Reality: Fundamental Topics is Metaphysics

Chapter XII: Purpose

I That people and other conscious beings have purposes when they do things is not seriously contestable. this is one of the distinctive features of mental life as we know it. We act often with an end or goal in view; we conceive of (or imagine) something we desire or strive to bring it about, and succeed or not depending on the case (our abilities, the realizability of the goal, interfering circumstances). So there are purposes in the world. they are best understood by reference to states of imaginative or conceptual consciousness trained on the future. it seems plausible to suppose that such goal-directedness is a much more elaborate and sophisticated variety of features of systems, living and non-living, where no attribution of consciousness or intelligence would be made. in some such cases the system was designed by intelligent beings, ourselves, to be goal-directed (heat-seeking missiles, for example), so this is just our purposiveness at one remove. in other cases natural systems not designed by conscious and intelligent beings exhibit traits that resemble goal-directedness or purposiveness. An earlier age of philosophy— supremely exemplified in the Christian thirteenth century—sought to make a case from this widely evident phenomenon for belief in an overall guiding and creative hand for the world. Contemporary inquiry tends to take an approach that wholly reverses that earlier one: rather than see apparent purposiveness in intelligent nature as pointing to unseen high intelligence behind phenomena, modern naturalist investigation seeks to show that our C H A P t e R X i i Purpose 194 ReALitY: Fundamental topics in Metaphysics purposiveness derives from and resembles completely unintelligent and automatic mechanisms of the world—variations on the theme of the flower that opens its petals to the sunlight, not because it wants to or because someone wants it to, but because the warmth of the sunlight triggers the possibility of its absorbing the wherewithal for its survival. there are two problems regarding purpose that have not been wholly solved and which deserve consideration within metaphysics. One is a technical topic, and the other is anything but technical. Both were introduced to philosophy by the ancient Greeks. the more technical problem of purpose stems almost entirely from the thought of Aristotle. in assigning teleological themes to him i am not primarily concerned with historical or textual accuracy, although i think the views i discuss fit both history and texts. Aristotle or “Aristotle,” an imaginary philosopher who really held the views i shall assign to Aristotle, held that objects have ends, telea, as part of their nature: there is for every object an end or purpose for that object. Aristotle also held this to be true of activities or states of various kinds. it is natural to think that Aristotle has been guilty of a bad inductive inference in attributing to all objects a trait which only applies—and only can apply—to some of them, namely the implements or artefacts, objects, that have been made by intelligent beings precisely in order to fulfil some purpose that those intelligent beings had. For example, the purpose or end—the what-it-is-for—of a lawn mower is to cut grass, because that is what people made them for. the lawn mower has that telos derivatively: it has that purpose only because we have that purpose. Aristotle’s idea, however, seems more plausible than this. Just as machines and artefacts have purposes even though they are unthinking, so we attribute purposes to bodily organs and other inanimate parts of nature. in these latter cases—unlike lawn mowers—there is no intelligent being (apart, at any rate, from a God, if there were one) whose purpose it is that these objects have the purposes which we assign to them and which many say they objectively possess. the purpose or function of the heart is to pump blood and that of the liver is to secrete bile, while the colouration of animals serves to camouflage them from predators, and so on. Aristotle seems to have generalized from certain living systems or constituent parts of them. He comes to the idea of an objective, “natural,” creator-independent what-it-is-for for all individual living substances, and possibly also for non-living ones. this is an idea hard to even grasp, much less submit to the tribunals of evidence. A lawn mower, sure; a kidney, acceptably so. in that former case, as we have said, its telos derives...