Popper vs von Mises on the philosophy of science


A long thread on the Critical Rationalist facebook page began by drawing on  von Mises’s criticism of Popper in The Ultimate Foundation of Economic Science “he [von Mises] addressed the claim of Karl Popper that scientific propositions must be falsifiable. Although Popper was not a positivist, he intended his falsification criterion to separate scientific from non-scientific statements.”

That is not a helpful statement without providing an account of the problem situation which the positivists and Popper addressed. For the positivists, the use of the inductive method was a distinctive feature of science, but Popper considered that induction was logically incoherent.  Instead, he was looking for a convention make a clear distinction between (a) theories that claimed to be scientific (due to their alleged basis on evidence) which are nevertheless not refutable and (b) theories that do lay themselves open to falsification (in principle).

As described in The Guide to The Logic of Scientific Discovery,  he made a significant departure from the usual approaches to decide these matters, either by logical analysis or by observation of the way scientists work (the naturalistic approach). He articulated the “rules of the game” or “conventions” approach. This is closely related to his rejection of certainty as an aim of science . He introduced the theme of conjectural knowledge as a permanent feature of scientific theories and not a transient situation or a “bug” in a new theory, to be superseded by further investigation and “confirmation”.

His criterion of demarcation is a proposal for an agreement or convention. He noted that his convention will be rejected by people who think that science can generate a system of “absolutely certain, irrevocably true statements”.

The test for his proposals is to examine their logical consequences, and to explore their fertility in solving problems in the theory of knowledge and scientific investigation. Essentially, it is a test of practice and practical results.

One of the practical implications of  Popper’s criterion is that it can be used early in an argument to discover where the various parties stand on the use of evidence in the debate. It also prompts scientist to be constantly mindful of the importance of testing, with all that implies for the design of experiments and the attitude adopted towards adverse findings.

Popper’s program was radically different from the positivists, a fact obscured by people who can only see Popper’s falsifiability criterion as a rival of the positivists criterion of MEANING  (they royally confused the issue by taking up testability as a criterion of meaning, as though Popper was working on the same problem).

Part of the problem here is the great significance ascribed to Science in the wake of Newton, when Science gained the reputation for finding ultimate truths. Previously the terms science or scientific merely implied  systematic investigation with a view to  obtaining useful principles, and so there was the science of angling and every other thing.

Part of the power of Popper’s program was to get away from the hopeless quest of the positivists/empiricists for a criterion of meaning (or cognitive significance) and the attempt to save inductive logic. The falsifiability criterion had logical coherence which the verification  criterion lacked, and although falsification could not be decisive in practice, it did have the practical effect of pointing up the need for more critical attention to conventions to guide scientific practice (hence the program charted by Ian Jarvie).

One more important point: the focus of critical discussion for Popper was/were the laws of science, expressed as universal generalizations. That is what makes the logic of testing so strong (compared with verification).  I don’t understand how  a pure logical analysis  can demonstrate  that both the verification criterion and the falsifiability criterion are worthless.   What is the point of Popper’s demarcation principle, given the larger contours of his program? Where is the universal statement that is tested by the basic statement “there is a chair in this room”? Is it a universal statement of any interest in the real world of scientific investigation?

This is the original argument.

In point of fact, the criterion is worthless, since every statement comes out verifiable under it. Suppose that “p” is a non-controversially verifiable statement, e.g., “there is a chair in this room.” Let us take “q” to be a statement logical positivists reject as meaningless. A good example is one that Rudolf Carnap held up to ridicule when he called for an end to metaphysics. He cited the following from Martin Heidegger’s Being and Time (1927): “The not nothings itself.” I shall not attempt to explain this: one can see why Carnap presented it as a paradigm instance of a meaningless statement.

