Mises claims that praxeology is a deductive science like mathematics or geometry, and that the validity of its conclusions (Y) derive from the consistency of its reasoning from its original premises (X).
As Robbins explains:
“Economic laws describe inevitable implications. If the data they postulate [X] are given, then the consequences they predict [Y] necessarily follow. In this sense they are on the same footing as other scientific laws, and as little capable of “suspension.” If, in a given situation, the facts [X] are of a certain order, we are warranted in deducing with complete certainty that other facts [Y] which it enables us to describe are also present. …If the “given situation” [X] conforms to a certain pattern, certain other features [Y] must also be present, for their presence is “deducible” from the pattern originally postulated.” (An Essay on the Nature & Significance of Economic Science)(X’s and Y’s added by AK)
What exactly is Mises’s original premis or axiom? He claims that people aim at ends; that they attempt to replace the situation confronting them with a different situation.
“In an a prioristic science, we start with a general supposition—action is taken to substitute one state of affairs for another.”
(The Free Market and its Enemies, p. 16)
“The starting point of praxeology is a self-evident truth, the cognition of action, that is, the cognition of the fact that there is such a thing as consciously aiming at ends.”
(The Ultimate Foundation of Economic Science, p. 5)
Regarding praxeology in its most general and universal form, Mises is saying that the “X” which we assume, and from which we deduce Y, is the assumption or supposition of action. We assume X: that an actor attempts to replace the current situation with a different situation.
If we accept X, and if we accept the validity of his deductions, then we must accept Y.
Given that praxeology is a discipline as described above, what reason might there be for denying Mises’s premise or grounding axiom—the supposition of action?
From the point of view of natural science, one might reject Mises’s premise for the following reason.
The natural scientist may argue that while he accepts the “psychological” fact of action, he rejects the “ontological” fact of action. This means that while it may be true that I experience something like aiming at ends “inside my head,” the progress of natural science is likely to demonstrate, eventually, that the feeling I have, and which I believe is self-evident proof that I do aim at ends, is really (ontologically) just the relationships of particles in fields of force. That which I experience as my own aiming at ends, science will one day fully explain in physical terms. And thus, the ontological fact (what is real) is not action, but particles in fields of force. The subjective fact of action, the natural scientist may argue, is a subsidiary or residual effect of physical processes. The subjective phenomenon of action is of a lower ontological status than the phenomena of physics.
The phenomenon of action belongs to a specific class of like phenomena. Action (the experience I have of it in my head) belongs to the same class of phenomena as a mirage. One may see a mirage with one’s eyes, and one may accept this “psychological” fact. But one may also deny that the mirage is an “ontological” fact. What a mirage “really is,” is a certain arrangement of particles and forces. What I “subjectively” see as a mirage turns out to be illusory. What I see as a mirage is not “really” there. My own actions which I personally experience are of this same essential nature. One day the phenomenon of “action” and all other phenomena of consciousness will be explained entirely in terms of physical processes and then we will see that my subjective experience of aiming at ends is as illusory as a mirage. For this reason, we natural scientists reject the notion that action “exists” or that “man acts.” What exists are particles in fields of force. We thus reject Mises’s premise that there is such a thing as consciously aiming at ends.
This argument from natural science is impervious to any evidence of action based on self-reflection or observation. It is also impervious to the assertion, made by some Austrians, that in arguing against the axiom of action, one is acting. The naturalist may freely admit that he experiences, subjectively, something that may be referred to as action. But these internal “feelings” aren’t science. I may subjectively experience that glass is solid, but science shows us that glass is actually a liquid. Science will eventually explain how our subjective experience of aiming at ends is actually something else.
The naturalist will argue that science is natural science, which means the description of phenomena in terms of particles and forces. As science progresses, it describes in scientific terms, things which were once described in terms of opinions, appearances, sensations, and superstitions. Any discipline that relies on a description of things in terms of opinions, appearances, sensations, and superstitions, is, by definition, in a nonscientific state of development. A premise described in these terms is, by definition, a nonscientific premise. It is built on “subjective illusion” not on scientific fact.
The effectiveness of this argument derives from the naturalist premise that science will, in the future, succeed in explaining all phenomena of consciousness in terms of physical processes. This premise implies that the subjective phenomena of consciousness are essentially nonscientific in nature, and will, in the future, be given a purely scientific physical explanation. Until science succeeds in this endeavor, subjective verbal accounts of mental phenomena such as “action” remain, by definition, in a nonscientific state of development.
Science is the progressive description of subjective phenomena (things as they appear to us) in terms of objective phenomena (things as they really are). This is the natural-scientific premise. The premise entails the rejection of subjective appearances as evidence of the ontological (i.e., real) existence of things. Only scientific evidence given in terms of physical processes qualify as scientific evidence.
To the extent the axiom of action is derived from subjective evidence of the existence of action, it must be rejected as fundamentally unscientific in character. This follows from the natural-scientific premise.
A theory that supposes the existence of action and that reasons beginning from this supposition, requires an argument showing how or why the natural-scientific premise is faulty.