozialer und wirtschaftlicher Entwicklung (München: Akston, 2014), p. 23 (italics in original). [↩]
18. Mises, The Ultimate Foundation of Economic Science, p. 44. [↩]
19. Mises, Grundprobleme der Nationalökonomie, p. 12. [↩]
20. Mises, Nationalökonomie, p. 19 (my translation). [↩]
21. See, for instance, Mises, The Ultimate Foundation of Economic Science, pp. 14–21, where he discusses the a priori but does not ascribe it to a specific epistemological school of thought. [↩]
22. Ibid. (italics added).  [↩]
23. Murray N. Rothbard, Economic Controversies (Auburn, Ala: Mises Institute, 2011), p. 108. [↩]
24. Murray N. Rothbard, Economic Controversies (Auburn, Ala: Mises Institute, 2011), pp. 108–109. [↩]
25. It should be emphasized that, like Rothbard’s more Aristotelian approach, Mises’s epistemology is decidedly realistic and not idealistic as maintained by some critics such as Ayn Rand and Randians. This is made even clearer by Hoppe’s realistic extension of Mises’s epistemology. See Hoppe, Economic Science and the Austrian Method, pp. 20-21:

    Our mental categories have to be understood as ultimately grounded in categories of action. And as soon as this is recognized, all idealistic suggestions immediately disappear. Instead, an epistemology claiming the existence of true synthetic a priori propositions becomes a realistic epistemology. Since it is understood as ultimately grounded in categories of action, the gulf between the mental and the real, outside, physical world is bridged. As categories of action, they must be mental things as much as they are characteristics of reality: For it is through actions that the mind and reality make contact.

    … With his recognition of action as the bridge between the mind and the outside reality; he has found a solution to the Kantian problem of how true synthetic a priori propositions can be possible.

    See also p. 68 et seq. [↩]

26. See, for example, Richard Percival Phillips, Modern Thomistic Philosophy: An Explanation for Students, 2 vols. (London: Burns, Oates & Washbourne, 1934–35), esp. pp. 36 ff. [↩]
27. Rothbard, Economic Controversies, pp. 108–109. [↩]
28. Murray N. Rothbard, “Preface” [1985], Mises, Theory and History, p. xix. [↩]
29. See George J. Schuller, review of Mises’s Human Action, American Economic Review 40, no. 3 (June, 1950): 418–422; Murray N. Rothbard, “Mises’ ‘Human Action’: Comment,” American Economic Review 41, no. 1 (March, 1951):
    181–185); Schuller, “Mises’ ‘Human Action’: Rejoinder,” American Economic Review 41, no. 1 (March, 1951); Rothbard, “Praxeology: Reply to Mr. Schuller,” American Economic Review 41, no. 5 (Dec. 1951): 943–946 (reprinted in Rothbard, Economic Controversies); Schuller,  (pp. 185-190). See also Jeffrey M. Herbener, Hans-Hermann Hoppe, and Joseph T. Salerno, “Introduction” to the Scholar’s edition of Human Action p. xviii-xix, discussing this debate. [↩]
30. In a letter on May 15, 1983, to Terence Hutchison, Friedrich August von Hayek wrote literally:

    I had never accepted Mises’s a priorism. … 1936 was the time when I first saw my distinctive approach in full clarity—but at the time I felt … that I was merely at last able to say clearly what I had always believed—and to explain gently to Mises why I could not ACCEPT HIS A PRIORISM. Curiously enough. Mises, who was so sensitive to criticism from younger men, praised that article without seeming to be fully aware how much it was in conflict with his views.

    Quoted in Bruce Caldwell, “A Skirmish in the Popper Wars: Hutchison versus Caldwell on Hayek, Popper, Mises, and methodology,” Journal of Economic Methodology 16 no. 3 (2009): 315–324, p. 323–324. Or consider Hayek’s foreword to the new edition of Mises’s Erinnerungen (1978). There he wrote in 1977: “And it seems to me today also understandable from the character of the struggle he had to wage that he was driven to certain exaggerated claims, such as the a priori character of economic theory, which I could not follow.” (p. XVI)