Does the verification principle eliminate it? Surprisingly, it does not. From p, we deduce p or q. (This step is non-controversial.) Assuming that a logical consequence of a verifiable proposition is itself verifiable, (p or q) is verifiable. Further, if p is verifiable, then the negation of p is verifiable; this principle seems difficult to question. Now, consider this argument:

p or q not -p ______ q
This argument is valid, and each of its premises is verifiable. Then, q is a logical consequence of verifiable propositions, and it, too, is verifiable. Clearly, if the verification criterion cannot eliminate “the not nothings itself,” it is not worth very much.

A falsification criterion fairs no better. If p is falsifiable, then (p and q) is falsifiable. Once more, not-p should be falsifiable if p is, though Karl Popper has implausibly denied this. By an argument parallel with that for verification, we conclude that q is falsifiable.

One might think that this is a mere trick, readily avoidable through slight modification of the principle. There have been many attempts to formulate a criterion that comes up with the “right” results, but so far all have failed to withstand criticism.

What is the “right result”  or the criterion for a “right result”?

Looked at in the context of testing (universal) scientific theories, what is wrong with the principle of falsifiability in logic and in practice for working scientists?  With scientifically relevant statements in place of the ps and qs in the argument above would the result still look like a knockdown victory over Popper’s arguments?
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10 Responses to Popper vs von Mises on the philosophy of science

  1. Bruce Caithness says:

    Some points on falsifiability and verifiability as LOGICAL properties of statements and the METHODOLOGICAL matter of falsification and verification follow.

    Let us look generically at the the LOGIC:

    To falsify a proposition is to show that it is false. A proposition is falsifiable IFF it is POSSIBLE to test it in a way which would show it to be false if it were false. (So a proposition could be both true and falsifiable).


    To verify a proposition is to show that it is true. A proposition is verifiable IFF it is POSSIBLE to test it in a way which would show it to be true if it were true. (So a proposition could be both false and verifiable).

    The above are modified from Sparkes, A. W. “Talking Philosophy:A Workbook” (1991)

    Now let us look at EXAMPLES:

    Sparkes gives the example of a statement, “There is a 5 foot mermaid sitting on the edge of the kitchen table”. This is both verifiable and falsifiable.

    “There are mermaids” is verifiable as would be demonstrated if someone produced a genuine mermaid.

    “Every crow is black”, a universal statement, is not verifiable however as it ranges over all the crows that there were, are or ever would be.

    “Every crow is black” , a universal statement, is falsifiable as can be demonstrated if one non-black crow is produced.

    What is clear from above is that universal statements (theories) are falsifiable but not verifiable. Again, this is a matter of logic.

    OK that is fine, but what about the METHODOLOGICAL issues around the acceptance of evidence? This is where falsification and verification become matters of decision in practice, as distinguished from the logic of falsifiability and verifiability. We have to make decisions as to whether to accept that the mermaid exists or not, if it is a genuine mermaid that we see, or that the perceived black object is indeed black and also a crow.

    This is emphasized in Rafe Champion’s writings and the above post. Ian C. Jarvie’s “The Republic of Science, The Emergence of Popper’s Social View of Science, 1935-1945” (2001) is a core work on the importance of the rules of the game of science. It is available on GooglePlay.

  2. Matt says:

    Just for people who are looking for links.

    Here is a link to David Gordon’s paper, “The Philosophical Origins of Austrian Economics”:

    Here is the link to the discussion on Facebook:

  3. Kenneth Hopf says:


    I like your contribution above. Unfortunately, however, I feel compelled to raise what must certainly look like a silly quibble. I don’t really think it is, but I would understand if people felt otherwise. That is, the term ‘falsify’ is really the verb form of ‘falsification’ — not the verb form of ‘falsifiability’. The same thing goes for ‘verify’, ‘verification’, and ‘verifiability’.

    This makes an important difference, because it means, among other things, that the element of decision enters the method sooner rather than later. In particular, one must reject the paraphrase from Sparkes: “To falsify a proposition is to show that it is false.” Most emphatically, a falsification does not SHOW that anything is false. What we should rather say is that to falsify is to DECIDE a proposition is false, and to verify is to DECIDE a proposition is true.

