Karl Popper and Barry Smith on the Metaphysical Research Program of Austrian Realism and Carl Menger’s Economics.
An unpublished paper delivered at a conference on Austrian thought at the University of Texas (Arlington) in 2013. I don’t expect everyone or indeed anyone to read it right through – this is a way of getting the paper on line so I can send the link to interested people instead of attaching a word file to email.
Abstract.
Barry Smith located an Aristotelian or “Austrian realism” framework of ideas which underpinned Carl Menger’s economics. In Popper’s terms this framework is a “metaphysical research program”. The elements of the framework are replicated in the program that Popper elaborated in his long debate with the historicists, the positivists and the quantum physicists. Another parallel in the thinking of Popper and Smith is the theory of conjectural or fallibillistic knowledge. This paper argues that if Menger could have accessed a theory of that kind he might have advanced his program instead of turning to methodological issues after he wrote the first of several planned volumes of economic theory. Today, if the Aristotelian/Austrian/Popperian framework can be revived, the Austrian contribution to the mainline of economics will be better appreciated and economics may be more effectively integrated with sociology and all the disciplines of the humanities including law, politics, and cultural studies.
Introduction
This paper is one of the products of a program to explore the synergy of the ideas of Karl Popper and the Austrian economists, especially in relation to the policy agenda of classical liberalism. This involves unpacking the implications and applications of several “turns” that Popper pursued in epistemology and methodology.
The synergy is obscured by some obvious differences, notably between Popper’s interventionist tendencies in economic policy and the laissez faire of the Austrians, and between Popper’s theory of conjectural knowledge versus the foundationalistic apriorism that Rothbard and Hoppe took from von Mises. The first is not a matter of philosophy or methodology and the second was resolved when Smith demonstrated that fallibillistic apriorism (equivalent to Popper’s conjectural knowledge) is an adequate platform for Austrian economics, so there is no need for the foundationalist variety (Smith, 1996).
The paper is organised as follows: first a section on the Popperian “turns”, then a section comparing the essential elements of the Aristotelian/Austrian framework that Smith found in Menger’s economics with Popper’s program. Then a section on the problems that Menger encountered in “the Methodenstreit” with the suggestion that a theory of conjectural or fallibillistic knowledge would have enabled him to press on with his theoretical program.
The Popperian Turns
The six “turns” are (1) conjectural or hermeneutic (2) objective, (3) against conceptual analysis or essentialism, (4) social or “rules of the game”, (5) biological or evolutionary and (6) metaphysical. These aspects of Popper’s thinking are not generally appreciated and they are seldom brought to the attention of students in the mainstream of teaching and research.
The conjectural, hermeneutic or non-justificationist turn means that Popper rejected the traditional concern of the theory of knowledge with the justification of our theories (typically our beliefs) by reference to some authority or foundational source of knowledge. The objective turn depicts knowledge, especially scientific knowledge, as a human product, spelled out for public inspection and criticism.
On the “anti-essentialist turn”, he did not accept that it is helpful to pursue extended analysis of concepts to “explicate” them or make them more precise. Against “essentialism” and the quest for linguistic precision he favoured clarity of speech and writing as a means to an end in the discussion of substantive problems, that is, the problems that concern working economists. “Never let yourself be goaded into taking seriously, problems about words and their meanings. What must be taken seriously are questions of fact, and assertions about facts: theories and hypotheses; the problems they solve and the problems they raise.” (Popper, 1976, section 7).
The social turn means taking account of the social nature of science and the function of conventions or “rules of the game” in scientific practice. Kuhn and the sociologists of knowledge are generally given credit for drawing attention to the social factor in science, however Jarvie in The Republic of Science (2001) identified what he called the “social turn” in Popper’s earliest published work, for example in Sections 4, 5, 9, 10 and 11 in The Logic of Scientific Discovery. The social turn also appeared in the chapter on the sociology of knowledge in The Open Society and its Enemies, first published in 1945 and in the final sections of The Poverty of Historicism. Wittgenstein and his followers could have made a contribution in this field if they had adopted a critical approach to the theoretical and practical implications of important real-life games, rules and conventions. For example they could have examined the impact of Keynesian economic policy on the convention of balancing State budgets or the shift in the concept of democracy from limited government under the rule of law to majority rule, and the erosion of responsible government by the “vote-buying motive”.
