The meaning of function statements is not clear. Several authors have come up with different explications. By interviewing biologists I tried to get a picture of how they think about function. Two explications of Feature X of organism S has function F came to the fore: (1) X contributes to F and F contributes to survival/reproduction of S and (2) X does F and that contributes to the evolutionary development of X in S via natural selection. Most biologists also related (...) function to adaptation. Gould and Vrba criticize the ordinary use of adaptation in biology. They propose to use it only in the sense of features developed by natural selection for their current role and to use exaptation for features enhancing fitness, but not developed for this by natural selection. This, however, leaves a terminological gap, because as a consequence only effects of adaptations are functions. Effects of exaptations and effects which are not beneficial, like the production of heart sounds, are placed on the same level. That is not in accordance with the practice of biology. That is why a distinction is made between general, adaptive and exaptive functions: function as a pluralistic concept. (shrink)

Michael Ruse [3] has criticized the distinction between biological function and evolutionary adaptation that I argued for in my article “Biological Adaptation” [2]. I shall show below that Ruse's criticisms are not, for the most part, well taken and that the distinction remains as I made it.

The prevalence of optimality models in the literature of evolutionary biology is testimony to their popularity and importance. Evolutionary biologist R. C. Lewontin, whose criticisms of optimality models are considered here, reflects that "optimality arguments have become extremely popular in the last fifteen years, and at present represent the dominant mode of thought." Although optimality models have received little attention in the philosophical literature, these models are very interesting from a philosophical point of view. As will be argued, optimality models (...) are central to evolutionary thought, yet they are not readily accomodated by the traditional view of scientific theories. According to the traditional view, we would expect optimality models to employ general, empirical laws of nature, but they do not. Fortunately, the semantic view of scientific theories, a recent alternative to the traditional view, more readily accomodates optimality models. As we would expect on the semantic view, optimality models can be construed as specifications of ideal systems. These specifications may be used to describe empirical systems--that is, the specifications may have empirical instances. But the specifications are not empirical claims, much less general, empirical laws. Although philosophers have yet to discuss the general features and uses of optimality models, these topics have stimulated much recent discussion among evolutionary biologists. Their discussions raise a number of precautions concerning the proper use of optimality models. Moreover, many of their caveats can be interpreted as general reminders that 1) optimality models specify ideal systems whose empirical instantiations may be quite restricted, and that 2) optimality models should not be construed as general, empirical laws. As G. F. Oster and E. O. Wilson caution, "the prudent course is to regard optimality models as provisional guides to further empirical research and not necessarily as the key to deeper laws of nature." It seems, then, that the semantic view of theories is more sensitive to the nature and limitations of optimality models than is the more traditional view of theories. (shrink)

The theory of evolution by natural selection is, perhaps, the crowning intellectual achievement of the biological sciences. There is, however, considerable debate about which entity or entities are selected and what it is that fits them for that role. This article aims to clarify what is at issue in these debates by identifying four distinct, though often confused, concerns and then identifying how the debates on what constitute the units of selection depend to a significant degree on which of these (...) four questions a thinker regards as central. (shrink)

In successive issues of this journal Ronald Munson [2] and I [4] have made, quite independently, conflicting claims about the relationship between biological adaptation and biological function. I state, admittedly without proof, that “a functional statement in biology draws attention to the fact that what is under consideration is an adaptation or something which confers an ‘adaptive advantage’ on its possessor”. This was an identity claim. Munson claims, with proof, that “adaptation and function are not identical”. In this discussion note (...) I want to examine the three arguments Munson gives in support of his claim, and I shall try to show that they do not hold. (shrink)

I analyse some of the key evolutionary issues that arise in the study of consciousness from a bio-philosophical point of view. They all seem to be related to the fact that phenomenality has a special status: it is a very complex feature, apparently more than biological, it is hard to define because of the plurality of its displays and it is difficult to study with classic evolutionary tools. Giving an answer to the question “is consciousness an adaptive trait?” thus seems (...) to be very difficult and this paper intends to sketch some of the problems we should be concerned with when studying phenomenality as an adaptation. (shrink)