Fabian Hundertmark, Bielefeld University
Jakob Roloff, Justus-Liebig-University Gießen
Francesca Bellazzi, University of Oslo, ERC Project Assembling Life (no.101089326)
1. Introduction
Functions are everywhere. Coffee machines have the function of making our coffee and our hearts have the function of pumping our blood. But what are functions, and how should we think of them – or rather re-think them?
Broadly defined, functions are special causal contributions that can inform us of an entity’s identity, history, and role in a system. To use a classic example, consider the heart. The heart is a muscle with the function of pumping blood, and this function informs us about what the heart is, why it has developed, and what it contributes to a given system. While there are many accounts of functions, many philosophers of biology have argued for a selected effect view (SE) of functions (Neander, 1983; Millikan, 1984). According to this view, the function of a trait is an activity of such a trait that has been evolutionarily selected for because it conferred some fitness advantage on members of the population having that trait. In the example, the heart has the function of pumping blood because it was selected for on the basis of the fitness advantages of those with a pumping heart, which allowed them to reproduce more effectively in a given environment.
The SE view has a series of advantages. It accounts for why function ascriptions inform us on the history of the trait under consideration, allows us to see why a specific activity of the trait is an activity this trait is supposed to perform and can offer an account of dysfunction. This is because dysfunction, according to this theory, is simply when a trait cannot perform its selected activity. Moreover, this view is often assumed to be consistent with evolutionary biologists’ thinking about function. Of course, more has been said and can be said regarding such an account, but these advantages lead many to defend and support this view or related views (Godfrey-Smith, 1994; Garson, 2019; Hundertmark and van den Bos, 2024).
However, as always in philosophy, reaching a consensus is challenging, and this “traditional” view has been criticized (Ratti and Germain, 2022; Bellazzi, 2022). In a recent blog post, Dong and Piccinini argue that we should rethink viewing functions as selected effects because novel mutations and novel artifacts are “clearly functional” but have not been selected by any evolutionary process. They propose a new version of the goal contribution account as an alternative.
In our two-part response, we argue that selection is inevitable, as it is necessary to capture functions within organisms and artifacts (in line, for instance, with Garson, 2023). In this first post, we argue for this by showing that the selected effects view can allow function ascriptions in the cases suggested.
2. Do We Need to Rethink Biological Functions?
Is it true that it is impossible to ascribe selected effects functions to novel mutations or artifacts? We don’t think so. First, let’s look at novel mutations. Dong and Piccinini assume these do not have a selection history. This, however, is not generally true. Mutations rarely occur as they do in Teenage Mutant Ninja Turtles. Mutations usually give rise to traits with new capacities in a stepwise process and within an existing lineage. Consequently, these traits inherit their predecessor’s functions. These selected effects functions will be similar but not always equal to the beneficial activities (or goal-contribution functions) the novel mutation can perform. Consider the evolution of the eye. In the first step, simple photoreceptors allowed the detection of light. In the second step, a folded area allowed for directional sensitivity. However, this directional sensitivity was initially only a beneficial side effect.
While opponents of the SE view might use this difference to argue that SE cannot ascribe the correct functions, we see this as an advantage. Suppose we ask what a mutation is supposed to do, that is, its teleological function. The most natural answer would be to cite its SE function (what its predecessors did that accounts for their positive selection) and acknowledge that the mutation produces a slightly different effect, which, by coincidence, contributes better to survival and reproduction. After some time, this effect could, of course, become its new SE function. So, if the fold was successfully selected because it allows detecting the direction of a light source, doing this will become its new function.
Of course, by coincidence, mutations could also bring about entirely new traits with beneficial effects without a stepwise process. However, in such unlikely, X-Men-esque cases, where new abilities suddenly appear out of nowhere, it is implausible that there is something this trait is supposed to do. Consequently, there are also no teleological functions, but only accidentally beneficial effects.
Let’s turn to artifact functions. According to Dong and Piccinini, these have functions without any selection history. This is also no counterexample to the SE theory. First of all, there is prima facie no reason to suppose that artifacts’ functions are the same as functions of biological traits. Of course, it cannot be ruled out that a unified theory of both phenomena is possible. Nevertheless, the distinction between biological and artifact functions is a standard move in the debate, so the force of Dong and Piccinini’s argument is limited (Preston 2022).
That said, the prospects of SE to give such a unified theory are good (Eaton 2020). Some new artifacts have been selected by intentional selection processes. Their users might have (often consciously) selected them for specific purposes, or their parts might have been (consciously) selected by their designers to perform certain functions within artifacts. So, SE theorists can either argue that such selection processes themselves can confer functions to artifacts (Neander 1991, 462) or use Millikan’s (1984, chap. 2) notion of derived proper functions to tie the functions of such artifacts to the selection history of their designer’s intentions.
In sum, Dong and Piccinini do not present sufficient reasons to rethink biological functions since the SE theory can also ascribe functions to novel mutations and artifacts.
Acknowledgments
The authors thank Peter Schulte, James Turner and Maximilian Lipski for their insightful comments on this piece. This article was written thanks to the collaborations promoted by the Functions in Philosophy Network. Get in touch with the authors if you would like to know more.
References
Bellazzi, F. (2022). Biochemical Functions. British Journal for the Philosophy of Science. https://doi.org/10.1086/723241.
Eaton, A. W. (2020). Artifacts and Their Functions. In Ivan Gaskell & Sarah Anne Carter (eds.), The Oxford Handbook of History and Material Culture. Oxford University Press.
Garson, J. (2019). What Biological Functions Are and Why They Matter. Cambridge: Cambridge University Press.
Garson, J. (2023). Putting History Back into Mechanisms. British Journal for the Philosophy of Science 74 (4):921–940.
Godfrey-Smith, P. (1994). A Modern History Theory of Functions. Noûs 28 (3): 344. https://doi.org/10.2307/2216063.
Hundertmark, F. and van den Bos, M. (2024). Biological functions and dysfunctions: a selected dispositions approach. Biology and Philosophy 39 (2):1-20. https://doi.org/10.1007/s10539-024-09944-2
Millikan, R. G. (1984). Language, Thought, and Other Biological Categories: New Foundations for Realism. Cambridge, MA: MIT Press.
Neander, K. (1983). Abnormal Psychobiology. Ph.D. dissertation, La Trobe.
Neander, K. (1991). The Teleological Notion of ‘Function’. Australasian Journal of Philosophy, 69(4): 454–468. https://doi.org/10.1080/00048409112344881
Preston, B. (2022). Artifact, The Stanford Encyclopedia of Philosophy (Winter 2022 Edition), Edward N. Zalta & Uri Nodelman (eds.), URL = <https://plato.stanford.edu/archives/win2022/entries/artifact/>.