Biological themes can be found in The Logic of Scientific Discovery (dating from the original Logik der Forschung in 1935). “We choose the theory which best holds its own in competition with other theories; the one which, by natural selection, proves itself the fittest to survive.” (Popper, 1959, 108). That was only a hint of Popper’s interest in the biological approach which he revealed in the 1960s when he delivered a series of papers that are collected in Objective Knowledge: An Evolutionary Approach. Popper’s “metaphysical turn” attracted little attention although it is the most striking difference between him and the positivists. For this paper the most significant of the turns are the first, to address the blockage in Carl Menger’s program, and the last, to explain how unexamined metaphysical frameworks create winners and losers among research programs.
Against the justification of beliefs. In traditional epistemology the central concern was (and remains) the justification of beliefs. Philosophers persist with attempts to justify beliefs by various strategies including inductive logic and many texts do not even mention that Popper provided an alternative program. This can be described as a full-blooded “conjectural turn”, to claim that even our best theories may be rendered problematic by new evidence, new criticisms and new theories. This dates from 1935 and it anticipated the “hermeneutic turn” in the mainstream when the work of Kuhn and the modern French theorists made much of the theory-dependence of observations.
Attempts to justify beliefs generate an infinite regress. The alternative to the quest for justified beliefs is to form tentative critical preferences for theories (or policies) on the basis of their capacity to solve their problems and stand up to various forms of criticism, including experimental and practical tests. Bartley developed some of the implications of Popper’s “non-authoritarian” theory of knowledge and his “non-justificationism”. (Bartley, 1962, 1964, 1983). Smith’s exposition of “extreme fallibillistic apriorism” is also a theory of conjectural objective knowledge (Smith, 1996).
Metaphysical research programs. The metaphysical turn is a striking difference between Popper and the logical positivists, whose signature idea was to render all talk of metaphysics strictly meaningless. Popper developed the theory of metaphysical research programs during the 1950s as he worked on The Postscript to The Logic of Scientific Discovery. It flows from the idea that we should look at the history of a subject, and its current status, in terms of its problem situations.
In science, problem situations are the result, as a rule, of three factors. One is the discovery of an inconsistency within the ruling theory. A second is the discovery of an inconsistency between theory and experiment – the experimental falsification of the theory. The third, and perhaps the most important one, is the relation between the theory and what may be called the “metaphysical research programme”.
By raising the problems of explanation which the theory is designed to solve, the metaphysical research programme makes it possible to judge the success of the theory as an explanation. On the other hand, the critical discussion of the theory and its results may lead to a change in the research programme (usually an unconscious change, as the programme is often held unconsciously, and taken for granted), or to its replacement by another programme. These programmes are only occasionally discussed as such: more often, they are implicit in the theories and in the attitudes and judgements of the scientists.
I call these research programmes “metaphysical” also because they result from general views of the structure of the world and, at the same time, from general views of the problem situation in physical cosmology. I call them “research programmes” because they incorporate, together with a view of what the most pressing problems are, a general idea of what a satisfactory solution of these problems would look like. (Popper, 1982, 161)
The idea of the program can be applied to Popper’s own work, to see it as the unpacking of the implications and applications of his key ideas to problems in many fields. This “programmatic” approach to research apparently anticipated both Kuhn’s “paradigm theory” and the methodology of scientific research programs. Leaving aside the question of priority, the decisive difference between Popper and the others is the critical approach. Criticism of the paradigm/hard core assumptions is not recommended by Kuhn and Lakatos but criticism is the lifeblood of Popper’s program and that applies to the metaphysical theories that constitute the MRP. So the most important function of Popper’s theory of MRPs is to invite and encourage criticism of framework assumptions and the critical comparison of the assumptions that animate rival programs.
