What's Wrong With Plantinga's Proper Functionalism? (Draft)

DRAFT
I. Plantinga's Reformed Epistemology and His Mature Account of Warranted Belief
Since the 60s, Alvin Plantinga has been arguing that belief in God is "properly basic". That is, belief in God can rational wholly apart from propositional evidence and argument. This thesis constitutes the core idea of his version of so-called "Reformed Epistemology".

Plantinga's mature defense of his thesis is grounded in a proper functionalist version of epistemic externalism. Plantinga summarizes his account as follows:

"Put in a nutshell, then, a belief has warrant for a person S only if that belief is produced by cognitive faculties functioning properly (subject to no dysfunction) in a cognitive environment that is appropriate for S's kind of cognitive faculties, according to a design plan that is successfully aimed at truth."[1]

So that's what's required for a belief to have any warrant at all. But Plantinga allows that warrant admits of degrees, and he ties the degree of warrant a belief enjoys to the degree of firmness with which it is believed.[2] Thus, for a belief to have a degree of warrant sufficient for knowledge, it must be held with a very high degree of firmness. Putting these points together, Plantinga's account can be summed up as follows:

I. Conditions of warrant are met + high degree of firmness = high degree of warrant.
II. Conditions of warrant are met + low degree of firmness = low degree of warrant.

So that's Plantinga's account of warranted belief in a nutshell. But how does this account connect to his account of warranted theistic belief in particular?

II. Plantinga's Mature Account of Warranted Theistic Belief: The A/C Model[3]
Plantinga argues that it's epistemically possible (consistent with what we know or reasonably believe) that God has designed us in such a way that we are naturally endowed with a cognitive faculty -- what he calls the sensus divinitatis -- that, when functioning properly in epistemically congenial environments reliably and spontaneously produces true beliefs about God. So, for example, when one looks at the starry heavens, the sensus divinitatis is (when functioning properly) naturally disposed to spontaneously trigger the belief, "God made all this"; when doing something wrong, it's disposed to trigger the belief, "God disapproves of what I've done"; etc. And since such belief meets all of the conditions of warrant (viz., (a) it's produced by a properly functioning cognitive faculties (viz., the sensus divinitatis), (b) the faculty is successfully aimed at truth, (c) the environment in which such beliefs are formed is epistemically congenial, Plantinga's account entails that such belief enjoys at least some measure of warrant. And if (d) the belief is held with a very high degree of firmness, the degree of warrant enjoyed by the believer’s belief is sufficient to constitute knowledge (assuming that the belief isn't subject to undefeated defeaters).

We've now looked at Plantinga's account of warranted belief in general and his account of warranted theistic belief in particular. It is now time to take a look at his account of warranted Christian belief.

III. Plantinga's Mature Account of Warranted Christian Belief: The Extended A/C Model[4]
Very roughly, on Plantinga’s model of warranted Christian belief (what he calls the Extended A/C Model, inspired as it is by the writings of Aquinas and Calvin), the Holy Spirit acts on the believer by repairing the sensus divinitatis  from the ravages of sin, so that it naturally, spontaneously, and reliably produces true belief about God in the basic (i.e., non-inferential) way. Furthermore, the Holy Spirit acts directly on the spirit of a person true produce a firm and unwavering belief in the core truths of Christianity (what he calls the Great Things of the Gospel).[5]  And since such belief meets all of the conditions of warrant (viz., (a) it's produced by properly functioning cognitive faculties, (b) the faculties are successfullly aimed at truth, (c) the environment in which they're formed is epistemically congenial; therefore, Plantinga's account entails that such Christian belief enjoys at least some measure of warrant. And if (d) (due to the internal instigation of the Holy Spirit and its repairs to the sensus divinitatis) the belief is held with a very high degree of firmness, the degree of warrant enjoyed by the believer’s belief is sufficient to constitute knowledge (assuming that the belief isn't subject to undefeated defeaters).

We've now seen a sketch of Plantinga's account of warranted belief in general and of warranted Christian belief in particular. What to make of his accounts? I mention seven criticisms below that have real bite (for more elaboration, click on the links).