    See also John Gray, Hayek on Liberty, 3rd ed. (London and New York: Routledge, 1998), pp. 17–18 (arguing that Hayek never accepted Mises’s pure praxeological method); Bruce Caldwell, Hayek’s Challenge: An Intellectual Biography of F. A. Hayek (Chicago & London: University of Chicago Press: 2009), pp. 323–324; F.A. Hayek,”Economics and Knowledge,” Economica (New Series) 4, no. 13 (February 1937): 33–54 (criticizing Mises’s apriorism); and Nobel Prize-Winning Economist Friedrich A. von Hayek, Interviewed by Earlene Craver, Axel Leijonhufvud, Leo Rosten, Jack High, James Buchanan, Robert Bork, Thomas Hazlett, Armen A. Alchian, Robert Chitester, Completed under the auspices of the Oral History program University of California, Los Angeles (1983), “Tape: Craver I, Side One Tape Date Unspecified, p. 19 (pdf p. 34) (“If you have these two alternatives, of course there’s no way of checking whether the theory is true or not. And that led me, already, to the understanding of what became Popper’s main systematic point: that the test of empirical science was that it could be refuted, and that any system which claimed that it was irrefutable was by definition not scientific. I was not a trained philosopher; I didn’t elaborate this. It was sufficient for me to have recognized this, but when I found this thing explicitly argued and justified in Popper, I just accepted the Popperian philosophy for spelling out what I had always felt. Ever since, I have been moving with Popper.”), available at Stephan Kinsella, “Hayek Oral History,” StephanKinsella.com (Oct. 13, 2009).  [↩]

31. Murray N. Rothbard, “In Defense of ‘Extreme Apriorism,'” in Economic Controversies (Mises Institute version; Mises Daily), originally published in the Southern Economic Journal (January 1957). For related work by Rothbard on apriorism and related issues such as scientism and empiricism, see Rothbard, “The Mantle of Science” and other chapters in Section One: Method, in Economic Controversies. See also Hans-Hermann Hoppe, “In Defense of Extreme Rationalism,” in The Great Fiction: Property, Economy, Society, and the Politics of Decline, Second Expanded Edition (Auburn, Ala.: Mises Institute, 2021), originally published as “In Defense of Extreme Rationalism: Thoughts on Donald McCloskey’s The Rhetoric of Economics.” Rev. Austrian Econ. 3, no. 1 (1989): 179–214. See also works by Machlup and Hutchison, referenced below; and Scott Scheall, “What is Extreme about Mises’ Extreme Apriorism?“, CHOPE [Center for the History of Political Economy at Duke University] Working Paper No. 2016-23 (August 2016).

    On epistemological dualism, see Mises, The Ultimate Foundation of Economic Science; idem, Epistemological Problems of Economics; and Hoppe, Economic Science and the Austrian Method.

    For more on Hoppe’s realistic, Misesian-based epistemology, see Hoppe, Economic Science and the Austrian Method, pp. 20–21, 68–70, et pass. and comments in the note above. On Mises’s realism, see Ludwig von Mises, “Epistemological Studies,” in Memoirs, Arlene Oost-Zinner, trans. (Auburn, Ala.: Mises Institute, 2009) (formerly Notes and Recollections); Mises’s dismissive remarks on Popper in The Ultimate Foundation of Economic Science, chap. 4, §8 and chap. 7, §4; idem, Theory and History, chap. 1, §3. See also Edward W. Younkins, “Menger, Mises, Rand, and Beyond,” J. Ayn Rand Stud. 6, no. 2 (Spring 2005): 337–74, p. 342 et pass. (also in Edward W. Younkins, ed., Philosophers of Capitalism: Menger, Mises, Rand, and Beyond (Lexington Books, 2005) ), and Heidi C. Morris, “Reason and Reality: The Logical Compatibility of Austrian Economics and Objectivism,” Rebirth of Reason (May 10, 2005). [↩]

32. Machlup, one could say, “distanced himself respectfully” from Mises’s praxeology. See for example Fritz Machlup, Methodology of Economic and Other Social Sciences (New York: Academic Press, 1978), see p. 142–143 or p. 295:

    The ambition for something “more positive,” which would assure true deductions from true assumptions rather than merely valid deductions from fundamental postulates, moved Wicksteed, as it had moved Senior, to oppose the construction of a simplified model in favour of a supposedly complete one. This ambition reached its extreme in Ludwig von Mises’s praxeology, the all-embracing theory of human action ….

    Or, as a response to T.W. Hutchinson’s criticism of “extreme apriorism,” p. 495: “I know very few ‘extreme apriorists’ (e.g. Professor von Mises).” [↩]

33. Essentially, Hutchinson argues that economic “postulates” must be empirically verifiable or falsifiable, not treated as self-evident axioms immune to experience. See T. W. Hutchison, The Significance and Basic Postulates of Economic Theory (London: Macmillan, 1938; pdf); idem,  “Professor Machlup on Verification in Economics,” Southern Economic Journal 22, no. 4 (1956): 476–483; idem, The Politics and Philosophy of Economics: Marxians, Keynesians, and Austrians (Oxford: Blackwell, 1981). [↩]