¹ Alvin Plantinga Warrant and Proper Function (New York NY: Oxford University Press, 1993).

² See, for example, the essays contained in James Beilby (ed.) Naturalism Defeated? Essays on Plantinga's Evolutionary Argument Against Naturalism (Ithaca NY: Cornell University Press, 2002).

³ To date, the only articles which focus exclusively on this argument are Levin, Michael ‘Plantinga on functions and the theory of evolution’, Australasian Journal of Philosophy, 75 (1997), 83–98CrossRefGoogle Scholar; Markie, Peter ‘Plantinga, metaphysical naturalism and proper function’, Southwest Philosophy Review, 15 (1999), 65–72CrossRefGoogle Scholar. Richard Swinburne, Bruce Hunter, and Graham Oppy have also addressed the argument, although each does so as part of a larger critique. See Swinburne, Richard ‘Response to warrant’, Philosophy and Phenomenological Research, 55 (1995), 415–419CrossRefGoogle Scholar; Hunter, Bruce ‘Knowledge and design’, Philosophy and Phenomenological Research, 59 (1999), 309–334CrossRefGoogle Scholar; Graham Oppy ‘Natural theology’, in Deane-Peter Baker (ed.) Alvin Plantinga (New York NY: Cambridge University Press, 2007), 32–34.

⁴ Larry Wright serves as an example of such a naturalist: ‘Specifically, it seems to me consistent, appropriate, and even common for an atheist to say that the function of the kidney is elimination of metabolic wastes’; WPF, 195, citing Wright, Larry ‘Functions’, Philosophical Review, 82 (1973), 82CrossRefGoogle Scholar.

⁵ In a nutshell, warrant is that property or quality of a belief which is responsible for distinguishing full-blown knowledge from merely true belief. According to proper functionalism, a belief is warranted if (and only if) it is produced by cognitive faculties which are functioning properly in an environment suitable for their operation; as well, said faculties must be both reliable and truth-oriented. If a belief satisfies these conditions then its degree of warrant will correspond to the confidence with which the belief is held.

⁶ Elsewhere he agrees intention is not sufficient for proper function (see WPF, ch. 2; cf. 196, n. 2).

⁷ Granting, of course, that the paradigm cases of proper function really are artifactual. Note that the application of organic terms like ‘health’ to artifacts is much more strained, although still comprehensible, than the application of alleged artifact terms like ‘proper function’ to the organic world. This suggests that it is much more plausible that the paradigm cases of health et al. are exclusively organic than that the paradigm cases of proper function et al. are exclusively artifactual.

⁸ And this problem only gets worse when we find that Plantinga's intuitions tell him garden patches and ecosystems have proper functions (see WPF, 198). Indeed, even if he had not admitted this we could have inferred it: for if divine design entails design plans, and therefore proper functions, then theism implies the entire created world will have a proper function; so will any of its constituents which can be said to possess a design plan. Even if some naturalists will agree with Plantinga that entire organisms have functions and proper functions (e.g. survival and reproduction), I doubt many will intuit that, say, the proper function of rain is to nourish the earth and its living inhabitants.

⁹ There is reason for both naturalists and theists to see their organic uses of proper function this way. Following Richard Swinburne's ‘Response’, I suggest theists and naturalists alike have two sets of concepts regarding artifactual and organic normativity: Swinburne describes them as the ‘naturalistic’ and the ‘supernaturalist’ concepts of proper function; Plantinga thinks ‘naturalistic’ and ‘designer’ are more accurate (see Plantinga, ‘Reliabilism, analyses and defeaters’, Philosophy and Phenomenological Research, 55 (1995), 454–455CrossRefGoogle Scholar), but I think ‘organic’ and ‘artifactual’ are better still. Those things Plantinga considers organic proper functions can be understood with the organic family of terms, without taking on the divine-design analogy and certainly without taking on the origins implied by that analogy. This is, I suspect, because theists and atheists alike really do typically understand the use of ‘proper function’ in the natural world as an analogous extension of our organic notions into mechanical-sounding language. The designer analogy can only clumsily shadow what we learn via our naturalistic (i.e. non-design) understanding of the organic world, tacking to the end of any ascription of organic proper function ‘and it is this way because God made it so’. Given the lack of plausible divine revelations concerning these matters, it seems doubtful that divine intentions really can figure, analogically or otherwise, too extensively into our discoveries of, and theories about, proper function; a fortiori they seem irrelevant to our ascriptions of the term.