Wong provided a striking and original example of Popperian program analysis in his critique of Samuelson’s demand theory and Birner explained the coherence and power of Hayek’s work by describing it as a program to pursue an evolving research agenda that he set from the beginning of his publishing career (Wong, 2006 and Birner, 1994).
The Aristotelian/Austrian Frameworks of Smith and Popper
Smith explored the philosophical roots of Carl Menger’s economics and he found a number of Aristotelian framework presuppositions which demarcated “Austrian realism” from German philosophy at the time (Smith 1990, 1995). The following account draws on Smith (1990), to spell out the “Austrian-Aristotelian” program and the extent of agreement with Popper’s program.
1. “The world exists, independently of our thinking and reasoning activities.” This coincides with Popper’s realism regarding the external world, and also mental entities, plus (in Smith’s words) “other sui generis dimensions, for example of law and culture”.
2. “There are in the world certain simple ‘essences’ or `natures’ or ‘elements’, as well as laws, structures or connections governing these, all of which are strictly universal.” Popper took a similar metaphysical view of the uniformity of the laws of nature which he depicted in his later work as “propensities”.
3. “Our experience of this world involves in every case both an individual and a general aspect.” Smith found both radical empiricism and essentialism in Menger and other Aristotelians such as Brentano. “Radical empiricism” here is simply an aspect of realism which does not imply the epistemology of empiricism (accumulation of sense impressions): it means that individual apples and atoms exist in addition to the universal laws that regulate their characteristics and behaviour. And Menger’s essentialism involved the search for causal laws, not protracted conceptual analysis which both Menger and Popper deplored (Menger, 1985, 37). Smith noted that Menger was concerned with a priori categories (‘essences’ or ‘natures’) which exist in reality and the task is to specify the structures and connections among such essences, for example between economic categories such as value, rent, profit, the division of labour and money.
Theoretical economics has the task of investigating the general nature and the general connection of economic phenomena, not of analyzing economic concepts and of drawing the logical conclusions resulting from this analysis. The phenomena, or certain aspects of them, and not their linguistic image, the concepts, are the object of theoretical research in the field of economy. (ibid, 37)
The theoretical scientist, then, has to learn to recognize the general recurring structures in the flux of reality. And theoretical understanding of a concrete phenomenon cannot be achieved via any mere inductive enumeration of cases. It is attained, rather, only by apprehending the phenomenon in question as a special case of a certain regularity. (ibid, 44.)
Menger’s “apprehensions” appear to be the functional equivalents of Popper’s conjectures which are the creative (but fallible) source of ideas.
4. “The general aspect of experience need be in no sense infallible (it reflects no special source of special knowledge), and may indeed be subject to just the same sorts of errors as is our knowledge of what is individual.” In a nutshell, knowledge of both particulars and universals is fallible and conjectural. Our perceptions, our intuitions and even widely accepted scientific knowledge can be wrong. This is the equivalent of Popper’s “conjectural turn”. Smith’s “fallibillistic apriorism” and Popper’s conjectural knowledge both stand against the strong form of apriorism that many people identify with Austrian economics.
5. “We can know, albeit under the conditions set out in 4, what the world is like, at least in its broad outlines, both via common sense and via scientific method….Taken together with 3, this aspect of the Aristotelian doctrine implies that we can know what the world is like both in its individual and in its general aspect, and our knowledge will likely manifest a progressive improvement, both in depth of penetration and in adequacy to the structures penetrated. “
6. “We can know what this world is like, at least in principle, from the detached perspective of an ideal scientific observer. Thus in the social sciences in particular there is no suggestion that only those who are in some sense part of a given culture or form of life can grasp this culture or form of life theoretically.”
