Richard Carrier has taken the time to write a detailed reply to my criticisms of his epistemology. Here is my reply to him:
Richard argues that simple deductions do not require memory, and in this he is probably correct. However, the really important reasonings that we go through tend to require several steps, so skepticism about memory would be quite damaging to them. For this reason, I do not see any way to escape the conclusion that we must assume the general reliability of memory in order to reason. Contra this position, Richard says, "If that were the case, we could never identify a false or inaccurate memory." The problem here is that we cannot even identify false memory without a broader trust that memory is, in general, reliable. For example, if I am ever in a situation where I must testify in a criminal trial, I know I would do considerable worrying about remembering the events accurately, but only because I have memories of forgetting things, of comparing family anecdotes and the people involved remember the event differently, and reading about psychological data on this issue.
Indubitable perceptions and the outside world
Again, I agree with Richard that immediate experience is indubitable. The problem is he has provided no indubitable (his standard) reason to think that our experience of apparent physical objects is reason to think those objects exist. At one point, Carrier seems to suggest that the way they cohere with eachother provides such a reason, but this just puts the problem back a step. What is the indubitable source of the claim that the coherence of our peceptions (with eachother) is reason to think that they match some external world?
The problem of circularity
Richard says that "we always end up in some circular argument, a fact even Platinga admits of his own, and in fact every conceivable epistemology." This is a strange statement from someone who thinks we can believe nothing without justification. Traditionally, it has been recognized that a circular justification is no justification at all. Epistemically, it is just as problematic as an infinite regress of justifications, and in fact can be seen as such an infinite regress.
In the interest of interpretive charity, I should say it is possible that Richard is here equating circularity with the incorrigibility of immediate experience. If so, he avoids the above problem. However, this reading does not seem very plausible, though he may tell me otherwise.
The solution to the problem
In my original posts, I argued that Plantiga's epistemology, or something like it, is the only real solution to the problems under disucussion. And when talking about Plantinga's epistemology, I do not think Rihard is correct to say that Plantinga's solution is "Simply to assume Christian Theism is true, and that we are fully justified in assuming this without needing any evidence Christian Theism is true." He appeals to his epistemology to defend Christianity, but it does not seem to be a central feature of his epistemology. Rather, I take the important claim to be that non-indubitable beliefs can be taken as properly basic.
Now, Richard asks, what criterion would I set for proper basicallity? A tempting solution would list the properly basic beliefs as follows:
1) Our senses are generally reliable
2) Our memory is generally reliable
3) Our notions of rational inference are generally reliable
I must emphasize that begining with the general reliability of these things does not mean we cannot refine them over time. Indeed, we can learn when our senses and memory are likely to fail us, as well as discarding bad principles of reasoning for better ones. But this has to be a process of sucessive refinement from what we already have.
My one doubt about the three point system above is that many people are more attached to specific beliefs than to abstract principles of reasoning. Ask the average person on the street their opinion of falsifiablism and they're likely to give you a funny look. Ask them if it's reasonable to believe in an Invisible Pink Unicorn... well, okay, they'll give you a funny look, but they will also have no problem saying that the answer is "no." We develop countless beliefs about the world before working out any complex principles of sound inference. To work out such principles, we often need apparently clear cases whose basis in specific principles of inference is not so clear.
The end result, which will no double seem counter-intuitive to many, is that there are no a priori limits on what can be believed without justification. This may put us in the position of believing falsehoods without evidence, but I don't see a good way around it. What we can do is make a commitment to weeding out mistaken beliefs, and I think we must do this given the countless known cases of mistaken belief in the world. Part of this is trying to formulate general principles of reasonable belief, of how we can trace back common sense beliefs to evidence, starting with the clear cases and working down to the less clear ones. When we do this, I think, we find that it is a mistake to believe specific claims about the external world without reason. But we cannot derive this conclusion a priori, nor can we demand reason for many other sorts of beliefs without running into the classic problems of epistemology.
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