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Plantinga’s Naturalism Defeater

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Way back in the distant past of 2010 Justin Brierly over at his show ‘Unbelievable?‘ moderated a discussion between philosophers Stephen Law and Alvin Plantinga. The topic of debate was Plantinga’s infamous argument that the conjunction of naturalism and evolution renders cognitive reliability improbable. The conjunction is therefore supposedly a defeater against believing in the truth of beliefs produced by our cognition; including the belief in naturalism and evolution. Naturalism, says Plantinga, thereby undermines itself.

Image of Alvin Plantinga released by Plantinga...

Alvin Plantinga - Image via Wikipedia

The discussion is interesting and well worth a listen. Although I think both sides could have made a stronger case. The moderation was mostly fair. However, I couldn’t help my bemusement that Plantinga was consistently ‘Plantinga; one of the world’s greatest philosophers of religion etc. ad infinitum‘ while Stephen Law had to make do with being just plain old ‘Stephen Law.’ I mean, sure, what do I know? Perhaps Plantinga just has these Übermensch qualifications to rival even The Stig while poor Law is inexorably left behind in the dust of mediocrity. But it did become increasingly comical in iteration as the show progressed.

The first part of the show was naturally dedicated to Plantinga explaining his argument. I shan’t explain it better than I already have. It’s a simple enough idea, and anyone with an urge for detail can listen to the show or read more about it online. The next part of the show was dedicated to Law’s questions, worries, and objections. Law – who by the way is currently relevant by having taken William Lane Craig up on his debating challange – started things off by questioning whether the probability of naturalistically evolved reliable cognition is truly as low as Plantinga thinks it is. It is entirely the right question to ask. Unfortunately, however, it led to an impasse very fast. Neither man was able to give any particularly persuasive arguments for their preferred probability assessments.

Image of Stephen Law

Stephen Law

On agreeing to move on, Law raised an issue, which could easily have been of particular relevance. I say ‘could have been’ because I feel Law dropped the ball somewhat. His worry was that even if we grant Plantinga his argument, it might just as equally lead to a defeater for theism as for naturalism. Plantinga’s theism entails an omnipotent divine creator with a desire to bestow upon us cognitive reliability. However, says Law, if our cognition then leads us to the conclusion that there is no such omnipotent divine creator, then we land ourselves yet again in murky waters. Unfortunately his chosen cognitive method of arriving at a no-God conclusion is the classic problem of evil, which Plantinga doesn’t find very persuasive anyway. I don’t necessarily find it as unpersuasive as Plantinga must, but I think it brings us somewhat far afield from the topic at hand. At the very least I think Law missed an excellent opportunity to bring Plantinga to task with a problem Plantinga seems to have created for himself.

The classic problem of evil is (roughly) that there seems to be an inconsistency between our actual world (it has evil/suffering) and the kind of world we should expect given an omnipotent, omniscient, and omni-benevolent creator. We can easily modify this argument to bring it closer to Plantinga’s home. There seems to be an inconsistency between our actual world, in that our cognition is massively and systematically unreliable, and the world we should expect given an omnipotent creator with a preference for cognitive reliability. We might call this ‘the problem of bias.’ I.e. whereas the problem of evil asked “If God has the ability, knowledge, and desire to prevent evil, whence then evil?” our modified version much more modestly asks “If God has the ability and desire to make humans cognitively reliable, why aren’t we?” This problem is far less easily brushed off by Plantinga than the classic problem of evil. (I should note that according to Wikipedia both Fitelson and Sober, and Ramsey have mentioned a similar problem for Plantinga. I haven’t read their papers, though, so I’m not in any way trying to do them justice.)

As a matter of interest I mentioned Plantinga’s argument to my biologist girlfriend. She scoffed at the argument and suggested the – to her obvious, but to me intriguing – solution that since Plantinga’s examples of adaptively beneficial yet ultimately false beliefs are highly circumstantial, it would probably be much more cost-efficient for our brains to have true beliefs. Sort of like our brain’s ability to learn chess by the simple rules of how each piece moves contrasted with our brain’s inability to learn chess by memorising each and every possible legal chess position by rote memory. (My example, not hers.)

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8 Responses to “Plantinga’s Naturalism Defeater”

  1. paul says:

    non-tech. comment.
    You are clear , but vast % of people are NOT
    The biases are unconscious,
    how define ‘ tendency ‘ ?
    – tend to………………. guess ?…. ignore ?…..
    …….rush?………… random response ?

    • I suspect tendency is just likelihood. So Paul has a tendency to promote humanism = The likelihood that Paul will promote humanism is at least greater than not. I might be wrong though.

  2. so… Al and Steve had an argument.. and they never reached a conclusion?
    so… Sketch and his disco GF came to a conclusion instead of them?

  3. That’s a really interesting argument. I agree – too bad they didn’t pursue it. It’s almost like the ontological argument turned on its head: It’s not that God must exist because he is conceivable (to simplify the argument insanely), but he cannot exist because his non-existence is conceivable. Pretty cool.

  4. John says:

    You really have to laugh when Plantinga is promoted as one of the worlds greatest philosophers of religion. when he essentially confines his “philosophy” to the usual dim-witted propositions of Christianity.

    What about the rest of the Great Traition of religious and Spiritual enquiry, especially as every possible Spiritual, religious and philosophical point of view that has ever been made by human beings is now freely available to anyone with an internet connection.

    Of course a similar criticism can be made of Stephen Law. Is he (and Plantinga too) thoroughly familar with the MANY very sophisticated philosophical propositions generated within the Hindu and Buddhist traditions.

    • I take your point. Western philosophy of religion does seem to have a Western bias. Although, I don’t think we ought to find that surprising or necessarily particularly benighted. Western literature degrees also have a bias toward Western literature, for instance. I think it’s simply a matter of cultural relevance, but I won’t deny that having our horizon broadened would be a good thing.

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