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Natural Selection Explanation and Origin Essentialism1

Published online by Cambridge University Press:  01 January 2020

Joel Pust
Joel Pust*
Affiliation:
University of Delaware, Newark, DE19716-2567, USA
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Does natural selection explain why individual organisms have the traits that they do? This question has been the subject of vigorous debate in recent philosophy of biology. Sober and Walsh have defended the thesis that natural selection does not explain why any individual organism has the traits that it does. This thesis, I shall call ‘the Negative View.’ Neander and Matthen have defended the contrary thesis, which I shall call ‘the Positive View,’ according to which natural selection at least sometimes does explain why an individual organism has the traits that it does. In this paper, I will argue that recent arguments for the Positive View fail for a reason hitherto unnoticed and I will demonstrate that other recent defenses of the Negative View depend upon my own for their plausibility.

I begin, in Section II, by showing that the issue is whether or not natural selection explains, of an individual, why it has the traits it does.

Type
Research Article
Information
Canadian Journal of Philosophy , Volume 31 , Issue 2 , June 2001 , pp. 201 - 220
Copyright
Copyright © The Authors 2001

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Footnotes

1

I am grateful to André Ariew, Mohan Matthen, Thomas Bontly, Holly Feldheim, Jeff Jordan, Michael Rea, Michael Bergmann, Karen Neander, Robert Cummins, Robin Andreasen, Elliott Sober, Lisa Downing, and an anonymous referee for helpful comments on previous drafts of this paper. I owe a special debt to Denis Walsh and Christopher Boorse for detailed and helpful comments on multiple previous drafts. Work on this paper was supported by a General University Research Grant from the University of Delaware.

References

2 The primary disputants have been Neander, Karen ‘What Does Natural Selection Explain? Correction to Sober,’ Philosophy of Science 55 (1988) 422-6CrossRefGoogle Scholar, ‘Pruning the Tree of Life,’ British Journal for the Philosophy of Science 46 (1995) 59-80, and ‘Explaining Complex Adaptations: A Reply to Sober's “Reply to Neander”,’ British Journal for the Philosophy of Science 46 (1995) 583-7; Matthen, Mohan ‘Evolution, Wisconsin Style: Selection and the Explanation of Individual Traits,’ British Journal for the Philosophy of Science 50 (1999) 143-50CrossRefGoogle Scholar; Sober, Elliott The Nature of Selection (Cambridge, MA: The MIT Press 1984)Google Scholar and ‘Natural Selection and Distributive Explanation: A Reply to Neander,’ British Journal for the Philosophy of Science 46 (1995) 384-97; and Walsh, Denis ‘The Scope of Selection: Sober and Neander On What Natural Selection Explains,’ Australian Journal of Philosophy 76 (1998) 250-64CrossRefGoogle Scholar.

3 Millikan, Ruth ‘Seismograph Readings for “Explaining Behavior”,’ Philosophy and Phenomenological Research 50 (1990) 807-12, at 810CrossRefGoogle Scholar, appears to endorse something like the Positive View. However, her remarks seem to me not to distinguish between explanations of why a token biological item exists and explanations of why a token biological item occurs in a particular individual organism. Her discussion seems be a defense of the claim that performances of certain functions on the part of past token traits causally contribute to the existence of present tokens of the trait. This claim does not entail that the fact that a particular individual has a trait is explained by the performances of past functions.

4 Dretske, F. Explaining Behavior (Cambridge, MA: The MIT Press 1988)Google Scholar, ‘Reply to Reviewers,’ Philosophy and Phenomenological Research 50 (1990) 819-39

5 Carruthers, P. Human Knowledge and Human Nature (Oxford: Oxford University Press 1992)Google Scholar; Goldman, A. ‘Innate Knowledge,’ in Innate Ideas, Stich, S. ed. (Los Angeles: University of California Press 1975)Google Scholar

6 This point is made by Cummins, R. ‘Functional Analysis,’ Journal of Philosophy 72 (1975) 741-65, at 751CrossRefGoogle Scholar; Sober, The Nature of Selection, 150Google Scholar; and Walsh.

7 Contrary to Walsh, however, we cannot construe the populations in question as sets unless we wish to give up the claim that selection can explain the distribution of traits in a particular population at a particular time. This is because sets have their members essentially. If, for reasons I provide later, we see selection as only able to determine which organisms exist and we treat populations as sets, then any difference in selection will produce a different population and we will be unable to say that selection explains why this very population has this distribution of traits rather than some other.

