It is wrong everywhere, always, and for anyone to believe in any philosophical thesis

Given that equally smart philosophers disagree about almost everything, can a philosopher justifiably accept any philosophical thesis? Here is Peter van Inwagen's take on this issue:

"Well, I do believe these things. And I believe that I am justified in believing them. And I am confident that I am right. But how can I take these positions? I don't know. ... I suppose my best guess is that I enjoy some sort of philosophical insight ... And this would have to be an insight that is incommunicable

... 

I don't want to be forced into a position in which I can't see my way clear to accepting any philosophical thesis of any consequence. Let us call this unattractive position philosophical skepticism.

 ...

I think that any philosopher who does not wish to be a philosophical skeptic--I know of no philosopher who is a philosophical skeptic--must agree with me that this question has some good answer: whatever the reason, it must be possible for one to be justified in accepting a philosophical thesis" (Is It Wrong Everywhere, Always, and for Anyone to Believe Anything on Insufficient Evidence? 1996)

I have waded through a lot of philosophy and I have not found a single plausible philosophical thesis, unless scientism counts as one. A-theory or B-theory? There is no evidence either way. Internalism or externalism? Impossible to say. Humeanism or non-humeanism? I do not know, and neither does anyone else. Tropes or universals? I could care less.

I guess that makes me a "philosophical skeptic". There is no justification for any philosophical thesis because if there was, the justification would have to be empirical, and that in turn would make the thesis scientific, not philosophical.

This represents my view on justification:

"there is no such thing as a justifiable purely philosophical conclusion about any empirical phenomenon (and there are no such things as 'non-empirical phenomena'). Therefore, anyone who wants to defend a philosophical thesis had better be prepared to defend it as, in large part, a scientific proposition based on scientific evidence." (Don Ross et al: Midbrain Mutiny, 2008)