It's a reasonable question. First, I think that the linked example is not the best of post-modern thought.
More importantly, a lot of post-modern thought is co-opted and the label is forcibly excised. Here are some examples of what I think are good post-modern ideas.
There was a tendency for colonist-era Europeans to ascribe exotic virtues to Near and Far Easterners that had little relationship to the values of those communities. Orientalism is a discussion of this dynamic related to Near Eastern culture. I don't think the dynamic can be well explained by reference to in-group/out-group, but post-modernism does a good job, in my view. Consider also the phenomena of the Magical Negro (warning: TVtropes)
Death of the Author (TVtropes), the view that the author's opinions do not control a work's interpretations, is also heavily influenced by post-modern thought (or so I understand - I'm not very interested in most lit crit of any flavor)
The slogan "The personal is political" is insightful because it highlights that "political" (i.e. partisan electioneering) is not really a natural kind in political-theory conceptspace. Issues of personal identity are just as mindkilling, for essentially the same reasons. Also, post-modern theory helps explain why the legal distinction between public action and private action is not well defined in practice.
Also, post-modernism is often intentionally filled with hyperbole. For example, I'm persuaded that Nietzsche was not anti-semetic or fascist, but reading Geneology of Morals literally can easily leave that impression. There are reasonable methodological arguments about whether hyperbole is a good idea, but post-modernism is usually on the side of more hyperbole (in part because colloquial usage often does not encompass a natural kind).
Finally, post-modernism is closely clustered with anti-capitalism and anti-empiricism. I can't defend this association, but it exists. I think much of the perceived poor quality of post-modern thought is really disagreement with those other positions. I don't think those positions are an essential part of post-modern thought - for example, I think Foucault is trying to be a high quality historian. If I were persuaded that his history was bad, that would necessarily cast doubt on his conclusions from the historical evidence.
Thank you for this.
It's funny you should mention Death of the Author. I have another friend whose academic background is in literature, and he rants to the point of blind fury about how ridiculous a notion it is. I showed him the above link to get his opinion, and his most pointed comment was how the author's emphasis on academia, student debt and being forced to work menial academic positions was not a shining indictment of Roland Barthes.
A month or so ago I stumbled across this. It's a blog piece by one Robert Lanza M.D., a legitimate, respected biologist who has made important contributions to tissue engineering, cloning and stem cell research. In his spare time, he is a crackpot.
I know I shouldn't give any of my time to an online pop-psychology magazine which has "Find a Therapist" as the second option on its navigation bar, but the piece in question could have been *designed* to antagonise a LessWrong reader: horrible misapplication of quantum physics, worshipful treatment of the mysterious, making a big deal over easily dissolvable questions, bold and unsubstantiated claims about physics and consciousness... the list goes on. I'm generally past the point in my life where ranting at people who are wrong on the internet holds any appeal, but this particular item got my goat to the point where I had to go and get my goat back.
If reading LW all these years has done anything, it's trained me to take apart that post without even thinking, so (and I'm not proud of this), I wrote a short seven-point response in the comments lucidly explaining its most obvious problems, and signed it Summer Glau. It got removed, and I learned a valuable lesson about productively channeling my anger.
But this started me thinking about how certain things (either subjects or people) antagonise what I now think of as my LessWrong Parts, or more generally cause me distress on an epistemic level, and what my subjective experience of that distress is like so I can recognise and deal with it in future.
I've seen a few other people make comments describing this kind of distress, (this description of "being forced to use your nicely sharpened tools on a task that would destroy them" seems particularly accurate). Common culprits seem to be critical theory, postmodernism and bad philosophy. I've also noticed some people distress me in this fashion, in a way I'm still struggling to characterise.
Who else has this experience? Do you have any choice examples? What hurts you in your LessWrong Parts?