If we are prepared to take the term causality in its broadest sense, teleology can be called a variety of causal inquiry. Final causes are first of all causes. The cause of an event is seen as an action or quasi-action aiming at some end.
Both primitive man and the infant, in a naive anthropomorphic attitude, consider it quite plausible that every change and event is the outcome of the action of a being acting in the same way as they themselves do. They believe that animals, plants, mountains, rivers, and fountains, even stones and celestial bodies, are, like themselves, feeling, willing, and acting beings. Only at a later stage of cultural development does man renounce these animistic ideas and substitute the mechanistic world view for them. Mechanicalism proves to be so satisfactory a principle of conduct that people finally believe it capable of solving all the problems of thought and scientific research. Materialism and panphysicalism proclaim mechanicalism as the essence of all knowledge and the experimental and mathematical methods of the natural sciences as the sole scientific mode of thinking. [p. 24]
All changes are to be comprehended as motions subject to the laws of mechanics.
The champions of mechanicalism do not bother about the still unsolved problems of the logical and epistemological basis of the principles of causality and imperfect induction. In their eyes these principles are sound because they work. The fact that experiments in the laboratory bring about the results predicted by the theories and that machines in the factories run in the way predicted by technology proves, they say, the soundness of the methods and findings of modern natural science. Granted that science cannot give us truth--and who knows what truth really means?--at any rate it is certain that it works in leading us to success.
But it is precisely when we accept this pragmatic point of view that the emptiness of the panphysicalist dogma becomes manifest. Science, as has been pointed out above, has not succeeded in solving the problems of the mind-body relations. The panphysicalists certainly cannot contend that the procedures they recommend have ever worked in the field of interhuman relations and of the social sciences. But it is beyond doubt that the principle according to which an Ego deals with every human being as if the other were a thinking and acting being like himself has evidenced its usefulness both in mundane life and in scientific research. It cannot be denied that it works.
It is beyond doubt that the practice of considering fellow men as beings who think and act as I, the Ego, do has turned out well; on the other hand the prospect seems hopeless of getting a similar pragmatic verification for the postulate requiring them to be treated in the same manner as the objects of the natural sciences. The epistemological problems raised by the comprehension of other people's behavior are no less intricate than those of causality and incomplete induction. It may be admitted that it is impossible to provide conclusive evidence for the propositions that my logic is the logic of all other people and by all means absolutely the only human logic and that the categories of my action are the categories of all other people's action and by all means absolutely the categories of all human action. However, the pragmatist must remember that these propositions work both in practice and in science, and the positivist must not overlook the fact that in addressing his fellow men he presupposes --tacitly and implicitly-- the intersubjective validity of logic and thereby the reality of the realm of the alter Ego's thought and action, of his eminent human character [p. 25] .
Thinking and acting are the specific human features of man. They are peculiar to all human beings. They are, beyond membership in the zoological species homo sapiens, the characteristic mark of man as man. It is not the scope of praxeology to investigate the relation of thinking and acting. For praxeology it is enough to establish the fact that there is only one logic that is intelligible to the human mind, and that there is only one mode of action which is human and comprehensible to the human mind. Whether there are or can be somewhere other beings--superhuman or subhuman--who think and act in a different way, is beyond the reach of the human mind. We must restrict our endeavors to the study of human action.
This human action which is inextricably linked with human thought is conditioned by logical necessity. It is impossible for the human mind to conceive logical relations at variance with the logical structure of our mind. It is impossible for the human mind to conceive a mode of action whose categories would differ from the categories which determine our own actions.
There are for man only two principles available for a mental grasp of reality, namely, those of teleology and causality. What cannot be brought under either of these categories is absolutely hidden to the human mind. An event not open to an interpretation by one of these two principles is for man inconceivable and mysterious. Change can be conceived as the outcome either of the operation of mechanistic causality or of purposeful behavior; for the human mind there is no third way available . It is true, as has already been mentioned, that teleology can be viewed as a variety of causality. But the establishment of this fact does not annul the essential differences between the two categories.
