I am considering the wisdom of Karl Popper regarding the falsification criterion. It is describe, inter alia, in www.britannica.com according to which "He /Karl Popper/ held that genuinely scientific theories are never finally confirmed, because disconfirming observations (observations that are inconsistent with the empirical predictions of the theory) are always possible no matter how many confirming observations have been made."

Karl Popper made his observation in "The Logic of Scientific Discovery" (1934). (It seems that about 650 years before, Tomas Aquinas made a similar observation in "Summa theologica" in passing: "Reason is employed in another way, not as furnishing a sufficient proof of a principle, but as confirming an already established principle, by showing the congruity of its results, as in astrology the theory of eccentrics and epicycles is considered as established, because thereby the sensible appearances of the heavenly movements can be explained; not, however, as if this proof were sufficient, forasmuch as some other theory might explain them" - Question 32. The knowledge of the divine persons, Reply to Objection 2).

Let us now take a closer view of the concept of a theory. Popper’s idea of the goal of a theory or model is verisimilitude, a likeness of the model or theory to the real world. The question Popper is addressing is whether a claim of truthfulness can or cannot be made for such models or theories.

We note that the movements of the planets can be described almost exactly by the Solar system model of Newton but we also note that there is nothing in the system to which the central concept in the Newtonian mechanics theory, gravitation, can be compared in the real world.

If we then make a distinction between theory and models, which are based on the theory, we note that the claim of truthfulness or verisimilitude cannot even be formulated in a meaningful and consistent way for the theory (of Newtonian mechanics). This can only occur in the case of the models. Newton’s gravity cannot be compared to any other concept in the objective world.

I am surprised that this distinction is not mentioned more in the literature. Under the heading Karl Popper, Stanford Encyclopedia of Philosophy has mentions of the word “theory” 100 times and the word “model” is not mentioned at all. Perhaps it is mentioned elsewhere in the literature. I am thankful for any help in this matter.

  • The no-comparison claim re: Newtonian gravity is reminiscent of the question as to whether (some sets of) scientific theories are strictly incommensurable. Aug 26 at 22:49
  • Popper's demarcation problem (falsifiability as true testability) mainly concerns the criterion of empiric scientific theories, neither their truth nor their meaning/significance or explanatory power are of his interest at all. A scientist would be of course more interested in various possible competitive models or causal structural equations to (sufficiently) explain the necessity or possibility of a said theory, for example, Descartes/Huygens vortex model, Hook's wave model, Newton's own stream model with Riemann's math detailing, Euler's pressure model to explain Newton's gravity theory... Aug 26 at 23:15
  • - as you note in my quotation from Britanica, above the ideas of Popper is understood to go much further than demarcation, closer to the issues you mention yourself. It follows from the quote that they are - rightly or not - also seen as going beyond comparison and adressing absolute truth. Aug 27 at 9:59
  • Maybe you have to qualify "models" compared to scientific theories.Joseph Sneed tried to apply model theory (following Suppes) to physical theories. Aug 27 at 12:58
  • Popper in his own 1963 retro explicitly mentioned neither truth/acceptability nor meaning/significance/explanatory power are of target of his demarcation problem of science. Of course besides this he may tried to solve the holy grail truth problem by his verisimilitude which was a failed project to carve nature at its joints. Recently there's a post from a mathematician trying to confirm applicability of hyperreal nonstandard model of Robinson's infinitesimal theory... Aug 27 at 23:29


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