5 and 6 are further statements of realism and our capacity to learn more about nature and the social world with no concession to radical subjectivism or cultural relativism. That is consistent with Popper’s critical rationalism and his concern with the growth of knowledge.
7. “The simple essences or natures pertaining to the various different segments or levels of reality constitute an alphabet of structural parts. These can be combined together in different ways, both statically and dynamically (according to co-existence and according to order of succession).” No Popperian locution comes to mind which replicates that proposition which translates into a fairly uncontroversial statement about the existence of various levels of structural organization in nature.
Smith added three more points to demarcate the ideas of “Austrian realism” from the kind of ideas that dominated in Germany which are found in the their most influential forms in the work of Hegel and Marx. 8. “The theory of value is to be built up exclusively on ‘subjective’ foundations, which is to say exclusively on the basis of the corresponding mental acts and states of human subjects. Thus value for Menger in stark contrast to Marx is to be accounted for exclusively in terms of the satisfaction of human needs and wants. Economic value, in particular, is seen as being derivative of the valuing acts of ultimate consumers.” 9.”There are no ‘social wholes’ or ‘social organisms’.” And 10. “There are no (graspable) laws of historical development.”
Popper argued in favour of the points 8, 9 and 10 in The Poverty of Historicism and The Open Society and its Enemies. Smith’s ten points add up to a position that is very close to Popper’s metaphysics, his ontology and his epistemology. Smith argued that Menger formed his position from the version of Aristotelian thought that was circulating in Austrian circles. Popper developed his position in his lifelong debate with historicists, positivists, inductivists, instrumentalists, subjectivists and determinists, and his critique of the conventional (Copenhagen) interpretation of quantum theory.
Smith went on to suggest that the implications of the ten point program “
“do have a certain metaphysical cutting power.” And indeed they do, ruling out historicism (theses 2, 6, 8, 9 and 10) and positivism (theses 3 and 5), and “constructivism” and hermeneutic relativism as well (theses 1 and 5).
How Popper and Smith Could Have Helped Menger
“The Methodenstreit”, the ill-tempered debate between Menger and Schmoller of the “younger German historical school” started with Menger’s book on the methods of the social sciences (1883). It continued with sporadic exchanges between other members of the rival schools after the principals retired from the contest.
The point of this case study is to suggest that Menger was stuck for want of a theory of fallible or conjectural knowledge. He had to account for the foundations of scientific knowledge in economics and he did not succeed, being forced to resort to such devices as “the rule of cognition” to make his case in the face of difficulties with empirical evidence as the foundation. With the epistemological innovations furnished by Smith and Popper, Menger could have pressed on with his research program, elaborating and extending his basic insights and appealing to the explanatory power of his theories rather than justification by any special method of investigation.
The outcome of the Methodenstreit was inconclusive because neither party considered that they had anything to learn from the other. The debate has been sometimes depicted as a conflict of “theory versus history” or perhaps “induction versus deduction” but Menger did not disparage history, he just insisted that historical studies need to be informed by principles of explanation in the form of universal laws and the general theories which he and the “Manchester free traders” considered to be the core of the discipline. He perceived that the lack of interest in his Principles on the part of the historical school was a problem of methods.
“In a word, the progress of science is blocked because erroneous methodological principles prevail…[supported by powerful schools]…clarification of methodological problems is the condition of further progress.” (Menger, 1985, 27)
Bostaph (1978) identified eight issues in the debate, ranging from the criteria for designating the various branches of the subject, through the role of theory in explaining events, to whether “necessary” or universal causal laws can be formulated and tested using empirical data. The central issue was the possibility of “causal realism” in economics, and the existence of universal general theories, which Schmoller and the historical school denied, insisting that laws of historical development might be found, if at all, by accumulating historical data.
In addition to the personal vitriol in the exchange there are two major reasons why that issue was not resolved ; first, Bostaph explained that the protagonists and most of the subsequent commentators did not fully understood the epistemological issues that were at stake (Milford and Birner are notable exceptions). Second, Menger himself did not have a solution to the central issue, namely the justification or the basis or the rationale for accepting and using the laws that he postulated.
