A logical argument has propositions or axioms which are assumed to be true. It then has logical statements/manipulations which, if all valid, reach a logically valid conclusion.
If the argument is logically valid, then we can say that the conclusion is true if all the propositions are true. However, the logical validity of the argument says nothing whatsoever (and cannot) about the truth of the propositions. They are simply accepted as true for the exercise of evaluating the logical validity of the argument.
It would seem to me that all a philosopher can truly do is determine if a philosophical or metaphysical school of thought is logically valid or not. And adopt, or not, a given school based on your acceptance of the evidence for its propositions.
One can never get to the ultimate truth of any of its propositions, and therefore, can never address the ultimate truth of any of its conclusions. One can only determine whether a given philosophical school of thought / logical framework / worldview is a logically valid paradigm with which to view the world - that is logically consistent within itself.
For example, as we perceive that the world is more complex than our mind - as we experience our minds - virtually all people accept that solipsism is false based on their own personal experience of reality, but no one has been able to prove (nor do I believe anyone can prove) that solipsism is false. It can be called "trivial", but not false.
This is illustrated by the conclusion of Dr. Kelly James Clark, in an Essay in which he argues - to the best of my understanding, that belief in God can simply be accepted as a propositional truth, without needing any evidence for it (emphasis added below). His reasoning ultimately is not that there is no evidence for the propositions of the existence of God, but that completely rational people using completely rational reasoning, just plain end up disagreeing on which philosophic system is correct, and no propositional belief can be fully proven. Neither person is "wrong" from a philosophic standpoint. All primary beliefs are based to some measure, on faith.
My point is not to make people skeptics. Rather it is my intention to demonstrate the obvious truth that rational people rationally disagree. What people start with determines what people will end up with. What people reason from determines the kinds of inferences that it is rationally permissible for them to accept. There simply is no belief-neutral, obvious and simple foundation of beliefs to which to appeal in arguing for the existence of God.
(Dr. Kelly James Clark, Without Evidence or Argument: A Defense of Reformed Epistemology)
