The common folk notion of an altruistic act is one that costs the acting agent while benefiting someone else. The arch-typical example is someone jumping into a raging torrent, at considerable (possibly fatal) risk to himself, in order to save a drowning stranger. But upon further consideration, the matter becomes far from simple.
The word "altruism" was coined by Auguste Comte(1), in order to describe the ethical doctrine he supported. He believed that individuals had a moral obligation to renounce self-interest and live for others. But the sentiment for which Comte coined the word has been around since the dawn of Western philosophy. Aristotle(2) wrote that men should love others more than themselves, and that the more one acts for another's sake, the better off one is.
This belief has permeated modern philosophical thinking on morality. C.D. Broad characterizes altruism as "the doctrine that each of us has a special obligation to benefit others."(3) W.G. Maclagan considers altruism "a duty to relieve the distress and promote the happiness of our fellows...Altruism is to...maintain quite simply that a man may and should discount altogether his own pleasure or happiness as such when he is deciding what course of action to pursue."(4) James Fieser states the altruist dictum as "An action is morally right if the consequences of that action are more favorable than unfavorable to everyone except the agent."(5) B.A.O. Williams is a little bit more inclusive, defining altruism as referring "to a general disposition to regard the interests of others, merely as such, as making some claim on one, and, in particular, as implying the possibility of limiting one's own projects."(6)
The MacMillan Online Dictionary defines altruism as "a way of thinking or behaving that shows you care about other people and their interests more than you care about yourself". The Mirriam-Webster Online Dictionary offers the definition as "unselfish regard for or devotion to the welfare of others; behavior by an animal that is not beneficial to or may be harmful to itself but that benefits others of its species." The Online Dictionary of Philosophical Terms and Names defines altruism as a "belief that an agent's moral decisions should be guided by consideration for the interests and well-being of other people rather than merely by self-interest, as egoism would recommend." And the Cambridge Online Dictionary says altruism is a "willingness to do things which bring advantages to other people, even if it results in disadvantage for yourself."
So it seems that in the common usage documented by these dictionaries, and discussed in the philosophical literature on Ethics, the concept of an altruistic act can vary quite widely. An act can be classed as altruistic if it results from your thinking of others and their interests as more important than you and your interests, regardless of the consequences of the act. Or an act can be classed as altruistic if it costs you and benefits others. That is quite a wide scope for disagreement and confusion.
We can, however, bring some analysis to the confusion. Firstly, the actual usage of the term can be divided neatly into two separate concepts. There is what I will call "evolutionary altruism" (hereafter "e-altruism"), also sometimes called "biological altruism", or "scientific altruism". And there is what I will call "psychological altruism" (hereafter "p-altruism"), also sometimes called "philosophical altruism".
P-altruism, is a very loosely circumscribed concept. While benevolence, compassion, and humanity were not major virtues for the ancient philosophers, modern moral philosophers generally agree that p-altruism is important to morality, although they disagree about what it is, how to explain it, and what its scope should be. A minimal appreciation, one favoured by many philosophers (notably Williams), is a recognition that the interests of others make claims on us and limit what we may do. There are two different dimensions that will help understand where the vagueness lies.
The first dimension is the matter of what things are covered by the concept. Some philosophers employ the concept only as applicable to actions that have moral consequences. Comte, Broad and Feiser would fall into this group. Other philosophers employ the concept only as applicable to intentions or motivations, regarding the intention/motivation of the agent as altruistic whether or not the intention is ever realized into action, or the action delivers the intended consequences. Maclagan and Williams would be an example of this position. And there are many philosophers who maintain positions somewhere between the two extremes.
The second dimension is the matter of benefits. Everyone agrees that an altruistic act must benefit another party besides the acting agent. But at one end of the spectrum, Kant for example, says that a moral act must be motivated by duty and not by any self-interest. So he would dismiss any action or intention that has any element of self-interest in its motivation. At the other end are philosophers who accept that any act that delivers benefits to another party is altruistic whether or not it is motivated by self-interest, or delivers benefits to the agent. So Williams, as an example, would class an act as altruistic as long as the agent fully considers the interests of others in his deliberations, regardless of how self-interested might be the motivation or the benefits that result. In between are positions that treat the idea of some cost to the agent as necessary for an act to be classed as altruistic.
In comparison to the rather vaguely defined notion of p-altruism, e-altruism is a very tightly defined concept. Unlike most notions of p-altruism, e-altruism is entirely based on a scientific examination of actual behaviors. In evolutionary biology, an organism is said to behave altruistically when its behaviour benefits other organisms, at a cost to itself. The costs and benefits are measured in terms of reproductive fitness.(7) A behavior (not necessarily a consciously intended act by a conscious agent) is e-altruistic if and only if it benefits the inclusive fitness of some other animal (not necessarily of the same species as the agent) at a cost to the agent's own inclusive fitness. Since inclusive fitness is a tightly defined concept of population genetics, it renders e-altruism just as tightly defined. Inclusive fitness would encompass what are otherwise known as "kin altruism", "reciprocal altruism", and "cooperative altruism". By the definition of e-altruism, none of these behaviors would qualify as e-altruistic. A mother cat dying to save her kittens is not an altruistic act.
The problem of the loose notion of p-altruism is that is invites confusion in philosophical discourse. Consider the definition that Williams has put forward. In his "Egoism and Altruism" article, he essentially incorporates into his notion of "altruism" all the other-relating considerations that a prudent self-centered person would readily entertain. He leaves left for his notion of "egoism" only a very narrow-minded future-ignoring self-only notion that no self-described egoist would accept as a realistic characterization of "egoism". The result is that William's criticism of "egoism" carries no weight. He has defined out of existence his potential opponents.
So the best way of defining an altruistic act, is to employ a tightly defined notion that will clear away the confusion. And that definition is what I have called "e-altruism". P-altruism is just too vaguely defined, and too inviting of confusion and cross-talk.
Notes and References
(1) Wikipedia contributors, "Auguste Comte" in Wikipedia, The Free Encyclopedia, URL=<http://en.wikipedia.org/w/index.php?title=Auguste_Comte&oldid=479561080>.
The Nicomachean Ethics, Translated
and introduced by David Ross, revised by J.L. Ackrill and J.O. Urmson;
Oxford University Press,
(3) Cheney, D. R. (Ed), Broad's Critical Essays in Moral Philosophy, Allen & Unwin, London, pp. 283--301).
(4) Maclagan, W.G., "Self and Others: A Defense of Altruism" in The Philosophical Quarterly, Vol 4, No 15 (Apr 1954): pp 109--127.
(5) Feiser, James, "Ethics" in The Internet Encyclopedia of Philosophy, URL=<http://www.iep.utm.edu/ethics/>.
(6) Williams, B.A.O.; "Egoism and Altruism" in his Problems of Self: Philosophical Papers 1956-1972. (Cambridge: Cambridge University Press, 1973).
(7) Okasha, Samir, "Biological Altruism" in The Stanford Encyclopedia of Philosophy, Edward N. Zalta (ed.), URL=<http://plato.stanford.edu/archives/win2009/entries/altruism-biological/>.