“The conclusion that the differences between the position of the historicists and that of Menger were minor compared to the similarities seems wholly unsupported. The differences in epistemological beliefs were so great that the debate …was not resolved because the fundamental sources of the disagreement lay unidentified and (substantially) untreated by both factions. The epistemological points at issue are matters of crucial importance to anyone who attempts to be self-conscious about his own methodological choices…because an inappropriate choice can (potentially) lead to a lifetime of wasted effort.” ( Bostaph, 1978, 15)
In that paper Bostaph did not indicate what the more correct or helpful result of the debate might have been if the epistemological issues had been directly addressed. He considered that Menger did well to state his assumptions and prescriptions in such a thorough manner and to seek for a methodologically self-conscious economic theory.
“For these reasons alone, there is ample cause to be glad that Menger was drawn into a Methodenstreit and did publish his methodological and epistemological views. It is only to be regretted that his research work on these topics later in life has not been published.” (ibid, 15)
It is even more regrettable that Menger’s concern with methodology distracted him from completing the additional three volumes that were originally planned to follow Principles. Bostaph cited several sources in Hayek to suggest that this was the case. In a later paper, with the benefit of Smith’s account of the Aristotelian/Austrian realism that informed Menger, Bostaph was more specific about the core issue.
“Unfortunately, neither Menger nor Schmoller recognized [the conflict between Humean nominalism and Aristotelian/neoscholasticism] and so never debated the most fundamental issues that separated them – their strongly differing theories of concepts, or universals, and of causality.” (Bostaph, 1994, 460). Bostaph concluded that Menger pinned his hopes for establishing exact universal laws on a combination of abstraction and simplification to establish ‘typical’ economic phenomena and then to discover the connections between these phenomena. “An ‘exact’ or causal law was an absolute statement of necessity to which, Menger pointed out, exceptions were inconceivable because of ‘the laws of thinking’.” (ibid , 463)
That did not represent a satisfactory solution and Milford and Birner discussed Menger’s unresolved efforts to find a way forward. According to Milford “He [Menger] examined this epistemological position primarily with respect to two problems: the problem of concept formation and the problem of justifying strictly universal statements.” (Milford, 1990, 225). Menger did not accept what he called the “realistic-empirical orientation of theoretical research” whereby repeated observations lead to laws, as repeated sunrises may suggest a law regarding the daily appearance of the sun. He rejected that form of simple induction for reasons much the same as Hume’s famous critique “although strangely without quoting him.” (ibid, 227)
A process of abstraction from the observed phenomena is required to penetrate to the exact or strictly universal laws which lie behind experience. This calls for recourse to “the rule of cognition” which was never properly explained.
Exact research solves the second problem of the theoretical sciences: the determination of the typical relationships, the laws of phenomena…Exact science, accordingly, does not examine the regularities in the succession, etc., of real phenomena either. It examines, rather, how more complicated phenomena develop from the simplest…in their isolation from all other influences…[so with strictly typical elements, exact measure, and isolation from other factors ] on the basis of the rules of cognition characterized by us above [we] arrive at laws of phenomena which are not only absolute but according to our laws of thinking simply cannot be thought of in any other way but as absolute. (Menger, 1985, 61)
That left the issue unresolved, hanging on the question of the “rule of cognition”. Birner also examined how Menger ran into problems with the justification, verification or foundations for universal laws. “For Menger (and his contemporaries, with the possible exception of Whewell) the logical or epistemological problem of the relation between exact and empirical theory is a problem about the justification of knowledge: [how can knowledge] be given a foundation that is true beyond doubt?” (Birner, 1990, 250)
At this point Menger encountered the problem of induction, which he recognized as a serious matter.