 IV. Criticisms of Plantinga's Account of Warranted Belief that Have Real Bite
With respect to his account of warranted Christian belief in particular: (i) His analysis of warranted Christian belief can't adequately account for the variability of belief among Christians[6]; (ii) his postulation of a sensus divinitatis in human beings is at odds with the empirical evidence[7]; and (ironically) (iii) his account entails that the belief of most Christians has little by way of warrant[8].  But deeper problems lie with his basic account of warrant (see below).

With respect to his account of warranted belief in general: (i) His case for a theistic version of proper functionalism is undercut[9]; indeed, (ii) his theistic version of proper function entails that no beliefs have warrant[10] (iii) his proper functionalist amendment to straight reliabilism is unmotivated[11] and (iv) his account of warrant is subject to counterexamples[12] with respect to both to the necessity and sufficiency of the conditions he proposes.

For these reasons, Plantinga's proper functionalism fails to show that Christian or theistic belief can be warranted in the basic or non-inferential way, or even how beliefs can be warranted in general.

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[1] Warranted Christian Belief, p. 156.
[2] "We must add, furthermore, that when a belief meets these conditions and does enjoy warrant, the degree of warrant it enjoys depends on the strength of the belief, the firmness with which S holds it." (Ibid.) 
[3] The following is a rough summary of some key points in ch. 6 of Warranted Christian Belief.
[4] The following is a very rough summary of some key points in chs. 7-9 of Warranted Christian Belief.
[5] This part is a bit tricky. For according to the model, the Holy Spirit doesn't produce warranted Christian belief via the cognitive faculty of the sensus divinitatis. Rather, it produces it directly. Therefore, strictly speaking, specifically Christian belief isn't produced by a reliable cognitive faculty, but rather by a reliable process. As you might have guessed, people have raised concerns about this. See, for example, Craig and Moreland's Philosophical Foundations for a Christian Worldview (IVP, 2003), pp. 168-169; Beilby, James. Epistemology as Theology: An Evaluation of Alvin Plantinga's Religious Epistemology (Ashgate, 2005), pp.151-153.
[6] Cf. Beilby, Epistemology as Theology, pp. 153-156.
[7] "Divine Hiddenness and the Demographics of Theism" (Religious Studies 42 (2006), pp. 177-191.
[8] See, for example, Beilby. "Plantinga's Model of Warranted Christian Belief", in Peter-Baker, Deane. Alvin Plantinga (Cambridge University Press, 2007), p. 146; DeRose, Keith."Are Christian Beliefs Properly Basic?" APA Eastern talk, 1998. Available here; Chignell, Andrew. "Epistemology for Saints: Alvin Plantinga's Magnum Opus", Books & Culture (March/April 2002), p. 21.
[9] Cf. Wunder, Tyler. "Anti-Naturalism and Proper Function”, Religious Studies 44 (2008), pp. 209-224; Bardon, Adrian. “Reliabilism, Proper Function, and Serendipitous Malfunction”, Philosophical Investigations 30:1 (Jan. 2007), pp. 47-64; Graham, Peter. "Intelligent Design and Selective History: Two Sources of Purpose and Plan" (in Jonathan Kvanvig, ed. Oxford Studies in Philosophy of Religion, Volume 3, 2011). (A link to the paper can be found here)
[10] In addition to my formulation at the link above, see R. Douglass Geivett and Greg Jesson. "Plantinga's Externalism and the Terminus of Warrant-Based Epistemology", Philosophia Christi 3:2, pp. 329-340.
[11] Feldman, Richard. “Proper Functionalism”, Nous 27 (1993), pp. 34-50.
[12] See, for example, Greco, J. 2003. “Virtue and Luck, Epistemic and Otherwise,” Metaphilosophy 34:3, 353-6; Lehrer, Keith. "Proper Function vs. Systematic Coherence", in Kvanvig, Jonathan. Warrant in Contemporary Epistemology: Essays in Honor of Plantinga's Theory of Knowledge (Rowman & Littlefield, 1996), pp. 25-46, esp. pp. 32-33; Feldman, “Proper Functionalism”,  pp. 34-50; Senor, Thomas. “A Critical Review of Alvin Plantinga’s Warranted Christian Belief”, International Philosophical Quarterly 42:3, Issue 167 (September 2002), 395-396.