Human action is purposeful behavior.
Paraphrased, action is will put into operation, aiming at ends and goals, the ego's meaningful response to stimuli and to the conditions of its environment, a person's conscious adjustment to the state of the universe that determines his life. The end of an action is always the alleviation of some felt uneasiness. All human beings act by virtue of their existence and their nature as human beings.
An end is everything which men aim at. A means is everything acting men consider as such.
In order to act, man must have more than unachieved ends: he must also expect that some action will enable him to attain them. A man may have a desire for sunshine, but if he realizes that he can do nothing to achieve it, he does not act on this desire. He must have certain ideas about how to achieve his ends. Action thus consists of the behavior of indiÂviduals directed towards ends in ways that they believe will acÂcomplish their purpose. Action requires an image of a desired end and â€śtechnological ideasâ€ť or plans on how to arrive at this end.
The individual actor is faced with an environment that he would like to change in order to attain his ends. Man can work only with the elements that he finds in his environment, by rearÂranging them to bring about the satisfaction of his ends. The environment may be divided into two parts: those elements which he believes he cannot control and must leave unchanged, and those which he can alter (or thinks he can alter) to arrive at his ends. The former may be termed the general conditions of the action; the latter, the means used.
Every act must therefore involve the employment of means by individual actors to attempt to arÂrive at certain desired ends. The genÂeral conditions cannot be the objects of any human action; only the means can be employed in action.
 Action and Time
All human life must take place in time. When a human being decides to act, his goal, or end, can be finally and comÂpletely attained only at some point in the future. If all ends could be reached immediately, there would be no need to act.
For any given action, we can distinguish among three periods of time involved: the period before the action, the time absorbed by the action, and the period after the action has been completed. All action aims at rendering conditions at some time in the future more satisfactory for the actor than they would have been without the intervention of the action.
A manâ€™s time is always scarce. He is not immortal; his time on earth is limited. Each day of his life has only 24 hours in which he can attain his ends. Furthermore, all actions must take place through time. Therefore time is a means that man must use to arrive at his ends. It is a means that is omnipresent in all human action.
A fundamental implication is the uncertainty of the future. If man knew future events completely, he would never act, since no act of his could change the situation. This uncertainty about future events stems from two basic sources: the unpredictability of human acts of choice, and insufficient knowledge about natural phenomena. Man does not know enough about natural phenomena to predict all their future deÂvelopments, and he cannot know the content of future human choices. All human choices are continually changing as a result of changing valuations and changing ideas about the most apÂpropriate means of arriving at ends. This does not mean, of course, that people do not try their best to estimate future developments. Indeed, any actor, when employing means, estimates that he will thus arrive at his desired goal. But he never has certain knowledge of the future. All his actions are of necessity speculations based on his judgment of the course of future events. The omnipresence of uncertainty introduces the ever-present possibility of error in human action. The actor may find, after he has completed his action, that the means have been inappropriate to the attainment of his end.
 Action as Exchange
Action is an attempt to exchange a less satisfactory state of affairs for a more satisfactory one. What gratifies less is abandoned in order to attain something that pleases more. The benefit of an action is its psychic revenue or profit. The next-best alternative, that is abandoned, is the price, its value is called the cost.
The exchange may be autistic, not involving another person, or it may be interpersonal. Interpersonal exchange is also called trade.
 Actors as individuals
Human action can be only undertaken by individual â€śactors.â€ť Only individuals have ends and can act to attain them. â€śSocietiesâ€ť or â€śgroupsâ€ť have no independent existÂence aside from the actions of their individual members. Thus, to say that â€śgovernmentsâ€ť act is merely a metaphor; actually, certain individuals are in a certain relationship with other inÂdividuals and act in a way that they and the other individuals recognize as â€śgovernmental.â€ť This does not mean that the collective institution itself has any reality apart from the acts of various individuals. Similarly, an individual may contract to act as an agent in representing another individual or on behalf of his family. Still, only individuals can desire and act. The existence of an institution such as government becomes meaningful only through the actions of those indiÂviduals who are and those who are not considered as members.
 What is not action
Human action is purposeful behavior, unlike those observed movements which, from the point of view of man, are not purposeful. These include all the observed movements of inorganic matter and purely reflexive types of human behavior, that are simply involuntary responses to certain stimuli. Human action, on the other hand, can be meaningfully interpreted by other men, for it is governed by a certain purpose that the actor has in view. The purpose of a manâ€™s act is his end; the desire to achieve this end is the manâ€™s motive for instituting the action.
All human beings act by virtue of their existence and their nature as human beings. We could not conceive of human beings who do not act purposefully, who have no ends in view that they desire and attempt to attain. Things that did not act, that did not behave purposefully, would no longer be classified as human.
- Ludwig von Mises. "1. Purposeful Action and Animal Reaction", Chapter 1. Acting Man, Human Action online edition, referenced 2009-05-01.
- Murray N. Rothbard. "Chapter 1-Fundamentals in Human Action", Man, Economy and State, online edition, referenced 2009-05-01.
- Ludwig von Mises "4. Action as an Exchange" Chapter IV. A first analysis of the category of Action, Human Action, online edition, referenced 2009-05-11.