    Of course, I realize that words are just instruments, and that we can salvage the original formulation with a bit of arm twisting. My experience has been, however, that the critics are nowhere near so obliging or willing to focus on gaining an understanding rather than winning an argument and illustrating gleefully what they imagine to be the foolishness of critical rationalists. I am not inclined to hand them opportunities on a silver platter.

    When you think about it, there’s really not much difficulty in re-introducing positivism and justificationism on the back of a statement like “To falsify a proposition is to show that it is false.” I’m sure you see why, so I’ll leave it at that.

  4. Kenneth Hopf says:


    And better yet, of course, one might say something like: “To falsify a proposition is to classify it as false, whether it actually is false or not.”

    This really knocks the pins out from under those critics who insist that critical rationalism is just a form of positivist justificationism turned on its heads. Don’t ever give them an inch, because they will strive to turn it into a mile.

  5. Bruce Caithness says:


    I differ on the etymology, but I do not know your sources.

    From my checking with the Shorter Oxford Dictionary falsify is a verb for either falsifiability or falsification. ORIGIN: Old French falsifier from medieval Latin falsificare, from Latin falsificus making false, from falsus false.

    By dictionary definition, it means to make or show to be false.

    As Popper says every genuine attempt to test a theory is an attempt to falsify it, or to refute it.

    In practice even if a theory is falsifiable in principle the attempt at falsification is rarely if ever conclusive. Hence the distinction, even if we classify it as falsified, it may actually not be false.

  6. Rob Rosenbaum says:

    von Mises is wrong to claim that if p is falsifiable, then not-p is also falsifiable. I don’t know what Popper’s argument was, but mathematics is full of examples. In general, “No number has property P” is always falsifiable, if property P is something you can check for in a finite number of steps. However, “Some number has property P” may not be falsifiable, since falsifying it might require checking all numbers ad infinitum. An example from physical science: “No other planet has life on it” is falsifiable, but “Some other planet has life on it” may not be. “There is no chair in this room” happens to be falsifiable, but only because a room is a finite space.

  7. Rafe says:

    Yes Rob, thanks!

  8. Bruce Caithness says:

    Popper’s 1982 Introduction in “Realism and the Aim of Science from the Postscript to the Logic of Scientific Discovery” (1983) gives an accessible and clear synopsis of his views on falsifiability and falsification during this period when W.W. Bartley was editing the Postscript.

    Popper reiterates that “falsifiable” as a logical-technical term, falsifiable in principle, is to be distinguished from the sense that a theory can be definitely or conclusively or demonstrably be falsified. He continues, “I have always stressed that even a theory which is obviously falsifiable in the first sense is never falsifiable in the second sense. (For this reason I have used the term ‘falsifiable’ as a rule only in the first, technical sense. In the second sense I have as a rule spoken not of ‘falsifiability’ but rather of ‘falsification’ and of its problems.”

  9. Rainer Moeller says:

    I wonder about “situational logic”. It’s propagated in “The Open Society” as a distinct method in the study of man, and I’ve always assumed that Popper was inspirated here by Austrian economics, as he had got to know it from Mises. But as far as I remember, he didn’t discuss wether and how situational logics can be falsified.
    There are of course some theorists who have tried to treat situational explanations as grounded in theorems which can be falsified empirically – and on the other hand theorists who pretend that such theorems are mere truisms. As Popper spoke about “logic” here, he seems to have supported a non-empirical approach.

  10. Rafe says:

    Popper’s most thorough treatment of situational analysis and the rationality principle occurs in “Models, Instruments and Truth: The status of the rationality principle in the social sciences”. He wrote that his aim was to generalize the method of neoclassical economics, possibly due to the influence of his young economist friend in NZ, Colin Simkin who was no Austrian. He was aware of the work of Carl Menger and referred to his essays in The Poverty but I don’t think he ever referred to the methodology of von Mises.

    Somewhere he wrote that he changed his terminology from the logic of the situation to situational analysis to take the emphasis off logic, and place it on analysis of the situation.

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