Life poses a threat to materialism. To understand the phenomena of animate nature, we make use of a teleological form of explanation that is peculiar to biology, of explanations in terms of what I call the ‘vital categories’ – and this holds even for accounts of underlying physico-chemical ‘mechanisms’. The materialist claims that this teleological form of explanation does not capture what is metaphysically fundamental, whereas her preferred physical form of explanation does. In this essay, I do three things. (1) I argue that the ‘vital categories’, such as life form and life-process, do not reduce to the ‘physical categories’ and show that there are no grounds for the materialist's metaphysically limiting claim; (2) I sketch a positive view on how vital and physical explanations can both apply to a given phenomenon, and on how they interrelate; and (3) I show that this view meshes nicely with evolutionary theory, despite being committed to a form of ‘biological essentialism’.
1 Josh Weisberg, Consciousness (Cambridge: Polity Press, 2014), 13.
2 See Mulder, Jesse M., ‘The Essentialist Inference’, Australasian Journal of Philosophy 91 (2013), 755–69, for a more detailed explication of this notion of fundamentality.
3 I owe this reference to Michael Thompson, Life and Action (Cambridge, MA: Harvard University Press, 2008), 4 (note 3). A translation of Schlick's list can be found in Moritz Schlick, Philosophy of Nature (New York: Philosophy Library, 1949), 73–4. Schlick says he got his list from Wilhelm Roux, the founder of ‘developmental mechanics’, who was deeply involved in the vitalist-mechanist debate around 1890. In those years, Roux's experimentally developed mechanistic theory of embryological development was refuted by experiments of Hans Driesch, who took his own results to support vitalism. See Reinhard Mocek, Wilhelm Roux, Hans Driesch: zur Geschichte der Entwicklungsphysiologie der Tiere (Jena: Fischer, 1974). I briefly look into the vitalist–mechanist debates in the next section.
4 ‘Life’, in Wikipedia. See http://en.wikipedia.org/wiki/Life#Definitions. Retrieved December 16, 2015.
5 Michael Thompson, Life and Action (Cambridge, MA: Harvard University Press, 2008), 39.
6 Ibid., 36.
7 Storrs McCall, ‘The Origin of Life and the Definition of Life’, 174. In Tuomas Tahko (ed.), Contemporary Aristotelian Metaphysics (Cambridge: Cambridge University Press, 2012), 174–86. McCall here follows Paul C. Davies, The Fifth Miracle: The Search for the Origin and Meaning of Life (New York: Simon & Schuster, 1999).
8 Thompson, Life and Action, 37.
9 McCall, ‘The Origin of Life and the Definition of Life’, 175.
10 I should remark that both McCall and Davies in fact do not aim at a reductive understanding of life in life-less terms. Davies argues that there is ‘downward causation’ from the information encoded in the DNA to what happens physically, while McCall argues that, in addition, living things are governed by a special kind of analog information embodied in the structure of space-time – ‘[w]herever life exists, spacetime is filled with smaller, more detailed dynamic patterns that govern growth and development’ (‘The Origin of Life and the Definition of Life’, 181).
11 Thompson, Life and Action, 38.
12 ‘Response to stimuli’ should here not be understood in a behavioristic vein, but rather broadly so as to encompass also phenomena of vegetative life – a plant's responding to incoming sunlight by manifesting the process of photosynthesis, say.
13 Thompson, Life and Action, 39.
14 Ibid., 41.
15 Compare Rödl, Sebastian, ‘Infinite Explanation’, Philosophical Topics 36 (2008), 123 : ‘We may think the following a prime example of a response to a stimulus: I clap my hands, and the cat shies away, hiding under the sofa. The following is just as good an example: I throw the cat into the fire, and she burns to ashes.’ The first is a life-process: it is something that plays a certain role in a cat's life. The second is not: it is a purely physical process which the cat undergoes.
16 For a discussion of putative list-occupants in much more detail than I can do in the context of this article, see Thompson, Life and Action, Part I.
