Recently I've been hearing the same line of thinking from a couple of sources - one from Sye, who has been patiently indulging in a little comment war here on my blog, and one from Rhology, who has been patiently indulging in little comment wars on his own blog.
This line of thinking has appeared to me to be circular and invalid, but Sye in particular has brought the point right to me: How do I know I can trust my reasoning and logic?
These gentlemen have postulated that unless there is a God, we cannot know that our reasoning and logic is trustworthy, because we have no foundation for them. Before I philosophize further, I want to examine that claim. It's a premise:
1. Unless there is a God, we cannot trust our reasoning and logic.
Essentially, it then goes like this:
2. We can trust our reasoning and logic
3. Therefore, God exists.
Yes, it begs the question. If we accept Premise 1, when we are approached with Premise 2 we are free to say 'Uh uh uh, can we? You haven't yet proved that God exists. Until you've reasoned that God exists, I apparently can't trust your ability to reason that God exists...'
The real question at hand
is Premise 2. Can we trust our reasoning and logic? If Premise 1 is true, then we cannot know if Premise 1 is true, and we thus cannot use Premise 1 to lead into Premise 2.
The only way we can know whether or not Premise 1 is true is if Premise 1 is, in fact, false.
That's because it takes reasoning to come to the conclusion of Premise 1. Only if you can trust your reasoning without there being a God can you come to the conclusion that only if a God exists can you trust your reasoning. It's a mess.
The issue here, as the title of the post indicates, is justifying beliefs. Doing this, one often runs into the problem of an infinite regress: I know it's Thursday because yesterday was Wednesday, which I know because the day before was Tuesday, ad infinitum.
Typically, there are three options for attempting to justify beliefs. The first is that there is an infinite regress, as described above, which is incapable of actually justifying anything. The second is foundationalism. Foundationalists believe that this infinite regress is halted when it settles upon a belief that is justified without being justified by other beliefs. The third option is that beliefs are simply justified by other beliefs which are, in turn, justified by others in a circular fashion - and circular reasoning is, of course, incapable of justifying a belief (as I hope Sye and Rhology realize at some point).
Coherentism is usually represented metaphorically as a web of beliefs, which is made strong and self-supporting by the relationship each belief has with the other beliefs, all of which are tied together.
I have to thank Sye for bringing up the issue. My core beliefs are brought into question practically every day, and I am quite often made to doubt them - or, at least, to strongly reconsider them - and I have to read up on or think about them with a great deal of concern.
I hadn't previously thought about how I justified my trust in human reasoning and logic. My first reaction was 'well, it corresponds to reality.' Truth is, it's a little something more. If I must use logic and reasoning to justify logic and reasoning, have I not engaged in circular reasoning? If I must start with the reasoned premise that God must exist for reasoning to exist, have I not begged the very question?
I trust my perception of reality. I trust it because it forms a very coherent web. No one belief has to lean on another in a linear fashion - they work together holistically. I am an empiricist through and through, so I believe that what we perceive as real is what is really real. I also trust what reliable people have observed under reliable circumstances. These observations begin to form a web, part of which is that logic and reasoning conform to reality, and that illogic and unreasoning does not. These beliefs and observations are tied to the observations others have made. Overall, it makes a web coherent enough that I am willing to let it support my weight.
When a little fly catapults into my web and destroys a strand or two, I'll just have to rush over and try to repair or replace the strands. I think that's all we can do.