Philosophy of Evolutionary Biology

Volume I

Stefan Linquist, Stefan Linquist

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781351911351
• Edition: 1
• Topic: Philosophie
• Subtopic: Geschichte & Theorie der Philosophie

The impact of evolutionary theory on the philosophy of science has been no less profound than its impact on the science of biology itself. Advances in this theory provide a rich set of examples for thinking about the nature of scientific explanation and the structure of science. Many of the developments in our understanding of evolution resulted from contributions by both philosophers and biologists engaging over theoretical questions of mutual interest. This volume traces some of the most influential exchanges in this field over the last few decades. Focal topics include the nature of biological functions, adaptationism as an explanatory and methodological doctrine, the levels of selection debate, the concepts of fitness and drift, and the relationship of evolutionary to developmental biology.

Part I
Function and Purpose in Biology

[1]
FUNCTIONS AS SELECTED EFFECTS: THE CONCEPTUAL ANALYST’S DEFENSE*

KAREN NEANDER†
Department of Philosophy Australian National University

In this paper I defend an etiological theory of biological functions (according to which the proper function of a trait is the effect for which it was selected by natural selection) against three objections which have been influential. I argue, contrary to Millikan, that it is wrong to base our defense of the theory on a rejection of conceptual analysis, for conceptual analysis does have an important role in philosophy of science. I also argue that biology requires a normative notion of a “proper function”, and that a normative notion is not ahistorical.

1. Introduction. This paper defends the etiological theory of proper functions, according to which, roughly speaking, biological proper functions are effects for which traits were selected by natural selection.¹ According to this theory, for instance, hearts have the proper function of pumping blood, because pumping blood is what hearts did that caused them to be favored by natural selection. This theory is now familiar enough (indeed it is fast becoming the consensus) but while it is mostly accepted that something of the sort happens to capture the actual reference class, the theory has been rejected as conceptual analysis. It is only because conceptual analysis itself has plummeted in the popularity stakes that the popularity of the etiological theory has, inversely, been allowed to rise. It is this to which I object.

The supposedly problematic feature of the etiological theory as conceptual analysis is that (true to its name) it makes a trait’s function depend on its history, more specifically (and supposedly worse) on its evolutionary history. There are three standard objections to this which I will mention now and discuss later, (i) It seems blatantly inaccurate historically. When Harvey announced the function of the heart in 1616 he knew nothing of Darwin’s theory, and so he clearly didn’t mean, or have in mind, that the circulation of blood was the effect for which hearts were selected by natural selection (Wright 1976, 97; Boorse 1976, 74; Nagel 1977, 284). (ii) Defining the notion of a “proper function” in terms of natural selection begs empirical and theological questions, and is “analytically arrogant” because it would seem “…to suggest that it is impossible by the very nature of the concepts—logically impossible—that organismic structures and processes get their functions by the conscious intervention (design) of a Divine Creator” (Wright 1976, 96–97. See also Boorse 1976, 74; and Bigelow and Pargetter 1987, 188.) (iii) It is strongly counterintuitive that a creature which lacked a history would thereby lack functions. Suppose we discovered that the whole lion species freakishly coalesced into existence one day, without evolution or design of any kind, “by an unparalleled saltation” (Boorse 1976, 74). Or consider “… the possible world identical to this one in all matters of laws and particular matters of fact, except that it came into existence by chance (or without cause) five minutes ago” (Bigelow and Pargetter 1987, 188). Surely, we can correctly ascribe biological functions to any such complex, intricately integrated organisms, despite their lack of history and their accidental genesis. Or so the argument goes.

Ruth Millikan has defended an etiological theory of proper functions from these objections (1989). However, she does so by turning her back on conceptual analysis. In her view, to use her own rhetoric, conceptual analysis is “…a confused program, a philosophical chimera, a squaring of the circle, the misconceived child of a mistaken view of the nature of language and thought” (1989, 290).² Millikan argues that the standard objections to the etiological theory are thus undermined by the fact that they presuppose that our task is conceptual analysis.