17 Barry Stroud makes an argument of roughly this shape against subjectivist theories of color. He writes: ‘Prior acceptance of the exclusively scientific story of the physical world is what encouraged the idea of perceptions of color as nothing more than “sensations”’ (The Quest for Reality (New York: Oxford University Press, 2000), 182). Here, the ‘exclusively scientific story’ corresponds to the restriction to physical forms of explanation that constitutes my target. By opposing such a ‘negative metaphysical verdict’ about color, Stroud is not arguing for the reality of color. This pessimistic outcome, however, is based on his understanding of the metaphysical ‘quest for reality’ (see also his Engagement and Metaphysical Dissatisfaction (New York: Oxford University Press, 2011)), which I think is mistaken. (See Jesse M. Mulder, Conceptual Realism: The Structure of Metaphysical Thought (Utrecht University: PhD Thesis, 2014), Chapter 1.)
18 G.E.M. Anscombe, ‘Causality and Determination’, 1972, in Anscombe, Collected Philosophical Papers, Vol. 2 (Oxford: Wiley-Blackwell, 1981), 143.
19 It would take us too far afield to explore how this point relates to the notorious controversy between compatibilists and libertarians in the free will debate. As in the case of consciousness, we have here another issue for which the metaphysical status of life may well be of crucial importance. (See Helen Steward, A Metaphysics for Freedom (Oxford: Oxford University Press, 2012) for a view that goes some way towards recognizing this point.)
20 Daniel Dennett, Kinds of Minds: Toward an Understanding of Consciousness (New York: Basic Books, 1996), 24.
21 Vitalism was largely abandoned on such grounds after the first few decades of the twentieth century, but it was still a live option in those early decades – see, e.g., Hans Driesch, The History and Theory of Vitalism (London: MacMillan & Co., 1914). However, Normandin and Wolfe's recent collection of articles on the history of vitalism over the past two centuries – Vitalism and the Scientific Image in Post-Enlightenment Life Science, 1800–2010 (Dordrecht: Springer, 2013) – makes clear that Dennett is massively overstating his case. See, in particular, the contributions by Bechtel (‘Addressing the Vitalist's Challenge to Mechanistic Science: Dynamic Mechanistic Explanation’, ch. 14) and Turner (‘Homeostasis and the Forgotten Vitalist Roots of Adaptation’, ch. 11). The former, a dedicated ‘mechanist’, nevertheless urges that the vitalists were right in recognizing ‘that the mechanist accounts [of their days] lacked the resources to account for some of the most fundamental features of living organisms’ (346), and tries to amend his mechanistic views accordingly; the latter, a dedicated ‘anti-mechanist’, urges that ‘[d]efining a new metaphysics of biology will mean engaging with and incorporating long-shunned “vitalist” concepts’ (287).
22 It is impossible to do justice to the historical and philosophical subtleties of this shift in philosophical thought in the context of a systematically motivated essay. Robert Pasnau provides a thoughtful and very detailed analysis of the relevant metaphysical developments in his Metaphysical Themes 1274–1671 (Oxford: Oxford University Press, 2011).
23 See Mulder, ‘The Essentialist Inference’.
24 Fiona Ellis calls the confusion over the role concepts play in the understanding of reality, which made it seem as if hylomorphism was really rejected, ‘the syndrome’ (Concepts and Reality in the History of Philosophy (London: Routledge, 2005), 1). The skeptical extreme to which this syndrome may lead really does reject hylomorphism because it rejects the very idea that our concepts can capture fundamental aspects of reality at all. See Mulder, Jesse M., ‘What Generates the Realism/Anti-Realism Dichotomy?’, Philosophica 84 (2012), 49–80 .
25 I do not intend to be faithfully representing Aristotle's doctrine of causes; my interests are systematic, not exegetical, and my use of Aristotelian labels is thus meant as expressing allegiance to a broader philosophical orientation, not to a specific metaphysical doctrine.
26 C.D. Broad, The Mind and Its Place in Nature (London: Routledge & Kegan Paul, 1925), 61.
27 Powell, Alexander and Dupré, John, ‘From Molecules to Systems: The Importance of Looking Both Ways’, Studies in History and Philosophy of Biological and Biomedical Sciences 40 (2009), 59 .