The panmechanistic world view is committed to a methodological monism; it acknowledges only mechanistic causality because it attributes to it alone any cognitive value or at least a higher cognitive value than teleology. This is a metaphysical superstition. Both principles of cognition--causality and teleology--are, owing to the limitations of human reason, imperfect and do not convey ultimate knowledge. Causality leads to a regressus in infinitum which reason can never exhaust. Teleology is found wanting as soon as the question is raised of what moves the prime mover. Either method stops short at an ultimate given which cannot be analyzed and interpreted. Reasoning and scientific inquiry can never bring full ease of mind, apodictic certainty, and perfect cognition of all things. He who seeks [p. 26] this must apply to faith and try to quiet his conscience by embracing a creed or a metaphysical doctrine.
If we do not transcend the realm of reason and experience, we cannot help acknowledging that our fellow men act. We are not free to disregard this fact for the sake of a fashionable prepossession and an arbitrary opinion. Daily experience proves not only that the sole suitable method for studying the conditions of our nonhuman environment is provided by the category of causality; it proves no less convincingly that our fellow men are acting beings as we ourselves are. For the comprehension of action there is but one scheme of interpretation and analysis available, namely, that provided by the cognition and analysis of our own purposeful behavior.
The problem of the study and analysis of other people's action is in no way connected with the problem of the existence of a soul or of an immortal soul. As far as the objections of empiricism, behaviorism, and positivism are directed against any variety of the soul-theory, they are of no avail for our problem. The question we have to deal with is whether it is possible to grasp human action intellectually if one refuses to comprehend it as meaningful and purposeful behavior aiming at the attainment of definite ends. Behaviorism and positivism want to apply the methods of the empirical natural sciences to the reality of human action. They interpret it as a response to stimuli. But these stimuli themselves are not open to description by the methods of the natural sciences. Every attempt to describe them must refer to the meaning which acting men attach to them. We may call the offering of a commodity for sale a "stimulus." But what is essential in such an offer and distinguishes it from other offers cannot be described without entering into the meaning which the acting parties attribute to the situation. No dialectical artifice can spirit away the fact that man is driven by the aim to attain certain ends. It is this purposeful behavior--viz., action--that is the subject matter of our science. We cannot approach our subject if we disregard the meaning which acting man attaches to the situation, i.e., the given state of affairs, and to his own behavior with regard to this situation.
It is not appropriate for the physicist to search for final causes because there is no indication that the events which are the subject matter of physics are to be interpreted as the outcome of actions of a being, aiming at ends in a human way. Nor is it appropriate for the praxeologist to disregard the operation of the acting being's volition and intention; they are undoubtedly given facts. If he were to disregard it, he would cease to study human action. Very often--but not always--the events concerned can be investigated both [p. 27] from the point of view of praxeology and from that of the natural sciences. But he who deals with the discharging of a firearm from the physical and chemical point of view is not a praxeologist. He neglects the very problems which the science of purposeful human behavior aims to clarify.
On the Serviceableness of Instincts
The proof of the fact that only two avenues of approach are available for human research, causality or teleology, is provided by the problems raised in reference to the serviceableness of instincts. There are types of behavior which on the one hand cannot be thoroughly interpreted with the causal methods of the natural sciences, but on the other hand cannot be considered as purposeful human action. In order to grasp such behavior we are forced to resort to a makeshift. We assign to it the character of a quasi-action; we speak of serviceable instincts.
We observe two things: first the inherent tendency of a living organism to respond to a stimulus according to a regular pattern, and second the favorable effects of this kind of behavior for the strengthening or preservation of the organism's vital forces. If we were in a position to interpret such behavior as the outcome of purposeful aiming at certain ends, we would call it action and deal with it according to the teleological methods of praxeology. But as we found no trace of a conscious mind behind this behavior, we suppose that an unknown factor--we call it instinct--was instrumental. We say that the instinct directs quasi-purposeful animal behavior and unconscious but nonetheless serviceable responses of human muscles and nerves. Yet, the mere fact that we hypostatize the unexplained element of this behavior as a force and call it instinct does not enlarge our knowledge. We must never forget that this word instinct is nothing but a landmark to indicate a point beyond which we are unable, up to the present at least, to carry our scientific scrutiny.
