The Problem of Religious Diversity
In giving examples of people who believe that the existence of religious diversity constitutes a defeater for religious belief (especially exclusivist religious belief), in Warranted Christian Belief, Plantinga mentions both the 16th century writer Jean Bodin, who thought that each religion is refuted by all of the other religions, and John Hick, who believed that given the knowledge that we have about the other great world faiths, Christian exclusivism is an unacceptable position. We can summarize the objection from religious diversity as follows: Even if one were to grant that religious belief could be warranted without the internal access that grounds the warrant for that belief, it would appear that one would not be rational in holding to any particular metaphysical doctrine in virtue of the vast amount of other religious claims and beliefs available. This type of argument utilizes the equal weight theory, which holds that one should give equal weight to an epistemic peer’s belief or opinion in the case of epistemic disagreement. The argument can best be illustrated in the following syllogism:
(1) It is unreasonable to hold to one’s views in the face of disagreement since one would need positive reason to privilege one’s views over one’s opponent
(2) No such reason is available since the disagreeing parties are epistemic peers and have access to the same evidence
(3) Therefore, one should give equal weight to the opinion of an epistemic peer and to one’s own opinion in the case of epistemic disagreement. (Kim 2011, 49-50)
Is there a good reason for holding to such a view? The Plantigian, Joseph Kim, has argued that the equal weight theory shouldn’t be seen as a threat to Christian belief for at least three reasons. (Kim 2011, 46-65) First, one could accept the equal weight theory but deny that followers of other religions are epistemic peers. If the Spirit of God actually repaired one’s cognitive faculty and testified to the subject, it wouldn’t appear that the subject would be in the same epistemic situation as a subject who perceives that God has revealed Himself (and a different religion) to them, but in reality the belief was a product of wish fulfillment or some cognitive malfunction. This would be true, even if an onlooker couldn’t tell the difference between the two.
Secondly, it would further appear that if the equal weight theory was true, one could not have knowledge about the right conclusions to philosophical paradoxes and even ‘common sense’ philosophical beliefs (this would even include philosophical beliefs about having knowledge of other minds). (Kim 2011, 54-55)This thought can also be applied to science. Take the example of quantum mechanics: if one top scientist takes a non-realist view while another, who is his epistemic peer, takes a realist view, it would follow that according to the equal weight theory, both of them would need to withhold belief about their interpretation.
Lastly, Kim sees good reason to reject the equal weight theory as it would appear that this argument could be self-defeating. For if philosophers in one category, say category A, affirmed the equal weight theory, while another category of philosophers, say category B, denied the equal weight theory, it would follow that philosophers in both categories would not be warranted in believing in the equal weight theory if they were epistemic peers lacking any convincing reasons to privilege one belief over another. Kim believes that the reasons given here give us enough reason to reject the equal-weight theory and this version of the problem of religious diversity altogether.