FUNCTIONAL EXPLANATIONS
Do function sentences explain anything, and if so what? This question, I believe, is badly put since it is primarily people who explain by uttering words or sentences. Explaining is an illocutionary act—one typically performed by uttering words in certain contexts with appropriate intentions; and in my 1965 article I have suggested conditions required for its performance (see chapter 6 in this book).
Roughly, on my account, a person P explains q by uttering u if and only if P utters u with the intention that his utterance of u render q understandable by producing the recognition that u expresses a correct answer to a question Q which presupposes q. If we assume that any sentence of the form “P explains q by uttering u” is or is transformable into one in which q is an indirect question then Q is the direct form of that question. This does not mean that we cannot explain things such as events, but only that we do so by answering some question about them.Accordingly, we might ask: When one utters a function sentence what is one explaining? I.e., what does one intend to render understandable in the manner suggested here? To this the reply must be: not necessarily anything. If someone asks what organ's function it is to pump the blood, and I reply that it is the function of the heart to pump the blood, I need not be explaining anything at all but simply identifying an organ. (By analogy, if someone asks “who got sick because he ate spoiled meat?” and I reply “Jones got sick because he ate spoiled meat” I am not explaining why Jones got sick but simply identifying the unfortunate man.) I make this point here only because there are those who seem to think that when one utters a function sentence one is necessarily explaining something.[110]
Still it seems plausible to suppose that one can explain by uttering a function sentence, and if so the question is what.
A typical view among those who analyze functional explanations is that at most one thing is explained (though there is some disagreement over what this is). By contrast, I want to suggest that a number of different things can be explained by uttering function sentences; i.e., a number of different explanatory questions can be answered.Most simply, one can utter a function sentence in explaining what function x has. There is a lever on the dashboard of my car whose function puzzles people since when it is pulled nothing seems to happen. I explain its function to them by saying that its function is to open the reserve fuel tank.
One can also utter a function sentence in explaining the doing of y. The latter can be explained in various ways, i.e., on my view, by answering a number of different questions including
(1) How, i.e., by what means, is y done?
(1) can be answered by uttering a function sentence since in identifying x as an item whose function is to do y one identifies a means by which y is done. Some writers say that function sentences are used to provide causal explanations of y’s occurrence, i.e., that by uttering such sentences one can answer the question
(2) What causes (caused) y to occur?
No doubt in many cases when an answer to (1) is given by a function sentence an answer to (2) is easy to construct. If the reserve fuel tank is opened by means of that lever, than pulling the lever causes the reserve tank to open. But as indicated in section 6 a means by which y is done is not in general a cause of y’s being done. (1) and (2) are not identical questions, and if someone explains the doing of y by uttering a function sentence the question he is answering is (1), although his answer to (1) will often, but not always, contain sufficient information to enable the construction of an answer to (2).
Finally, as a number of writers have claimed, one can utter a function sentence in explaining %’s existence, continued existence, presence, location, use, and so forth.
Among the ways these can be explained is by answering the question(3) For what end does x exist (continue to exist, is x present, used, etc.)?
One should distinguish the teleological claim that x does something which serves an end from the stronger teleological claim that it exists (is present, is used, etc.) in order to serve that end. The sun does things which serve various ends, yet it does not exist in order to serve any of them. By contrast, artifacts exist by human design to serve certain ends. Bodily organs are generally regarded not merely as serving certain ends but as existing or being present in order to serve those ends. Since only in some cases is an end served by x an end for which x exists, an answer to (3) can be provided only by certain function statements, that is, by design, use, and those service function statements based on design or use. If x was designed (etc.) to serve as, or is used as, a means of doing y, then x exists (is present, is used) in order to serve the end of doing y. Service function statements based on the conferring of a good can also be used to answer (3) provided that, as with bodily organs, the x in such cases exists in order to do y. Thus it is possible to utter “the function of this lever is to open the reserve fuel tank” and “the function of the heart is to pump the blood” in explaining the existence of these items by answering a question of form (3). To bring out the fact that x in such cases not only serves an end but exists to serve an end one might formulate one's function sentence as “the function for which x exists is to do y.”
