Abstract
Alvin Plantinga has famously argued that metaphysical naturalism is self-defeating, and cannot be rationally accepted. I distinguish between two different ways of understanding this argument, which I call the "probabilistic inference conception", and the "process characteristic conception". I argue that the former is what critics of the argument usually presuppose, whereas most critical responses fail when one assumes the latter conception. To illustrate this, I examine three standard objections to Plantinga's evolutionary argument against naturalism: the Perspiration Objection, the Tu Quoque Objection, and the "Why Can't the Naturalist Just Add a Little Something?" Objection. I show that Plantinga's own responses to these objections fail, and propose counterexamples to his first two principles of defeat. I then go on to construct more adequate responses to these objections, using the distinctions I develop in the first part of the paper.
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Notes
Alvin Plantinga, “Is Naturalism Irrational?”, Chapter 12 in Warrant and Proper Function (New York and Oxford: Oxford University Press 1993), pp. 216–237. In this book, the evolutionary argument against naturalism is referred to as the “main argument”, and should be distinguished from the “preliminary argument” developed in the same chapter. Also see Alvin Plantinga, “Introduction”, in Naturalism Defeated? Essays on Alvin Plantinga’s Evolutionary Argument Against Naturalism, James Beilby, ed. (Ithaca and London: Cornell University Press 2002a).
A book containing important essays on the argument is Naturalism Defeated? Essays on Alvin Plantinga’s Evolutionary Argument Against Naturalism, James Beilby, ed. (Ithaca and London: Cornell University Press 2002).
The qualification “over some range” is necessary, because it is easy to see that there are many circumstances in which our cognitive faculties are not reliable at all: there are, for example, all those circumstances in which they are not functioning properly (whether due to drugs, illness, or injury), and there are all those circumstances for which the design plan of our cognitive faculties is not appropriate (trying to judge the relative distances of heavenly bodies on the basis of perception would be an example of such a circumstance). In the latter range of circumstances, many would include attempts to solve philosophical problems as well e.g. Colin McGinn, Problems in Philosophy. (Oxford, UK and Cambridge, USA: Blackwell Publishers, 1994).
A reviewer has pointed out to me that, since one can divide up human cognition into different domains, our evaluation of the likelihood of human cognitive faculties being reliable may vary depending on the domain we are considering. This is correct; however, if Plantinga’s argument for the Probability Thesis is sound, then P(R/N&E) will be low or inscrutable no matter what domain we are considering. The reason is that the considerations on which Plantinga’s argument for the Probability Thesis rests are entirely independent of the domain being considered. For more details on Plantinga’s argument for the Probability Thesis, see Alvin Plantinga, “Introduction”, in Naturalism Defeated? ed. Beilby, pp. 5–10.
Plantinga also argues that theism does not suffer from the same problems that he identifies with naturalism (or at least does not suffer from the same problems in the same way). His argument is thus a way of exhibiting a certain advantage he believes theism has over naturalism.
This is the most prominent analogy in the discussions presented in Naturalism Defeated? Essays on Alvin Plantinga’s Evolutionary Argument Against Naturalism, James Beilby, ed. (Ithaca and London: Cornell University Press 2002a). Other analogies, like the Case of the Cartesian Demon, will not be discussed here for lack of space.
Outside of the literature on EAAN, there is significant discussion of whether or not evolution favors true beliefs, and this has a bearing on the Probability Thesis. For example, see C.L. Stephens, “When is it Selectively Advantageous to Have True Beliefs? Sandwiching the Better Safe Than Sorry Argument”, Philosophical Studies 105:2, 2001. However, criticism of EAAN itself tends to focus on the Defeater Thesis.
Alvin Plantinga, “Naturalism Defeated”, (unpublished manuscript: 1994), p. 33.
The distinction between rebutting defeaters and undercutting defeaters was introduced into the literature by John Pollock. His definitions of the terms “rebutting” and “undercutting”, while related to the ones I adopt, are nevertheless quite different. See John Pollock, Contemporary Theories of Knowledge (Lanham, Maryland: Rowman and Littlefield, 1999), pp. 196–197.
Alternative definitions of “rebutting” and “undercutting” can be found in Michael Bergmann, “Defeaters and Higher-Level Requirements”, The Philosophical Quarterly 55:220, 2005, p. 424.
Note that this inference is not meant to be a representation of EAAN itself. This should be clear given that the Defeater Thesis is a premise in EAAN, but appears nowhere among the premises of this inference.
The significance of this inference is merely this. Assuming that the Defeater Thesis is true and that the defeater for R to which it refers is rebutting, then it is in virtue of the support provided by the premises of this inference to its conclusion that the naturalist acquires this rebutting defeater for R.
Alvin Plantinga, “Naturalism Defeated”, (unpublished manuscript: 1994), p. 14. I obtained a copy of this paper from the author. It is also available (although without numbered pages) at http://www.homestead.com/philofreligion/files/alspaper.htm.
Ibid., p. 14. Plantinga does not mention any published sources for these objections.
