Apriorismo, Economia e Humpty Dumpty

Leitura recomendada (especialmente ao Manuel Pinheiro, ao Tiago Mendes e, claro, ao João Galamba; o parágrafo sobre o trabalho empírico levado a cabo por Hayek é particularmente recomendado ao Carlos Novais): What Is A Priori Science, and Why Does Economics Qualify As One?, por Gene Callahan.

As I understand him, by categorizing the fundamental principles of economics as a priori truths and not contingent facts open to empirical discovery or refutation, Mises was not claiming that economic law is revealed to us by divine action, like the ten commandments were to Moses. Nor was he proposing that economic principles are hard-wired into our brains by evolution, nor even that we could articulate or comprehend them prior to gaining familiarity with economic behavior through participating in and observing it in our own lives. In fact, it is quite possible for someone to have had a good deal of real experience with economic activity and yet never to have wondered about what basic principles, if any, it exhibits.

Nevertheless, Mises was justified in describing those principles as a priori, because they are logically prior to any empirical study of economic phenomena. Without them it is impossible even to recognize that there is a distinct class of events amenable to economic explanation. It is only by pre-supposing that concepts like intention, purpose, means, ends, satisfaction, and dissatisfaction are characteristic of a certain kind of happening in the world that we can conceive of a subject matter for economics to investigate. Those concepts are the logical prerequisites for distinguishing a domain of economic events from all of the non-economic aspects of our experience, such as the weather, the course of a planet across the night sky, the growth of plants, the breaking of waves on the shore, animal digestion, volcanoes, earthquakes, and so on.

Unless we first postulate that people deliberately undertake previously planned activities with the goal of making their situations, as they subjectively see them, better than they otherwise would be, there would be no grounds for differentiating the exchange that takes place in human society from the exchange of molecules that occurs between two liquids separated by a permeable membrane. And the features which characterize the members of the class of phenomena singled out as the subject matter of a special science must have an axiomatic status for practitioners of that science, for if they reject them then they also reject the rationale for that science's existence.

Economics is not unique in requiring the adoption of certain assumptions as a pre-condition for using the mode of understanding it offers. Every science is founded on propositions that form the basis rather than the outcome of its investigations. For example, physics takes for granted the reality of the physical world it examines. Any piece of physical evidence it might offer has weight only if it is already assumed that the physical world is real. Nor can physicists demonstrate their assumption that the members of a sequence of similar physical measurements will bear some meaningful and consistent relationship to each other. Any test of a particular type of measurement must pre-suppose the validity of some other way of measuring against which the form under examination is to be judged.

(...)

One can understand and assent to the core truth about economics that Mises stressed, but nevertheless part ways with him over exactly what that truth means to the pursuit of economic science. For example, Mises's protégé F.A. Hayek, while agreeing with his mentor on the a priori nature of the "logic of action" and its foundational status in economics, still came to regard investigating the empirical issues that the logic of action leaves open as a more important undertaking than further examination of that logic itself.

(...)

Michael Polanyi has shown that intuitive judgment is the final arbiter even in the "hard" sciences like physics and chemistry.

While experimental findings are, quite properly, a major factor in a scientist's choice of which of two rival theories to accept, the scientist's personal, intuitive judgment will always have the final say in the matter. When the results of an experiment are in conflict with a theory, the flaw may be in either the theory or the experiment. In the end, it is up to the scientist to choose which to discard, a question that cannot be answered by the very empirical results in doubt.
This ultimate, inescapable reliance on judgment is illustrated by Lewis Carroll in Alice Through the Looking Glass. He has Alice tell Humpty Dumpty that 365 minus one is 364. Humpty is skeptical, and asks to see the problem done on paper. Alice dutifully writes down:

365
- 1
___
364

Humpty Dumpty studies her work for a moment before declaring that it seems to be right. The serious moral of Carroll's comic vignette is that formal tools of thinking are useless in convincing someone of their conclusions if he hasn't already intuitively grasped the basic principles on which they are built.

All of our knowledge ultimately is grounded on our intuitive recognition of the truth when we see it. There is nothing magical or mysterious about the a priori foundations of economics, or at least nothing any more magical or mysterious than there is about our ability to comprehend any other aspect of reality. [destaque e itálico meus]