Jakob Roloff

In this first part of a two-part response, we respond to Dong and Piccinini’s goal-contribution account (GCA) by arguing that it fails to adequately capture what makes something a function. As we see it, the core problem is that GCA ignores the role of past selection. Without reference to selection history, GCA struggles to distinguish functions from mere effects, especially in cases involving novel traits, dysfunction, or systemic breakdowns. We show that these challenges can be met by acknowledging the inescapability of past selection—even if we want to remain open to pluralist uses of “function” in science. In the end, we propose a new framework—the blueprint account—which integrates intuitions from causal role, organizational, and selection-based theories. While we may want to rethink how we talk about functions, we argue that any viable account will still need to take selection seriously.

In this first part of a two-part response, we defend the selected effects (SE) theory of biological function against recent critiques by Dong and Piccinini. Challenging the claim that SE theory cannot accommodate novel mutations or artifacts, the authors argue that selection is inescapable for understanding function. They show that even novel traits often emerge from lineages with established functions and that artifacts can be integrated into SE accounts via intentional design and derived functions. Ultimately, we conclude that no compelling reason has been given to abandon or rethink the selected effects approach.

Since the early debates on teleosemantics, there have been people objecting that teleosemantics cannot account for evolutionarily novel contents such as “democracy” (e.g., Peacocke in A Study of Concepts, MIT Press, Cambridge, 1992). Most recently, this objection was brought up by Garson (What Biological Functions Are and Why They Matter, Cambridge University Press, Cambridge, 2019.) and in a more moderate form by Garson and Papineau (Biol Philos 34(3):36, 2019.). The underlying criticism is that the traditional selected effects theory of functions on which teleosemantics is built is unable to ascribe new functions to the products of ontogenetic processes and thus unable to ascribe functions to new traits that appear during the lifetime of an individual organism. I will argue that this underlying thought rests on rather common misunderstandings of Millikan’s theory of proper functions, especially her notions of relational, adapted, and derived proper functions (Millikan in Language, Thought, and Other Biological Categories: New Foundations for Realism, MIT Press, Cambridge, 1984: Ch. 2). The notions of relational, adapted, and derived proper functions not only help us solve the problem of novel contents and can ascribe functions to the products of ontogenetic selection mechanisms but are indispensable parts of every selected effects theory.

Millikan’s (1984. Language, Thought, and Other Biological Categories: New Foundations for Realism. MIT Press) selected effects theory of functions states that functions are effects for which the ancestors of a trait were selected for. As the function is an effect a thing’s ancestors produced, only things that are reproductions in some sense can have functions. Against this reproduction requirement, Garson (2019. What Biological Functions Are and Why They Matter. Cambridge University Press) argues that not only processes of differential reproduction but also processes of differential persistence can lead to new functions. Since such “persistence functions” have the same explanatory power as traditional selected effects functions, selected effects theorists should include them in their theory. In this paper, I will defend Millikan’s theory against this argument. I will show that the proponents of the generalized theory have yet to provide a working notion of populations that avoids a liberality problem. Further, I will argue that persistence functions are at best a marginal case of functions due to their restricted explanatory power.

Donald Davidson’s causal theory of actions states that actions must be rationalized and caused by a belief-desire-pair. One problem of such a causal theory are cases of deviant causal chains. In these cases, the rationalized action is not caused in the right way but via a deviant causal chain. It therefore intuitively seems to be no action while all conditions of the causal theory are met. I argue that the problem of deviant causal chains can be solved by adding a teleofunctionalist condition. This condition requires that the belief-desire pair that rationalizes an action must cause that action in a selection-historically normal way. I try to show that this additional condition drops counterintuitive cases of deviant causal chains out of the class of actions while being flexible enough to classify such cases as actions in which causal detours are intuitively permissible.