8 Dretske, F. ‘Contrastive Statements,’ Philosophical Review 82 (1973) 411-37Google Scholar; Garfinkel, A. The Forms of Explanation (New Haven: Yale University Press 1981);Google Scholar Sober, The Nature of Selection; and Woodward, J. ‘A Theory of Singular Causal Explanation,’ Erkenntnis 21 (1984) 231-62CrossRefGoogle Scholar

9 Lewis, D. ‘Causation,’ in Philosophical Papers vol. 2 (New York: Oxford University Press 1986)Google Scholar

10 So far as I can see, nothing here hangs on the counterpart-vs.-strict-identity debate, and my arguments should be equally acceptable on a counterpart-theoretic account of identity across possible worlds.

11 Neander explicitly admits that explanation is contrastive in the way just outlined ('Pruning,’ 69) and she invokes exactly the contrasting alternatives I mentioned. Neander's acceptance of the distinction between (1) and (2), her understanding of the contrasting cases, and her recognition that (1) is the issue are all evident in the following passage in which she characterizes the view with which she disagrees:

Elliott Sober has argued that natural selection cannot explain why you or I have the traits we do. For example, he says it cannot explain why you or I have opposable thumbs, for while it can explain why individuals with that trait exist (as opposed to some other individuals) it cannot explain why we have that trait (as opposed to some other trait). ('Explaining,’ 583)

Neander is clearly claiming here that the main issue between her and her opponents is whether natural selection can answer questions like (D).

12 Forbes, G. The Metaphysics of Modality (Oxford: Oxford University Press 1986)Google Scholar; Kripke, S. Naming and Necessity (Princeton: Princeton University Press 1980)Google Scholar; McGinn, C. ‘On the Necessity of Origin,’ Journal of Philosophy 73 (1976) 127-35CrossRefGoogle Scholar

13 Graeme Forbes offers a more precise statement of the thesis and detailed arguments for it. Robertson, Teresa ‘Possibilities and the Arguments for Origin Essentialism,’ Mind 107 (1998) 729-49CrossRefGoogle Scholar, criticizes Forbes’ and others’ arguments.

14 On the individuation of populations, see note 7.

15 Matthen notes that Neander hints at this argument when she remarks that ‘For [our ancestors] to mate with the mates they did, they mustn't have mated with anyone else instead, including any of the creatures that natural selection eliminated’ ('Pruning,’ 78).

16 If, however, OE is false, then it may be possible to maintain that (F) is true. Of course, how plausible it is to claim that counterfactuals like (F) are true depends upon the alternative criterion of individuation (other than origin) endorsed. Matthen occasionally writes as though being the progeny of a particular organism suffices as a transworld individuation condition. This won't work for biparental organisms, because if an organism's actual parents had both reproduced with other organisms, then both resulting organisms would, on this criterion, be identical to the original organism.

17 I believe the same is true of Walsh, but I shall not attempt to substantiate this claim in this paper.

18 The earlier point about the individuation of populations is relevant here as well. Sober is taking ‘generation III’ to be a non-rigid designator which designates different organisms in different possible worlds.

19 I am indebted to Denis Walsh for insisting that I address this point.

20 Though I think Sober (and Walsh) rely upon OE in arguing against the Positive View, I do not claim that the falsity of OE would suffice to establish the Positive View. See footnote 16.

21 Matthen's article appeared after this paper was largely completed. My identification of OE as the issue between the Positive and Negative Views was independent of Matthen's. Though Matthen notes OE's role in the present debate, he does not mention that OE is a doctrine frequently discussed in contemporary metaphysics.

22 I do not mean to imply that such actions cannot be wrong, nor that such actions cannot involve wronging the resulting persons.

23 Parfit, D. Reasons and Persons (Oxford: Oxford University Press 1984)Google Scholar

24 Some of these misleading intuitions may be produced by a Cartesian notion of the self as some nonphysical substance which could be ‘attached’ to different bodies in different possible worlds (Forbes, 134). Whatever the merits of this view of personal identity, OE is more difficult to resist if one reads it to apply only to organism identity, and this is surely all that is required for evolutionary biology.