Biology has succeeded in discovering a "natural," i.e., mechanistic, explanation for many processes which in earlier days were attributed to the operation of instincts. Nonetheless many others have remained which cannot be interpreted as mechanical or chemical responses to mechanical or chemical stimuli. Animals display attitudes which cannot be comprehended otherwise than through the assumption that a directing factor was operative.
The aim of behaviorism to study human action from without with the methods of animal psychology is illusory. As far as animal behavior goes beyond mere physiological processes like breathing and metabolism, it can only be investigated with the aid of the meaning-concepts developed by praxeology. The behaviorist approaches the [p. 28] object of his investigations with the human notions of purpose and success. He unwittingly applies to the subject matter of his studies the human concepts of serviceableness and perniciousness. He deceives himself in excluding all verbal reference to consciousness and aiming at ends. In fact his mind searches everywhere for ends and measures every attitude with the yardstick of a garbled notion of serviceableness. The science of human behavior--as far as it is not physiology--cannot abandon reference to meaning and purpose. It cannot learn anything from animal psychology and the observation of the unconscious reactions of newborn infants. It is, on the contrary, animal psychology and infant psychology which cannot renounce the aid afforded by the science of human action. Without praxeological categories we would be at a loss to conceive and to understand the behavior both of animals and of infants.
The observation of the instinctive behavior of animals fills man with astonishment and raises questions which nobody can answer satisfactorily. Yet the fact that animals and even plants react in a quasi-purposeful way is neither more nor less miraculous than that man thinks and acts, that in the inorganic universe those functional correspondences prevail which physics describes, and that in the organic universe biological processes occur. All this is miraculous in the sense that it is an ultimate given for our searching mind.
Such an ultimate given is also what we call animal instinct. Like the concepts of motion, force, life, and consciousness, the concept of instinct too is merely a term to signify an ultimate given. To be sure, it neither "explains" anything nor indicates a cause or an ultimate cause. 
The Absolute End
In order to avoid any possible misinterpretation of the praxeological categories it seems expedient to emphasize a truism.
Praxeology, like the historical sciences of human action, deals with purposeful human action. If it mentions ends, what it has in view is the ends at which acting men aim. If it speaks of meaning, it refers to the meaning which acting men attach to their actions.
Praxeology and history are manifestations of the human mind and as such are conditioned by the intellectual abilities of mortal men. Praxeology and history do not pretend to know anything about the intentions of an absolute and objective mind, about an objective meaning inherent in the course of events and of historical evolution, and about the plans which God or Nature or Weltgeist or Manifest [p. 29] Destiny is trying to realize in directing the universe and human affairs. They have nothing in common with what is called philosophy of history. They do not, like the works of Hegel, Comte, Marx, and a host of other writers, claim to reveal information about the true, objective, and absolute meaning of life and history.
Some philosophies advise men to seek as the ultimate end of conduct the complete renunciation of any action. They look upon life as an absolute evil full of pain, suffering, and anguish, and apodictically deny that any purposeful human effort can render it tolerable. Happiness can be attained only by complete extinction of consciousness, volition, and life. The only way toward bliss and salvation is to become perfectly passive, indifferent, and inert like the plants. The sovereign good is the abandonment of thinking and acting.
Such is the essence of the teachings of various Indian philosophies, especially of Buddhism, and of Schopenhauer. Praxeology does not comment upon them. It is neutral with regard to all judgments of value and the choice of ultimate ends. Its task is not to approve or to disapprove, but to describe what is.
The subject matter of praxeology is human action. It deals with acting man, not with man transformed into a plant and reduced to a merely vegetative existence. [p. 30]
 Cf. Alfred Schütz, Der sinnhafte Aufbau der sozialen Welt (Vinna, 1932), p. 18.
 Cr. Karel Englis, Begründung der Teleologie als Form des empirischen Erkennens (Brünn, 1930), pp. 15 ff.
 "La vie est une cause premiere qui nous échappe comme toutes les causes premières et dont la science expérimentale n'a pas à se préoccuper." Claude Bernard, Law Science expérimentale (Paris, 1878), p. 137.
 On the philosophy of history, cf. Mises, Theory and History (New Haven, 1957), pp. 159. ff.