While Millikan’s defense throws into stark relief our need to be clear about our analytic aims, I believe it is wrong to base our defense of the etiological theory on a rejection of conceptual analysis. In my view, the sins of conceptual analysis do not measure large enough for it to be discounted as a witness in this case. Moreover, if we are clear about our analytic aims, we can confront head-on these standard objections and successfully defend the etiological theory as conceptual analysis. Toward this, I have found it useful to follow Millikan in making a distinction between conceptual analysis and something she calls “theoretical definition”. The first section of this paper begins with a discussion of this meta-analytic distinction, and explains why I believe conceptual analysis cannot be disregarded. Following this, I elaborate on the etiological theory being defended and then consider each of the standard objections in turn.

2. Conceptual Analysis or Theoretical Definition, or Both? The difference between conceptual analysis and theoretical definition is hard to state in uncontroversial terms, but the basic gist of the difference, as I will be using this meta-analytic distinction in this paper, is as follows.

Conceptual analysis is an attempt to describe certain features of the relationship between utterances of the term under analysis, and the beliefs, ideas, and perceptions of those who do the uttering. It involves trying to describe the criteria of application that the members of the linguistic community generally have (implicitly or explicitly) in mind when they use the term. In contrast, a theoretical definition is an attempt to explain some aspect of the thing referred to, or some aspect of the relationship between utterances of the term and the actual world. Which particular aspect depends on one’s semantic theory and on what one thinks is most central for semantic theory. Millikan argues (this is a crude rendition) that a theoretical definition should describe what a term refers to that explains the use of the term and why the term has survived and continued to be used (1984). She also suggests that theoretical definitions should describe the underlying phenomenon that explains the surface analogies by which we have recognized that things are things of a kind (1989, 293). Thus “water is a liquid with the molecular structure HOH” and “gold is the element with the atomic number 79” are theoretical definitions. (Liquid HOH is the underlying phenomenon to which we usefully refer, and it also explains water’s opacity, its thirst quenching powers, and so on.)

Some would add two further features, which I have purposely omitted, to my characterization of conceptual analysis. They would add that conceptual analysis is thought to constitute a search for meaning, and that it is a search for necessary and sufficient conditions for the application of the term under analysis. Add these, and I too will probably abandon ship. Since Millikan includes these features in her characterization of conceptual analysis (1989, 290) some of our disagreement may be merely verbal. However, her defense of the etiological theory requires us to reject conceptual analysis as I have more weakly characterized it, and my weaker characterization describes an analytic exercise that is more readily defended.

Dispute over whether conceptual analysis or theoretical definition best captures meaning (properly so called) may be largely responsible for the rejection of conceptual analysis. So let me concede a point or two. It may be that meanings are not inside people’s heads, not wholly, and perhaps not even partly. And since conceptual analysis is an attempt to understand what goes on inside speakers’ heads—in that it is a search for the criteria of application that people generally have in mind—it may be that, if we are searching for meaning, conceptual analysis is a confused approach. But we might be interested in something other than, or in addition to, meaning. So let us define “conceptual analysis” as a search for the criteria of application that people generally have in mind when they use the term under analysis, and discuss the merits of such a search, leaving the issue of meaning aside. Perhaps attempting to understand how biologists implicitly understand the notion of a “proper function” can be fruitful, whether or not this gives us the meaning of the term.

Conceptual analysis has also often been associated with a search for necessary and sufficient conditions, and the idea that such conditions are required has long been disreputable. But such a requirement is no more inherent to the aims of conceptual analysis than it is to the aims of theoretical definition. The criteria of application that the relevant linguistic community generally has in mind might be better expressed in terms of a family resemblance, similarity to prototypes, or Minskian frames.³ Indeed, necessary and sufficient conditions are probably more likely to be found for theoretical definitions (consider those given for “water” and “gold”).

Admittedly, the criteria of application that people actually use are often vague, shifting, highly context-sensitive, highly variable between individuals, and often involve perceptual data of a kind that is inaccessible, at least to philosophical methods. This is certainly daunting. But it does not follow that we cannot discover anything useful about these criteria of application. Conceptual analysts can describe those criteria of application that people standardly apply, most of the time, in the most standard contexts. Also, when the relevant linguistic community consists of specialists, and the term under analysis is one of their specialist terms, and is also abstract (nonperceptual) and embedded in well-articulated theory, the severity of each of these factors will be greatly reduced. Since this is the case for contemporary biologists and their notion of a “proper function”, we have more reason to expect success in this case than in most.⁴ The problems with conceptual analysis are many, but they amount to a need to concede that it will be rare, if ever, that a definitive, exhaustive and universal analysis can be given. This is not to say that some insight into relevant criteria of application cannot be achieved in many cases. Since philosophers seem to have been providing insights along these lines, stronger argument is needed to show that they cannot have been doing so.