28 Notice, though, that physical and biological prediction differ fundamentally. Biological prediction is susceptible to a special kind of failure, arising out of the peculiarity that living things may fail to achieve what they aim at. Given that horses are four-legged, for instance, one is perfectly safe to predict that this pregnant mare will give birth to a foal with four legs. If the foal turns out to have only three, there is a sense in which the prediction is not thwarted, for it is clear that something has gone wrong – the foal should have had four legs, for that is what suits horses. Nothing can go ‘wrong’ in this sense in inanimate nature.
29 John Dupré, ‘It Is Not Possible to Reduce Biological Explanations to Explanations in Chemistry and/or Physics’, in Francisco Ayala and Robert Arp, Contemporary Debates in Philosophy of Biology (Malden, MA: Blackwell Publishing, 2010), 42–3.
30 Dupré at times seems to come close to the kind of view I am proposing, yet he never really distinguishes between physical and vital forms of explanation. The result is that he can only express his anti-reductionism in mereological terms – that is, in terms of ‘the whole’ influencing ‘the parts’. He frequently alludes to the importance of ‘the wider context’ for understanding biological phenomena, in particular on the molecular level, and is positively impressed by ‘systems biology’. See the essays in his Processes of Life: Essays in the Philosophy of Biology (Oxford: Oxford University Press, 2012), and his ‘Living Causes’, Aristotelian Society Supplementary Volume 87 (2013), 19–37 .
31 I ignore the fact that candles are artifacts, and thus involve the purposes of human beings. If you don't like the example, you could substitute Mount Wingen for it – the famous ‘Burning Mountain’ in New South Wales, Australia, where an underground coal seam fire has been going on for thousands of years.
32 Dupré, ‘It Is Not Possible to Reduce Biological Explanations to Explanations in Chemistry and/or Physics’, 42.
33 See David Whitford, Proteins: Structure and Function (Chichester: Wiley, 2005), esp. chs 8 and 11. A good discussion of this example from a philosophical perspective can be found in §4.3 of Andreas Hüttemann, ‘Comparing Part-Whole Reductive Explanations in Biology and Physics’, in Dennis Dieks et al. (eds), Explanation, Prediction, and Confirmation (Dordrecht: Springer, 2011), 183–202. Relevant references to empirical studies of the process can be found there as well.
34 Recall that I am ignoring the fact that candles are artifacts.
35 A notorious case in point is the production of the relevant mRNA-strand, which codes for the protein that is to be produced. Since genes are often distributed over various parts of the total DNA, the transcribed RNA has to be ‘spliced’ at the proper places to remove the non-coding parts (‘introns’), an activity carried out by what is called the spliceosome (Igor Rogozin et al. , ‘Origin and Evolution of Spliceosomal Introns’, Biology Direct 7 (2012), 1–28 , contains interesting observations on this peculiar entity). Another notorious case in point is the production of organelles. For instance, it is unclear for several kinds of organelles whether these can be produced from scratch in a cell, or rather require existing organelles to be copied from. See, e.g., George Mullins, The Biogenesis of Cellular Organelles, (Georgetown, Texas and New York: Landes Bioscience and Kluwer Academic, 2005).
36 Anscombe, ‘Causality and Determination’, 146.
37 Compare, e.g., computers: it is highly unlikely, speaking purely physico-chemically, that our world's stuff should be arranged as it is in our computers so frequently. From a purely physical point of view, nothing further can be said about it – the coming about of these computers in no way offended the laws of nature, of course. But we can understand why they are there if we understand them as artifacts made by humans for specific reasons – that is, if we stop insisting on using only physical explanation and allow for other types of explanation as well.
38 Dobzhansky, Theodosius, ‘Nothing in Biology Makes Sense Except in the Light of Evolution’, American Biology Teacher 35 (1973), 125–9. In that article, Dobzhansky's aim was to stress the status and importance of evolutionary theory in contemporary biology in the face of strong anti-evolutionist campaigns of religious origin. That particular controversy is irrelevant to my concerns.