Menger’s joint justificationist-inductivist theory of knowledge entails that abstraction is conceived of as a process rather than as the description of a set of hypotheses with particular properties, regardless of how they were arrived at. But Menger is not a naive inductivist. He is well aware of the logical problem that arises if one maintains that general, universally valid laws can be derived from a finite number of observation statements. (ibid, 250)
Menger turned to the construction of “pure” or idealised types as a way out of the dilemma but he never broke out of the inductivist framework and he was stuck on a fourfold predicament.
Exact laws are: (1) not a prior truths; (2) nor the result of conceptual analysis; (3) nor are they empirical; (4) and they can be and must be justified. Item 3 seems to be unproblematic in view of Menger’s idea that exact laws are laws of ideal phenomena. But..Menger thinks that (5) exact laws contribute to our understanding of the real world…Menger’s justificationism-cum-inductivism makes it impossible for him to solve the epistemological level problem while at the same time maintaining both his methodological distinctions and his realism. (ibid, 251-2).
There is a desperately simple resolution to Menger’s central dilemma when we have the benefit of Smith’s fallibillistic apriorism and Popper’s theory of conjectural knowledge. These eliminate the demand for justification (in its strong form), that is, for certain foundations of theoretical propositions or a surrogate for certainty in the form of a numerical probability or degree of confirmation. Such warrants have yet to be provided despite the efforts of the logical positivists and the logical empiricists who followed them. The alternative is to evaluate theories in terms of their capacity to solve problems, to illuminate economic events, to permit the further elaboration of explanatory theories, to formulate effective policies, etc.
If Menger had not felt obliged to shore up the foundations of his system with a solution to the problem of justification, if he had simply appealed to the power and coherence of his approach, he could have pressed on with the extra volumes that he planned to complete the series after Principles. While the Methodenstreit performed a function in laying bare some issues in epistemology it did not produce a solution and the unresolved issues distracted Menger from his great task of theoretical development. The tools required to solve the espistemological problem only became available some decades later with Popper (1935, 1959) and Smith (1996).
Conclusion
It is suggested that the Aristotelian/Austrian framework which animated Menger’s economics and was reinvented by Popper is a robust alternative to the positivism and empiricism that became dominant in the philosophy of science in the twentieth century. Some of the tenets of the Austrian economists, but not the framework, were taken up by the mainstream of the profession, but as positivism rose in the 1930s and significant differences emerged between the Austrians and others, these differences were resolved in favour of the mainstream by weight of numbers rather than arguments. The framework assumptions of rival research programs could not be addressed effectively under the ban on metaphysics imposed by the positivists.
Frameworks include epistemological and methodological theories as well as ontological and metaphysical assumptions. One of the functions of frameworks is to create winners and losers. In economics the winners in the positivist/empiricist framework include general equilibrium theory, the “measure and model” approach, Keynesian macroeconomics, econometrics, mathematical game theory and the general demand for mathematical rigor. These developments isolated economics from the social sciences and humanities at large, and even from the world “outside the window”. If the Aristotelian-Austrian-Popperian framework can be revived, some alternative programs will thrive, especially the Austrians and the political program of classical liberalism. More important, the framework will facilitate the re-integration of economics, sociology, and all the disciplines of the humanities including law, politics, and cultural. The theory of conjectural or fallibillistic knowledge is an important addition to the Aristotelian/Austrian framework.
References
Bartley, William Warren (1964): “Rationality Versus the Theory of Rationality”, in Bunge (ed.), (1964), pp. 3-31.
Bartley, William Warren (1984): The Retreat to Commitment, La Salle, Illinois, Open Court.
Bartley, William Warren (1976): “The Philosophy of Karl Popper, Part I Biology and Evolutionary Epistemology”, in Philosophia, Vol. 6 (3-4), pp. 463-494.
Birner, Jack (1990): “A Roundabout Solution to a Fundamental Problem in Menger’s Methodology of Economics”, in Caldwell, (ed.) (1990), pp. 241-262.