Some writers who say that function sentences can be used to explain x’s existence, presence, and so on believe that such explanations are causal (in the sense of efficient rather than final causation), i.e., that they answer a question such as
(4) What causes x to exist (be present, etc.)?
On this view the answer function sentences provide is that what causes x to exist is the fact that x does y.
Against this Robert Cummins (1975) correctly argues that function sentences cannot in general be used to provide causal explanations of x’s existence. My heart was not caused to exist by the fact that it pumps my blood. Cummins, however, mistakenly concludes from this that at least in the case of nonartifacts, function sentences cannot be used to explain x’s existence or presence. What he overlooks is that one can explain x’s existence or presence by answering a question such as (3) in a way that is not causal.The child who asks why he has a heart or why hearts are present in humans may simply want to know a function for which they exist, in this case, what benefit to the body is accomplished by means of the heart for which it exists. He is not or need not be asking a causal or etiological question about how a heart came to be present in humans, what causes it to remain present in the human species, or to be where it is in the body. Similarly if the earth doctor dissects a Martian's body and discovers an organ different from any he knows, he might ask: “Why do Martians have that organ?” In asking this question he may not want to know how Martians came to have that organ but simply for what end it exists.
To this it might be replied that the doing of y is an end for which x exists only if it is a cause of xs existence. But this cannot be right. It is not the opening of the reserve fuel tank which causes this lever to exist, but rather the actions of certain agents (who may have designed the lever or placed it where it is to serve that end). Accordingly, a second reply might be that the doing of y is an end for which x exists only if there is some act or event in which the doing of y is an end where that act or event caused x to exist. Opening the reserve fuel tank is an end for which this lever exists only if agents who designed or positioned the lever to serve that end acted in certain ways. Pumping the blood is an end for which the heart exists, it might be said, only if nature acts in such a way as to select in favor of those in whom the benefit of pumping the blood is achieved by means of the heart.
Furthermore, to establish that doing y is an end for which x exists we must discover what caused x to exist or at least make certain causal assumptions.The validity of this second reply need not be discussed, since even if it is accepted the point I am trying to make is not vitiated. (3) and (4) are different questions, and an answer to (3) is not, and need not contain, an answer to (4). An answer to (3) may contain the information that the doing of y is an end for which x exists without identifying any act or event that caused x to exist, and this is so even if in order to establish the correctness of this answer one must be able to identify or make some assumption about such an act or event. To be sure, having received an answer to a question of form (3) one is often in a position to construct at least some answer to (4). If I am informed that the function for which this lever exists is to open the reserve fuel tank, then knowing that it is an artifact I know that it was some action of an agent that caused it to be present. But if I get much more specific I risk the danger of falsehood. For example, if I assume that it was designed by its designer to serve that end, I may be making a mistake (as in the car bolt example of section 4). Moreover, some answers to a question of form (3) may not put one in a position to answer every or any form of (4). One who is ignorant of the doctrines of natural selection and heredity may be informed about the function of that strange organ in the Martian body and yet be unable to causally explain how the organ came into existence or to say what, if anything, causes it to remain or to exist where it does.
Contemporary philosophers of science tend to adopt the view that to explain %’s existence or presence is to cite a cause or causes. Within this tradition opinion then divides over functional explanations. On the one hand there are those who say that function sentences can be used to explain %’s existence because they cite causes; on the other hand there are those who deny that function sentences provide causes for, and hence can be used to explain, %’s existence. By contrast, I have been defending a position within a more ancient tradition, the Aristotelian, according to which one can explain %’s existence—one can explain why % exists, why % is present, why S’s have %—not only by answering a question of form (4) but by answering one of form (3), even if an answer to the latter does not contain an answer to the former.