THREE ACCOUNTS

Talk of functions looms large in discussions of teleology. The concern has been mainly with statements of the form “the (or a) function of x is to y,” e.g., “the function of the heart is to pump the blood.” In recent years analyses of such statements tend to fall into three general categories.

Some specify what this good is, others do not. According to Sorabji, there is a sense of “function” for which a necessary condition is that “the performance by a thing of its (putative) function should confer some good” (1964, p. 291).^[XCII] But the goods can vary and particular ones should not be specified as part of an analysis. Woodfield has a similar account. Hempel and Ruse, on the other hand, identify specific goods, adequate

working order for the former, survival and reproduction for the latter. According to Hempel, a function of x in a system S is to y if and only if x does y and x’s doing y ensures the satisfaction of certain conditions necessary for S’s remaining in adequate, effective, or proper working or­der. For Ruse, the function of x in S is to y if and only if S does y by using x and y aids in the survival and reproduction of S.

In what follows I shall formulate the doctrine in a general way without mentioning specific goods, although this can be done to obtain particular versions.

The Good-Consequence Doctrine: The (a) function of x (in S) is to y if and only if x does y (in S) and doing y (in S) confers some good (upon S, or perhaps upon something associated with S, e.g., its user in the case of artifacts).

Thus we can say that the function of the heart in mammals is to pump the blood because the heart does pump the blood in mammals and pumping blood confers a good upon mammals. But we cannot say that the function of a poison ivy reaction in humans is to make the skin itch, since the latter confers no good upon humans.

The second doctrine focuses upon the idea of contributing to a goal that something or someone has.

The Goal Doctrine: The (a) function of x (in S) is to y if and only if x does y (in S) and doing y (in S) is or contributes to some goal which x (or S) has, or which the user, owner, or designer of x (or S) has.

For example, a function of my hands is to grasp objects, because my hands do this, and grasping objects is, or at least contributes to, one of the goals which I, their user, have. An appeal may be made here to the notion of a goal-directed system, roughly, a system which persists in or tends to achieve some state (the goal) under a variety of disturbing conditions. Those who speak this way would say that the function of the thermostat in a home heating system is to turn the heat on and off, since doing so contributes to a “goal” of the heating system, namely, to maintain a constant tempera­ture. Anyone who refuses to attribute goals to inanimate objects can still espouse the present doctrine, provided that he attributes the goal to an animate user, owner, or designer of the object or system.

Although so far as I know no one has formulated the doctrine in ex­actly this way, a goal doctrine is suggested by Nagel (1961), as well as more recently by Boorse (1976).^[93] According to both authors, in the case of items such as guided missiles the goals are to be attributed to the arti­facts themselves; with items such as chairs and fountain pens, according to Boorse at least, the goal is to be attributed to a “system” consisting of the artifact together with its user (1976, p. 70). In general, however, nei­ther writer would attribute the goal simply to the user or to the designer of the artifact, as my more general formulation permits.

The good-consequence and goal doctrines are quite broad, as I have stated them, and the question of their logical independence might be raised. Specific forms of one doctrine can be independent of either spe­cific or general forms of the other. Something may contribute to a goal that I have even though it does not increase my chances of survival and reproduction (Ruse's specific good); and something may increase my chances of survival and reproduction even though survival and reproduc­tion is not, and fails to contribute to, any goal of mine (e.g., my goal is to die quickly and without descendants). Again a good consequence theorist might refuse to attribute goals to anything but humans and higher animals while nevertheless claiming that various activities can confer a good upon things in addition to humans and higher animals. (Soaking up rainwater is beneficial for plants, he might say, even though it does not contribute to any of their goals, since they have none.)

On the other hand, if we consider these two doctrines in their most gen­eral formulations and include an appeal to goal-directed systems, to goods and goals not just for S but for users, owners, and designers of S, and to cases in which doing y either is or contributes to a goal, then the doctrines may well not be independent. It is difficult to imagine a case in which doing y confers a good upon S (or upon its user, owner, or designer) but is not and does not contribute to any goal of S (or its user, etc.), or vice versa.

A third position, the explanation doctrine, which has been defended by Wright (1973, 1976), Ayala (1970), Bennett (1976), and Levin (1976), seems quite different from the other two. The general idea is that function statements provide etiological explanations of the existence or presence of the item with the function. Since Wright's account is simple and gen­eral I will use it in what follows.

The Explanation Doctrine: The function of x is to y if and only if x is there because it does y (this “because” involves the idea of etiological explanation which Wright understands may include causes and agent's reasons); and y is a consequence of x s being there.

For example, the function of that switch is to turn the light on and off since the presence of that switch in this room is etiologically explainable by reference to the fact that it turns the light on and off, and its doing this is a consequence of its being there. When it comes to natural functions Wright invokes the ideas of natural selection and heredity. The function of the human heart is to pump the blood since the heart’s presence in hu­mans can be explained, via natural selection and heredity, by the fact that it does pump the blood. (Nature selected in favor of those who get their blood pumped by means of the heart.) And the blood’s being pumped is a consequence of the heart’s presence. Although it will often be the case, it is not required by this analysis that xs doing y confer some good or contribute to some goal of anyone or anything.

The goal and explanation doctrines are meant to apply to the functions of artifacts as well as natural objects and processes. Their proponents ad­vocate a unified analysis. By contrast, some good-consequence theorists, e.g., Ruse, restrict their particular versions of this doctrine to the functions of natural items only, while others, such as Hempel, believe that their doc­trine holds generally for all items to which functions are ascribed.

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