Defeaters

Undercutting: where E is evidence for H, an undercutting defeater is evidence which undermines the evidential connection between E and H. 

Rebutting: is evidence which prevents E from justifying belief in H by supporting not-H in a more direct way. 

In general:
a. Moving from believing that p to believing that not p requires a rebutting defeater

b. Moving from believing that p to not believing that p requires an undercutting defeater

Note the difference between the scope of the 'not' in a. and the scope of the 'not' in b. In a. one believes something, namely, not p. In b. one does not believe something. The 'not' in b. is negating the believing, whereas the 'not' in a. is negating the thing that is believed. 

Ok, given all of that, you should be able to explain the relevance of the following cases that Plantinga brings up in Chapter 6. Are they examples of undercutting or rebutting defeaters? How does Plantinga use these cases to show that the conflict between Simonian science (evolutionary psychology and some versions of HBC) and religion is superficial at best?

Here are the cases:

The Sheep Case
The Cacti Case
The Barn Case
The National Enquirer Case
The Twins Case
The Mall Case
The Truncated Physics Case
The Slashing Tires Case

Comments

  1. UnknownApril 12, 2019 at 10:40 AM

    With regard to the sheep case, I think what Plantinga is saying is that MN isn't actually providing an undercutting defeater for Christianity because it assumes different evidence bases. It only shows that PART of a Christian's beliefs are improbable or unlikely. Therefore, there is no defeater for Christianity until people assume the same evidence bases.
    -Ben

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    Replies
    1. David AlexanderApril 15, 2019 at 3:47 PM

      Good. But you need to state the point a bit differently to make it clear. His point is not that it only shows that PART of a xians beliefs are improbable. His point is rather that a xians beliefs are improbable on a PART of the evidence base of xians. But they are not improbable on the whole evidence base of xians. So, restricting the evidence base, gets improbability of xian beliefs, but that is uninteresting. Why? Because restricting the evidence base of anyone gets improbability of all sorts of claims that are super probable on unrestricted evidence bases. For example, that my name is 'David' is improbable if we take away from my evidence base anything that implies that my name is 'David.' But once we expand the evidence base to include, say, by parents calling me 'David', my birth certificate and so one, it is now highly probable that my name is 'David.

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