Online research in philosophy

Many philosophers believe that 1) most uses of functional language in biology make implicit reference to natural selection and 2) the fundamental way in which biologists identify parts and processes in organisms is by their selected function(s). Both these claims are mistaken. Much functional language in biology refers to actual causal roles, and if this were not so, biology would be impossible. The extensive biological literature on the ‘character concept’ focuses on another principle of biological identity, namely homology. I outline some of this work and use it to refute philosophical arguments for the importance and ubiquity of classification by adaptive function.

This paper reviews the debate on the notion of biological function and on functional explanation as this takes place in philosophy. It describes the different perspectives, issues, intuitions, theories and arguments that have emerged. The author shows that the debate has been too heavily influenced by the concerns of a naturalistic philosophy of mind and argues that in order to improve our understanding of biology the attention should be shifted from the study of intuitions to the study of the actual practice of biological inquiry.

In the biological realm, a complete explanation of a trait seems to include an explanation in terms of function. It is natural to ask of some trait, "What is its function?" or "What purpose in the organism does the particular trait serve?" or "What is the goal of its activity?" There are several views concerning the appropriate definition of function for biological matters. Two popular views of function with respect to living things are Cummins' organizational account and the Griffiths/Godfrey-Smith modern history account. Whereas Cummins argues that a trait functions so as to contribute to the general organization of some organism's present structure, Griffiths, and Godfrey-Smith argue that a trait functions because of its fitness with respect to the organism's recent evolutionary history. In this paper, I show how these accounts can be made compatible and compliment one another. Given that structure, organization, operational flexibility, function, and evolutionary history are all factors to be considered in an organism's makeup, we should expect that the traits of an organism function the way they do because such traits presently contribute to the overall organization of the organism (Cummins) as well as were selected for in the organism's species' recent ancestry (Griffiths/Godfrey-Smith).

According to historical theories of biological function, a trait's function is determined by natural selection in the past. I argue that, in addition to historical functions, ahistorical functions ought to be recognized. I propose a theory of biological function which accommodates both. The function of a trait is the way it contributes to fitness and fitness can only be determined relative to a selective regime. Therefore, the function of a trait can only be specified relative to a selective regime. Apart from its desirable pluralism, only this view of relational function can support the function/accident and function/malfunction distinctions commonly thought to be part of the concept of function. Furthermore, only relational function correctly characterizes the explanatory consequences of function attributions in evolutionary biology.

Neo-teleology is the two part thesis that, e.g., (i) we have hearts because of what hearts are for: Hearts are for blood circulation, not the production of a pulse, so hearts are there--animals have them--because their function is to circulate the blood, and (ii) that (i) is explained by natural selection: traits spread through populations because of their functions. This paper attacks this popular doctrine. The presence of a biological trait or structure is not explained by appeal to its function. To suppose otherwise is to trivialize natural selection.

I argue that there are at least four different ways in which the term ‘function’ is used in connection with the study of living organisms, namely: (1) function as (mere) activity, (2) function as biological role, (3) function as biological advantage, and (4) function as selected effect. Notion (1) refers to what an item does by itself; (2) refers to the contribution of an item or activity to a complex activity or capacity of an organism; (3) refers to the value for the organism of an item having a certain character rather than another; (4) refers to the way in which a trait acquired and has maintained its current share in the population. The recognition of a separate notion of function as biological advantage solves the problem of the indeterminate reference situation that has been raised against a counterfactual analysis of function, and emphasizes the importance of counterfactual comparison in the explanatory practice of organismal biology. This reveals a neglected problem in the philosophy of biology, namely that of accounting for the insights provided.

Philosophers of evolutionary biology favor the so-called etiological concept of function according to which the function of a trait is its evolutionary purpose, defined as the effect for which that trait was favored by natural selection. We term this the selected effect (SE) analysis of function. An alternative account of function was introduced by Robert Cummins in a non-evolutionary and non-purposive context. Cummins''s account has received attention but little support from philosophers of biology. This paper will show that a similar non-purposive concept of function, which we term causal role (CR) function, is crucial to certain research programs in evolutionary biology, and that philosophical criticisms of Cummins''s concept are ineffective in this scientific context. Specifically, we demonstrate that CR functions are a vital and ineliminable part of research in comparative and functional anatomy, and that biological categories used by anatomists are not defined by the application of SE functional analysis. Causal role functions are non-historically defined, but may themselves be used in an historical analysis. Furthermore, we show that a philosophical insistence on the primary of SE functions places practicing biologists in an untenable position, as such functions can rarely be demonstrated (in contrast to CR functions). Biologists who study the form and function of organismal design recognize that it is virtually impossible to identify the past action of selection on any particular structure retrospectively, a requirement for recognizing SE functions.

But what are functions? Here, 15 leading scholars of philosophy of psychology and philosophy of biology present new essays on functions.