Branden Fitelson and Elliott Sober, “Plantinga’s Probability Arguments Against Evolutionary Naturalism”, Pacific Philosophical Quarterly 79:2, 1998, p. 124.
The Perspiration Objection itself is such an analogous case, as is the example from Fitelson and Sober mentioned above.
This reply appears in Plantinga, “Naturalism Defeated”, p. 37.
In Naturalism Defeated?, ed. James Beilby, p. 238.
Ibid., p. 239.
Plantinga, “Naturalism Defeated”, p. 41.
Ibid., p. 40.
Ibid., p. 45.
According to Plantinga’s religious epistemology, the source of Christian belief is the Internal Testimony of the Holy Spirit, which gives the believer warrant for the entire complex of traditional Christian belief, (here labeled theism simpliciter), including such things as belief in the Holy Trinity, the reliability of the New Testament, and so on. Belief in the existence of God is a part of this complex, and so gets its warrant from theism simpliciter. This religious epistemology is defended and developed in detail in Alvin Plantinga, Warranted Christian Belief, (New York and Oxford: Oxford University Press, 2000).
Michael Bergmann, “Commonsense Naturalism”, in Naturalism Defeated? ed. Beilby, 2002, p. 63.
Ibid., p. 67.
Ibid., p. 68.
Ibid., p. 73. In fact, Bergmann considers a number of other cases as well, but for the sake of simplicity, we will overlook these here.
Ibid., p. 71.
Ibid., p. 73.
Ibid., p. 73.
Ibid., p. 73.
Ibid., p. 75.
Ibid., p. 74.
Ibid., p. 75.
Ibid., p. 72–73.
Ibid., p. 73. There are many other interesting details and arguments in Bergmann’s paper that we will have to pass over in the interests of space.
Alvin Plantinga, in “Reply to Beilby’s Cohorts” in Naturalism Defeated? ed. Beilby, 2002b p. 230.
Ibid., p. 231.
Ibid., p. 231.
Ibid., p. 232.
The reason is that if the naturalist has no alethic rationality defeater for R in virtue of accepting the Probability Thesis, his belief in R will continue to be alethically rational, which means that the cognitive processes involved in sustaining belief in R are truth-aimed.
One issue which could not be discussed here, due to space limitations, is The Conditionalization Problem. This is the problem of determining which of the naturalist’s beliefs X are such that, if P(R/N&E&X) is high, then the naturalist does not have a defeater for R in virtue of accepting that P(R/N&E) is low or inscrutable. (One possibility for X is that it could be some piece of evidence from contemporary non-evolutionary psychology which supports R.) I am convinced that the ideas developed in this paper can be used to solve the Conditionalization Problem, and I intend to set out this solution in detail in a future article. For a detailed discussion of the Conditionalization Problem, see Alvin Plantinga, “Reply to Beilby’s Cohorts” in Naturalism Defeated? ed. Beilby, pp. 220–225.
Thanks to John MacFarlane, Alvin Plantinga, and an anonymous reviewer for discussion and helpful comments on this topic.
References
Beilby, J. (Ed.). (2002). Naturalism defeated? Essays on Plantinga’s evolutionary argument against naturalism. Ithaca: Cornell University Press.
Bergmann, M. (2002). Commonsense naturalism. In J. Beilby (Ed.). Naturalism defeated? Essays on Plantinga’s evolutionary argument against naturalism (pp. 61–90). Ithaca: Cornell University Press.
Bergmann, M. (2005). Defeaters and higher-level requirements. The Philosophical Quarterly, 55, 220.
Fitelson, B., & Sober, E. (1998). Plantinga’s probability arguments against evolutionary naturalism. Pacific Philosophical Quarterly, 79, 2.
McGinn, C. (1994). Problems in philosophy. Oxford: Blackwell Publishers.
Plantinga, A. (1993). Warrant and proper function. New York: Oxford University Press.
Plantinga, A. (1994). Naturalism defeated. Unpublished manuscript.
Plantinga, A. (2000). Warranted Christian belief. New York: Oxford University Press.
Plantinga, A. (2002a). Introduction. In J. Beilby (Ed.), Naturalism defeated? Essays on Plantinga’s evolutionary argument against naturalism (pp. 204–275). Ithaca: Cornell University Press.
Plantinga, A. (2002b). Replies to Beilby’s cohorts. In J. Beilby (Ed.), Naturalism defeated? Essays on Plantinga’s evolutionary argument against naturalism (pp. 204–275). Ithaca: Cornell University Press.
Pollock, J. (1999). Contemporary theories of knowledge. Lanham: Rowman and Littlefield.
Stephens, C. L. (2001). When is it selectively advantageous to have true beliefs? sandwiching the better safe than sorry argument. Philosophical Studies, 105, 2.
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Mirza, O. A user’s guide to the evolutionary argument against naturalism. Philos Stud 141, 125–146 (2008). https://doi.org/10.1007/s11098-007-9155-3
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DOI: https://doi.org/10.1007/s11098-007-9155-3