Scholarship is excellent, but it is also expensive. It takes a long time to catch up to the state of the art, even for a narrow subject.
I recently read 90% of the literature on machine ethics, a recent and small field of inquiry, and it took me about 40 hours to find all the literature, acquire it, and read (or skim) through it. Doing the same thing for an older and larger subject will take far more time than that. And of course most of the literature on any subject is not valuable.
Other times, you get lucky. Let's say you want to figure out how to beat procrastination. You could introspect your way to a plausible solution, but you might end up being wrong. So, you check Wikipedia. Not very useful. Next, you search Google Scholar for "procrastination." An article on the first page looks like what you want: an overview of the scientific research on procrastination. It's called "The nature of procrastination: A meta-analytic and theoretical review of quintessential self-regulatory failure," and it's available online! As it turns out, you can do a pretty decent job of catching up on the science of procrastination just by reading one article. (Of course it's not that easy. You should be more thorough, and explore alternate perspectives. Psychology is not settled chemistry.)
And in machine ethics, it turns out that most of what you'd want to know is summarized nicely in a single book: Moral Machines (2009).
But on other topics, you won't be so lucky. Suppose you want to study the neuroscience of how desire works. You check Wikipedia, and it has a section on the psychology and neurology of desire. But it doesn't tell you much. A Google Scholar search is even worse. You check the index of a large neuroscience textbook for "desire," and come up with basically nothing. The Stanford Encyclopedia of Philosophy article on desire is pretty good, but it barely touches on neuroscience. It does point you to two good resources, though: the book Three Faces of Desire, which sounds like it will cover the neuroscience, and the work of neuroscientist Kent Berridge. Now, because I have studied the neuroscience of desire, let me spoil the surprise at this point: this research project is not going to be so easy. You have a very long "literature slog" ahead of you.
So I won't argue that scholarship is always or even usually the instrumentally rational thing to do when you want to make progress on a certain problem. Sometimes the costs of scholarship outweigh the benefits.
But to make that judgment, it will help to know just what those costs and benefits are.
Some Costs of Scholarship
1. Scholarship takes time and effort.
This is the biggie. Scholarship takes time. Especially if you don't have much experience with it already. Resources like Google Scholar make it easier than ever, but scholarship still requires lots of patience and perseverance and procrastination-mastering.
2. Opportunity cost.
The fact that scholarship takes up time means that while you're doing scholarship, you're not doing something else that might be more productive. Scholarship can even serve as a form of procrastination, reading things just because they're on your to-read list so that you can avoid doing something else. [thanks taryneast]
3. Studying some subjects can weaken or corrupt you.
Without (and maybe even with) rationality training, studying certain subjects will make you dumber. To me, postmodernism and even most analytic philosophy look like a good candidates for stupid-making subjects of study. Other candidates include theology, literary theory, and scripture scholarship. These fields can teach bad modes of thinking, false "facts", and even absurdities. Luckily, there are some heuristics you can use to estimate the value of a field.
4. Some things cost money.
I've spent quite a bit of money on scholarship: on gas for trips to a university library so I can download papers from behind the paywall, on hard drives to store tens of thousands of PDFs, on books purchased from Amazon, and so on.
5. Scholarship can be a shiny distraction.
A long list of footnotes and references might be built up to conceal the fact that the ideas in an article or book are of little value. [thanks Perplexed]
Some Benefits of Scholarship
1. You'll avoid some mistakes and confusions.
Suppose you were about to argue, with Jeremy Bentham, that all intentional human action aims at pleasure. Doing some research on the neuroscience of intentional action would help you avoid that mistake. As it turns out, it's just not true that all intentional human action aims at pleasure. Pleasure is only one goal among many.
Scholarship can also help you avoid confusions, for example between two kinds of intrinsic value.
2. You'll learn to speak the same language as everyone else, and thus communicate more effectively.
When you read other works on the topic you're discussing, you discover the established terms already used for discussing that topic, and you can begin to speak the same language as everybody else.
