1) A "small" sample is often sufficient reason to accept a statement. If I tell you that there exists a Turing machine that can solve SAT in polynomial time, all I have to do to prove it is supply one (incidentally, if you have one lying around, let me know :P ). If I tell you that ALL of something is bad, then I have an uphill battle. But if I tell you SOME of something is bad, I only have to provide a single example to be right.

Also, you may want to read PG's essay on essays (www.paulgraham.com/essay.html); his goal in writing an essay isn't to explicate every detail of a subject, it's to work through a subject to understand it--it is only tangentially that any other audience is involved. That I am convinced of the rough truth of his arguments is not solely based on what he has written, and he does not have to personally supply me with every bit of evidence to be right (although doing so would certainly make it easier for the reader).

2) I would not question the fact that Greek philosophers influenced the development of mathematics, and I expect PG would not do so, either (particularly since the Greek philosophers were typically also mathematicians, but even without that, it would seem an impossible claim to the contrary). A claim I have made, however, is that the things that the Greek philosophers wrote that could not now be seen as important in some other field currently extant, or in cognitive science--which ought to be thought of as its own field (although in many places it isn't yet)--were not themselves important to the development of mathematics or any other field. These aspects of their writing, when studied, critiqued, and emulated in modern times, are the only topic of concern to PG in his essay, or myself in this particular discussion.

3) This is a fundamental problem. Just because we disagree certainly does not make one of us right, and the only reason that at least one of us is guaranteed to be wrong about something here is because I just asserted that we disagree. An equally fundamental problem is your assumption that either PG or myself is talking about all of philosophy.

With regard to "strange" ideas, every field has had strange ideas when looking in hindsight. The fields for which those ideas are still in contention for validity are the ones with the greatest problem of lack of substance, in proportion with how many such ideas there are, and how "strange" they are (where by strange I do not mean counterintuitive, but rather running against other existing evidence).

4) Relatively little thinking. We got a lot better at it when we didn't have to spend most of our time hunting and gathering. The course of human history has been the process of freeing up more time to spend thinking; at this point, we've freed up so much that we tend to use most of it in ways we typically later label as non-productive.

You say you can do this for all fields. Can you point to some bad math for me? That you would have much greater difficulty doing this than PG or I would have for finding bad philosophy is precisely PG's point.

Is there some other form of argument that could possibly exist to support his claim other than personal experience and selected examples? I'm not sure what kind of evidence you would like to see in PG's essay, but feel it lacks. The subject matter does not lend itself to effective experimental testing, and the claim is not mathematical in nature.

PG's, and my, problem, is that modern philosophers still rarely identify the fact that the bad thinking is bad. Understanding the utility of (and the utility of understanding) effective but civil critical debate remains unquestioned. The subject matter of these debates is what is under fire here, precisely because it is typically pervaded by faulty reasoning. Even if you want to use previous bad reasoning to learn why some reasoning is bad, this doesn't mean you need to continually create more examples of bad reasoning; surely those that already exist suffice.