Monday, October 11, 2010

The End of Skeptical Theism? (Part 9) - Warranted Beliefs and Epistemic Defeaters

This post is part of my series The End of Skeptical Theism? For an index, see here.

Previous entries in this series have afforded us the opportunity to consider the unwelcome implications of the skeptical theist response to Rowe's evidential problem of evil. In particular, we have seen how the skeptical theist's appeals to cognitive limitation and unrepresentative sampling may force a regular theist to give up their epistemic rights to a whole series of beliefs that are essential to their theism.

These unwelcome implications are, I believe, enough to put to rest the entire ST-enterprise. Nevertheless, there is a further problem with ST that I want to explore in the final stage of this series. The problem has a somewhat more specialist flavour as it focuses specifically on the difficulties that ST poses for Alvin Plantinga's religious epistemology.

My primary source for this material is the following article:
I have come across similar thoughts in some of Evan Fales's writings. But since Fales leaves those thoughts relatively undeveloped, Naquin's article is the place to go.

Naquin's argument is essentially that ST provides an undercutting defeater for Alvin Plantinga's model of warranted Christian belief. To understand this argument, we first need to understand the nature of Plantinga's religious epistemology. Then we need to understand the nature of an epistemic defeater. Finally, we need to consider Plantinga's alleged defeater to the naturalistic worldview.

1. Warranted Christian Belief: The Extended A/C Model
I already have two posts on which provide, in my opinion, a reasonable summary of Alvin Plantinga's religious epistemology. The first part covers the motivations behind Plantinga's work, and the second part covers Plantinga's specific models of warranted belief. I would encourage you to read those and come back. There is also, for the undaunted, this epic interview with Tyler Wunder covering the same material in much more depth.

For present purposes, I will attempt a more bite-sized summary of Plantinga's work. Put simply, Plantinga's goal is to show how it is possible to have religious knowledge without the assistance of evidence.

"Knowledge", for Plantinga, is taken to denote warranted true belief. But classically, knowledge was said to be justified true belief, where justification was understood to arise from some subjective (internal) deduction or induction from available evidence and/or foundational beliefs. The legacy of 20th century epistemology has been to dismiss as insufficient (for knowledge) the process of internal justification; warrant is simply whatever replaces justification in a completed theory of knowledge.

Plantinga's account of warrant is based on the notion of proper function. He says that one has warranted beliefs whenever the following four conditions are met:
  1. The beliefs are produced by a properly functioning cognitive faculty.
  2. The cognitive environment in which the belief is formed is sufficiently similar to the one for which the cognitive faculties were designed.
  3. The cognitive faculties were the product of a design plan that was aimed at truth.
  4. The design plan was one with a high objective probability of producing truth-apt cognitive faculties.

The thing to note about these conditions is that they are all external to the agent. This allows Plantinga to say that one can have knowledge of something without knowing exactly why or how one has that knowledge. To put it another way: one can have knowledge without evidence. To be sure, there is an internal component to Plantinga's account that focuses on the coherence of one's noetic structure, but it is relatively less important.

With the proper function account tucked under his arm, Plantinga proceeds to develop a model of Christian belief that meets the four conditions of warrant. He argues that if God created the world, we can expect him to have created us with reliable, truth-apt cognitive faculties. We can also expect him to create cognitive faculties (e.g the sensus divinitatus) that would produce religious beliefs, including the belief in God and in the major doctrines of Christianity, in appropriate environments.

This gives rise to the Extended Aquinas/Calvin Model of warranted Christian belief. This is illustrated in the diagram below. It grants the Christian the possibility that their beliefs are true even if they have no evidence for their truth.

2. Defeaters
Although Plantinga is adamant that a Christian can have warranted properly basic beliefs about the major doctrines of their religion, he does not go so far as to say that these beliefs are unchallengeable. He accepts that one could be presented with defeaters that would, rightly, undercut one's confidence in certain beliefs.

Three types of defeater are identified by Plantinga:
  • A Proper Function Defeater: This arises when someone must doubt or deny the truth of a proposition in order to maintain normal functioning. An example might be a person with a debilitating illness who must believe their chances of survival are higher than they actually are in order to live a normal life.
  • The Purely-Alethic Defeater: This works from the third-person perspective. It gives an objective observer a reason to doubt the reliability of some cognitive faculty. For example, suppose your friend Crystal is convinced that she is being persecuted by the CIA. You know that Crystal has been diagnosed as a paranoid schizophrenic and is prone to such delusions. Thus, you have reason to doubt her beliefs. Note, however, that she does not (yet) have reason to doubt her own beliefs.
  • The Humean Defeater: This is a purely alethic defeater that reflexively applies to your own belief-forming faculties. For example, suppose you currently believe that the furniture around you is singing and dancing. Ordinarily, these kinds of perceptions might count as warranted. However, a few moments before this you took some LSD, which you know to be a powerful hallucinogenic. Thus, you have reason to doubt that your current perceptual beliefs are true.

Plantinga goes on to note that all three of these defeaters could arise in a single case. The case is a purely hypothetical one involving a drug called XX. The drug damages one's cognitive faculties and induces hallucinations. Your friend takes the drug but cannot function properly if he believes his faculties are impaired. He tells you that his doctor told him he was immune to the effects. But you realise that this encounter with the doctor is likely to be a hallucination. Thereby, you acquire a purely alethic defeater for that proposition. You share this with your friend and he acquires a Humean defeater for his belief.

The importance of all this is that if one wishes to challenge Plantinga's A/C model, one must supply some sort of defeater to the believer. This defeater must cause them to doubt that their beliefs satisfy the four conditions of warrant. This is exactly what Naquin tries to do.

3. Naturalism Defeated
Plantinga uses his approach to warrant and defeat to develop a defeater to the naturalistic worldview. Plantinga argues that the naturalist must think that their cognitive faculties were designed by the process of evolution. 

In order for the beliefs formed by these cognitive faculties to be warranted, the evolutionary design process must be one with a high objective probability of producing truth-oriented cognitive faculties. The problem, as Plantinga sees it, is that the probability that evolution would give rise to such faculties is either low or inscrutable. This is because evolution aims a survival value not truth.

There are reasons to doubt Plantinga's argument (to defeat his defeater). For example, it may be that there is considerable overlap or coincidence between what is good for survival and what is true. This coincidence would raise the probability that we have reliable cognitive faculties. For present purposes, these counter-arguments are irrelevant. We can grant Plantinga the success of his argument.

What we need to focus on is the distinction Plantinga makes between theism and naturalism. On the one hand, he thinks he has provided a defeater for all aspects of naturalistic cognition by showing how there is no reason to think evolved cognitive faculties satisfy the four conditions of warrant. On the other hand, he thinks he can vindicate Christian theism because there is every reason to think that the Christian God created us with cognitive faculties that satisfy the four conditions of warrant.

This is where Naquin thinks Plantinga goes wrong. He thinks that by using the basic precepts of ST, it is possible to construct a defeater for Christian theism that directly mirrors the defeater that Plantinga constructed for naturalism. We'll begin looking at that argument in the next part.

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