¹⁰ I will not assume, however, that the paradigm cases of organic health et al. are artifactual since this is obviously false.

¹¹ More formally, this is the distinction between the design plan and the max plan; the former is a list of those proper functions anticipated/intended by the designer; the latter is a list of how something functions in all logically possible scenarios. It is unclear to me how the distinction arises when the designer in question is omniscient. See WPF, 22–24 for the full explication of the distinction.

¹² See Pollock, John ‘How to build a person: the physical basis for mentality (volume 1: metaphysics)’, NoÛs Supplement: Philosophical Perspectives, 1 (1987), 109–154Google Scholar.

¹³ See Ruth Millikan Language, Thought, and Other Biological Categories: New Foundations for Realism (Cambridge MA: MIT Press, A Bradford Book, 1984).

¹⁴ See Bigelow, John and Pargetter, Bruce ‘Functions’, Journal of Philosophy, 84 (1987), 181–196CrossRefGoogle Scholar.

¹⁵ Quoting Pollock ‘How to build a person’, 148.

¹⁶ One could try to face these counter-examples head on. For example, we might agree that it is not the proper function of sperm to fertilize eggs, but rather to do something that most sperm do, statistically speaking, end up doing (e.g. wriggling through seminal fluid); fertilization would be the proper function of some entity or process that does, with sufficient statistical propensity, lead to fertilization. But I do not wish to pursue this point, here, and will accept, with Plantinga, that some proper functioning is not statistically normal.

¹⁷ It is recognition of this point that seems to drive Plantinga toward his paradigm-cases model of conceptual analysis (see below).

¹⁸ See WPF, 62, 208, for examples of Plantinga's invocations of Russell's case and a deceiving Cartesian demon.

¹⁹ Perhaps the split will fall on the same line as that between those who think God can make anything at all moral, and those who think a morality which is so arbitrary is no morality at all.

²⁰ Louis Pojman What Can We Know? An Introduction to the Theory of Knowledge (Belmont CA: Wadsworth, 1995), 165. Cf. Swinburne: ‘The trouble with this argument of Plantinga [sic] is that the fact that the naturalist cannot give a useful necessary-and-sufficient conditions analysis of “proper function” doesn't mean that it isn't an intelligible and applicable concept – see of course Wittgenstein's discussion of the notion of a “game”, and what Plantinga himself says about “knowledge”. All that is [sic] means is that “proper function” in the naturalistic sense, like “game”, is a term whose criteria of correct use are established so predominantly by standard examples of correct application and so little by its logical relations to other terms that for kinds of examples remote from clear standard examples, it is unclear what counts as “proper functioning”’; Swinburne ‘Response to warrant’, 417.

²¹ Plantinga ‘Reliabilism, analyses and defeaters’, 454, n. 26.

²² Ruth Millikan suggests there is a distinction between conceptual analysis, finding necessary and sufficient conditions for applying terms which cohere with our intuitions, and theoretical definitions which are acceptable insofar as they are part of a successful scientific theory of the phenomenon in question. She has a rather low regard for conceptual analysis: ‘Now I firmly believe that “conceptual analysis,” taken as a search for necessary and sufficient conditions for the applications of terms, or as a search for criteria for application by reference to which a term has the meaning it has, is a confused program, a philosophical chimera, a squaring of the circle, the misconceived child of a mistaken view of the nature of language and thought’; Ruth Millikan ‘In defense of proper functions’, reprinted in Colin Allen, Marc Beckoff, and George Lauder (eds) Nature's Purposes: Analyses of Function and Design in Biology (Cambridge MA: MIT Press, A Bradford Book, 1998), 297.

²³ I would like to thank Michael Martin for providing comments upon earlier drafts of this article, both before and after it was a chapter in my dissertation. I would also like to thank Sylvia Bryce-Wunder for greatly improving the penultimate draft by not letting me use ‘broadly logically possibly false’ in more than one sentence.