39 Richard Dawkins, The Blind Watchmaker (New York: Norton, 1996).
40 Various attempts to ground the vital categories in such contingent stability can be found in the literature. They all face Thompson's ‘sub-metaphysical Scylla’. I have made this point with regard to Ruth Millikan's detailed reductive account of ‘proper function’ and related notions, developed in her Language, Thought, and Other Biological Categories (Cambridge, MA: The MIT Press, 1984), in my Conceptual Realism, Chapter 7.
41 Stephen J. Gould, The Structure of Evolutionary Theory (Cambridge, MA: Belknap Press, 2002), 1179.
42 ‘As it applies to organisms’ should not be understood to include a specific stance on the debate over what the ‘unit of selection’ is – individual organisms, species, genes, or something else.
43 Evelyn Fox Keller, ‘It Is Possible to Reduce Biological Explanations to Explanations in Chemistry and/or Physics’, in Francisco Ayala and Robert Arp, Contemporary Debates in Philosophy of Biology (Malden, MA: Blackwell Publishing, 2010), 23.
44 Interestingly, Keller and Dupré, the writers of these two chapters, which are supposed to defend opposing answers to the given question, both notice that their views do not seem to be all that distinct. Both find it important to stress that they are ‘materialists’ (see, resp., Keller, ‘It is Possible…’, 19, and Dupré, ‘It is Not Possible…’, 33). Keller has it relatively easy, for she can unproblematically state that ‘[a]s a materialist, I am committed to the position that all biological phenomena, including evolution, require nothing more than the workings of physics and chemistry’ (21). Dupré, however, has a harder time stating his position. In my interpretation, he does not cleanly separate the thesis that everything is composed of matter (the non-reductive sort of ‘materialism’ he accepts) from materialism in the reductive sense, which precludes him from arriving at a satisfactory form of anti-reductionism. See also §2.1 above, esp. note 30.
45 Charles Darwin, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (London: John Murray, 1859).
46 The label seems to come from Levit, Georgy and Meister, Kay, ‘The History of Essentialism vs. Ernst Mayr's “Essentialism Story”: A Case Study of German Idealistic Morphology’, Theory in Biosciences 124 (2006), 281–307 . In support of his thesis on the ‘essentialism story’, Wilkins cites, amongst others, McOuat, Gordon, ‘From Cutting Nature at its Joints to Measuring It: New Kinds and New Kinds of People in Biology’, Studies in History and Philosophy of Science Part A 32 (2001), 613–45; David Charles, Aristotle on Meaning and Essence (New York: Oxford University Press, 2002); and Winsor, Mary, ‘The Creation of the Essentialism Story: An Exercise in Metahistory’, History and Philosophy of the Life Sciences 28 (2006), 149–74.
47 Wilkins, John, ‘What is a Species? Essences and Generation’, Theory in Biosciences 129 (2010), 141 .
48 The modern synthesis, marked by a milestone publication by Julian Huxley entitled Evolution: The Modern Synthesis (London: Allen and Unwin, 1942), involved many of the great evolutionary biologists and geneticists of the time, including Theodosius Dobzhansky, Ronald Fisher, Sewall Wright, J.B.S. Haldane, Bernhard Rensch, and Ernst Mayr. See Gould, The Structure of Evolutionary Theory, Part I, esp. ch. 7.
49 Wilkins, ‘What is a Species?’, 144.
50 For the relevant background, see John Wilkins, Species: A History of the Idea (Berkeley: University of California Press, 2009), chs. 5 –7. And for a recent defense of something like genetic essentialism see Devitt, Michael, ‘Resurrecting Biological Essentialism’, Philosophy of Science 75 (2008), 344–82.