Of course it would be futile trying to do conceptual analysis if we didn’t have any use for it; but we do. We need it to clarify thought and communication, which are the time-honored reasons for engaging in the activity. While this point epitomizes the unoriginal, we may need to remind ourselves that theoretical definition cannot entirely replace conceptual analysis in this respect. This point can be made most vividly with respect to nonreferring terms, but it also applies more generally.

Given that conceptual analysis is an attempt to describe what people think they are referring to, we can provide a conceptual analysis for “witch”, “entelechy” and “phlogiston” because we can explain what people thought witches, entelechies and phlogiston were. A theoretical definition, in contrast, is (roughly) an attempt to describe the things referred to, so where reference fails there is no theoretical definition. If we wanted to persuade a Medieval theologian that witches don’t exist, no theoretical definition could refine our understanding of his or her understanding of “witch”. Good communication and debate with this benighted individual demands that we know more than a theoretical definition can tell us (which is just that witches don’t exist). To successfully engage in debate we would need to know what precisely a witch was supposed to be. Admittedly, we are not likely to meet many theologians of this kind, but similar sorts of debates occur often enough in philosophy. For instance, to persuade us that there is no pain, Daniel Dennett once argued that our criteria of application are inconsistent (Dennett 1978). He engaged (as he must) in conceptual analysis to do this. Similar styles of argument can also be found regarding libertarian free-will, to give one other example.

Nor is theoretical definition independent of conceptual analysis, since the latter is required to delimit the scope of the former. Furthermore, when the relevant linguistic community is very well informed about what they speak of, we should expect conceptual analysis and theoretical definition to closely correspond. For example, while it was once false as conceptual analysis that water meant “liquid with the molecular structure HOH”, the criteria of application have changed and kept abreast with our knowledge. Now a conceptual analysis of water would have to include that water is HOH. I could be deceived into thinking that some other clear and thirst-quenching liquid was water. But if I learned that it was not HOH, I would then deny that it was water. So being HOH is now my criterion of water. Closer to the task at hand, if we were to offer a conceptual analysis of “water” as used by modern Western chemists we would certainly have to mention that the molecular structure HOH was a defining characteristic for them. Given that modern biologists are in possession of a fairly full and correct set of beliefs about biological proper functions (more so than we are anyway) it is highly likely that conceptual analysis and theoretical definition will closely correspond in this case too.

The moral for Millikan’s defense of the etiological theory is this: if the etiological theory is implausible as conceptual analysis, then it is thereby implausible as theoretical definition. We can gain no immunity from the standard objections to the etiological theory by insisting that we are only interested in theoretical definition. When the relevant linguistic community thoroughly understands the nature of what it speaks of, there is a strong prima facie case in favor of its having integrated this understanding into the basis of its linguistic competence. Our understanding of the world, and the conceptual framework we employ in talking about it, are virtually the same thing.

I see conceptual analysis and theoretical definition as complementary and interdependent, describing different but related aspects of language. In keeping with the views expressed in this section, the claims made in the next, where I explain the etiological theory in a little more detail, are intended to hold true from the standpoint of both theoretical definition and conceptual analysis. In later sections, the differences between these two modes of analysis are again the focus of attention, for different criticisms and justifications are appropriate depending on our analytic aims.

3. Proper Functions as Selected Effects. In biology, as well as in other contexts, the most explicit use of the notion of a “proper function” is in sentences that express function attributions, such as “It is normal for penguins to be myopic on land since the proper function of their optic lenses is sharp underwater vision”, or “A function of the hypothalamus is the monitoring of blood oxygen and sugar levels”. Such function attributions are also made regarding artifacts (the function of an armchair is to provide comfortable seating, the function of the carburetor is to mix fuel with air, and so on). Especially in biology, the notion of a proper function has other less obvious but essential roles that derive from these basic function attributions (more on this in the last section). However, these explicit function attributions are a natural place to start when we seek to understand the notion. The problem is to discover what exactly is attributed when we attribute a proper function (or more loosely a function) in sentences of the form “The/a proper function of X is Z”.

My claim is that the proper function of a trait is to do whatever it was selected for. In so far as our organismic structures and processes are the result of selection they are the resul...