Birner, Jack (1994): “Introduction: Hayek’ Grand Research Programme”, in Birner and van Zijp, (eds.) (1994), pp. 1-23.
Birner, Jack and van Zijp, Rudy (eds.) (1994): Hayek, Co-ordination and Evolution: His Legacy in Philosophy, Politics, Economics and the History of Ideas. London, Routledge.
Boettke, Peter (ed.) (1994): The Elgar Companion to Austrian Economics. Cheltenham, Edward Elgar.
Bostaph, Samuel (1978): “The Methodological Debate Between Carl Menger and the German Historicists”, in Atlantic Economic Journal, Vol. VI (3), pp. 3-16.
Bostaph, Samuel (1994): “The Methodenstreit”, in Boettke, (ed.) (1994), pp. 459-464.
Bunge, Mario (ed.) (1964): Criticism and the Growth of Knowledge. New York, The Free Press of Glencoe.
Caldwell, Bruce (ed.) (1990: Carl Menger and his Legacy in Economics. London, Duke University Press.
Hahlweg, Kai and Hooker, Clifford Allen (eds.) (1989): Issues in Evolutionary Epistemology. State University of New York Press.
Hayek, Friedrich (1979): The Counter-Revolution of Science: Studies in the Abuse of Reason. Indianapolis, Liberty Fund Press.
Jarvie, Ian (2000): The Republic of Science: The Emergence of Popper’s Social View of Science 1935-1945. Amsterdam, Ripodi.
Kuhn, Thomas Samuel (1970). “Reflections on my Critics”, in Lakatos and Musgrave, (eds.) (1970), pp. 231-278.
Lakatos, Imre and Musgrave, Alan (1970): Criticism and the Growth of Knowledge. London, Cambridge University Press.
Menger, Carl, (1985): Investigations into the Method of the Social Sciences with Special Reference to Economics. New York, New York University Press.
Milford, Karl (1990): Menger’s Methodology”, in Caldwell, (ed.) (1990), pp. 215-240.
Popper, Karl Raimund (1957): The Poverty of Historicism. London, Routledge.
Popper, Karl Raimund (1963): Conjectures and Refutations: The Growth of Scientific Knowledge. London, Routledge.
Popper, Karl Raimund (1972): Objective Knowledge: An Evolutionary Approach. London, Oxford University Press.
Popper, Karl Raimund (1974): “Autobiography of Karl Popper”, in The Philosophy of Karl Popper (ed. P. A. Schillp), La Salle, Illinois, Open Court.
Popper, Karl Raimund (1970). “Normal Science and its Dangers” in Lakatos and Musgrave eds, (1970).
Popper, Karl Raimund (1974). “Intellectual Autobiography” in Schilpp, (ed.), (1974), pp. 3-181.
Popper, Karl Raimund (1976): Unended Quest: An Intellectual Autobiography. Glasgow, Fontana/Collins.
Popper, Karl Raimund (1982): Quantum Theory and the Schism in Physics. London, Hutchinson & Co.
Popper, Karl Raimund (1983). Realism and the Aim of Science. London, Hutchinson & Co.
Schilpp, Paul Alfred (ed.) (1974): The Philosophy of Karl Popper, Library of Living Philosophers Series. La Salle, Open Court.
Simkin, Colin (1993): Popper’s Views on Natural and Social Science. Leiden, Brill.
Smith, Barry (1990): “Aristotle, Menger, Mises: An Essay in the Metaphysics of Economics”, Caldwell, (ed.) (1990), pp. 263-288.
Smith, Barry. (1994): Austrian Philosophy. The Legacy of Franz Brentano. Chicago and LaSalle, Illinois, Open Court.
Smith, Barry (1996): “In Defense of Extreme (Fallibilistic) Apriorism”, in Journal of Libertarian Studies, Volume 12, pp. 179-192.
Wong, Stanley (2006): Foundations of Paul Samuelson’s Revealed Preference Theory: A Study by the Method of Rational Reconstruction. London, Routledge.