51 One way of escaping this conclusion is by endorsing ‘saltational evolution’. Darwin, who supported the thesis natura non facit saltus (see On the Origin of Species, 194), was a ‘gradualist’, thinking that evolution proceeds by accumulation of many small steps (see Gould, The Structure of Evolutionary Theory, 146–55). But there were (and are) those who believed that some kind of jump-like macro-evolution was necessary to account for the larger differences observed in nature. See, e.g., William Bateson, Materials for the Study of Variation (London: MacMillan & Co. 1894), and in particular Richard Goldschmidt, The Material Basis of Evolution (New Haven CT: Yale University Press, 1940), who famously named the envisaged results of such larger jumps of nature ‘hopeful monsters’ (see Gould, The Structure of Evolutionary Theory, 390–3). Though ridiculed by the neo-Darwinians, who were establishing the ‘modern synthesis’ in those years, Goldschmidts ideas have been partly vindicated by later scientists; cases of saltational evolution and even his ‘hopeful monsters’ have been identified and studied. See, e.g., Theissen, Günther, ‘The Proper Place of Hopeful Monsters in Evolutionary Biology’, Theory in Biosciences 124 (2005), 349–69 and Page, Robert et al. , ‘Microarray Analysis of a Salamander Hopeful Monster Reveals Transcriptional Signatures of Paedomorphic Brain Development’, BMC Evolutionary Biology 10 (2010), 199 .
52 E.g., Ernst Mayr proposed – and refined over the years – his ‘biological species concept’. An early formulation: ‘Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups’ (‘Speciation Phenomena in Birds’, American Naturalist 74 (1940), 120 ). A later formulation: ‘A species is a protected gene pool. It is a Mendelian population that has its own devices (called isolating mechanisms) to protect it from harmful gene flow from other gene pools’ (Populations, Species, and Evolution (Cambridge, MA: Belknap Press, 1970), 13). As Wilkins notes, however, it seems that Mayr is more concerned with the epistemic than with the ontological aspects of being a species (Wilkins, Species: A History of the Idea, 189).
53 Wilkins, ‘What is a Species?’, 144.
54 See Wilkins, ‘What is a Species?’, 142. He also refers to Wittgenstein's notion of ‘family resemblance’ (145), remarking that family members resemble each other, of course, because of shared generative histories.
55 John Wilkins, ‘A List of 26 Species “Concepts”’, Science Blogs: Evolving Thoughts, retrieved December 16, 2015: http://scienceblogs.com/evolvingthoughts/2006/10/01/a-list-of-26-species-concepts/
56 In fact, empirical support for this way of thinking can be found in the varieties of epigenetic inheritance – inheritance of acquired traits – that are currently being researched. Eva Jablonka, Marion Lamb, and Gal Raz present interesting findings, and argue that ‘[i]ncorporating epigenetic inheritance into evolutionary theory extends the scope of evolutionary thinking and leads to notions of heredity and evolution that incorporate development’ ( Jablonka and Raz, ‘Transgenerational Epigenetic Inheritance: Prevalence, Mechanisms, and Implications for the Study of Heredity and Evolution’ Quarterly Review of Biology 84 (2009), 167 ). They view themselves as ‘challenging the modern synthesis’, with its narrow focus on genes as the sole locus of evolution, and reintroduce ideas from the history of evolutionary theory that were banned from the modern synthesis because they do not fit the reductive project – e.g., Lamarckian ideas and saltational evolution (see note 50 above). See Jablonka and Lamb, Evolution in Four Dimensions (Cambridge, MA: The MIT Press 2005); Jablonka and Lamb, ‘Bridging the Gap: The Developmental Aspects of Evolution’, Behavioral and Brain Sciences 30 (2007), 378–89; and Jablonka and Lamb, ‘Soft Inheritance: Challenging the Modern Synthesis’, Genetics and Molecular Biology 31 (2008), 398–95.
57 For this essay, I have benefited greatly from conversations on its central ideas with the following people: Niels van Miltenburg, Thomas Müller, Dawa Ometto, Michael Thompson, Antje Rumberg, and Joeri Witteveen. I also gratefully acknowledge financial support from the European Research Council, under the European Community’s Seventh Framework Programme (FP7/2007–2013), ERC Grant agreement numbers 263227 and 616512.
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