3. If your rationality skills are sharp, you'll become generally smarter and wiser.
If you're equipped to recognize magical categories and mysterious answers, consuming a diverse array of fields can give you a broad, integrative kind of knowledge. But be especially wary of subjects that can make you stupid, like postmodern philosophy.
4. You won't waste time re-stating what has already been said elsewhere, better and more knowledgeably than you can.
Many times, I've decided I want to write about X. So then I start researching X to prepare for writing. Then I discover that somebody wrote an article that says everything I wanted to say about X, but they've been studying X for ten years and really know their stuff. Then all I have to do is type two paragraphs about it and link to it on my blog. Hurray!
5. You'll be taken seriously by more people, and have more access to useful experts.
Researching your topic and citing the relevant literature are pre-requisites for some activities like academic publishing, which can get more people to take you seriously because you've put forth the effort to pass a basic test of quality: peer-review. Really smart and accomplished people have too much to read already, and most of them are unlikely to read what you've written if you haven't even bothered to pass peer review.
And, the more smart people take you seriously and read your stuff, the more brain power you can call upon in solving the problems you care about.
6. You'll avoid the tendency to over-trust bearers of good info.
Especially when approaching a subject for the first time, you might read something so bloody intelligent that your mind can't help but cast a halo around its author and accept whatever he or she said. But continuing with your scholarship, and reading lots of people who agree and disagree with that author, can help you see him or her as part of a large enterprise that has been struggling on certain problems for a long time, and may expose you to data that disproves claims made by the original author that impressed you.
Conclusion
Nobody on Less Wrong should be fooled by the fact that I listed more benefits than costs for scholarship. That doesn't mean scholarship is always a good idea. Often, it's not a good idea.
But having a list of costs and benefits can help you decide whether scholarship is worthwhile for a particular project - or, how much scholarship is worthwhile.
Now, what did I miss?
I'd delight in telling you you're wrong, but you're mostly not.
I would say that I don't think that postmodernism is lacking in rigor. Certainly, having been on both ends of peer review in the humanities, it does not seem to me that the process lets through a lot of flamingly inaccurate crap, beyond the sort of expected problems you get in the margins of well-studied ground. Frankly, in my own research, I'd have an easier time sailing a howler about the history of video games past peer review than I would a howler about the applications of Derrida.
I'm also not sure it does as badly as you say on Vladimir M's heuristics. Looking quickly, for my own field, there's still a ton of low-hanging fruit. Yeah, the major canonical works of literature assigned to undergraduates are pretty well-covered in the literature, but if you're working in popular culture of any era, you have basically no excuse for running out of things to say. The ideology test is a little trickier, since there are areas of literary criticism - feminist, queer, and racial studies, most obviously - that are explicitly ideological. But, of course, we have to be careful with ideology as a warning sign, because arguably at this point climate science and biology are ideologically poisoned. Ideology takes place heavily outside of the academy, and I'm loathe to say that just because something has become a political hot potato the academics of it are prima facia problematic.
But I think that postmodernism, broadly speaking, also hedges well against ideological bias. The thing that it is most easy to completely miss about postmodernism is that it is, by and large, a study of epistemologies. Yes, postmodernist literary criticism makes massive use of Freudian psychoanalysis despite the complete discrediting of Freudianism as an empirical practice. But we don't psychoanalyze real people. We psychoanalyze fictional people. The question is not "does there exist a real person with an Oedipus complex," it's "is the Oedipus complex a sufficiently well-known concept that it would be either included in a work of fiction by an author or read into a work of fiction by a reader?" In other words, since we're generally dealing with man-made structures, the question is less "Is foo true" and more "Is foo part of what is talked about and thought about regarding this subject?"
This helps a lot with the ideological bias issue, because it means that postmodernism can actually be ideologically neutral on the political issues it seemingly invests in. This is something I tell my students whenever one of them gets fussy about the fact that I assign literature with gay people in it. You don't actually have to accept the premise "homosexuality is not a valid basis for discrimination" in order to understand how gay writers articulate their own experience in literature.
Now, in practice, of course, literary scholars are generally liberals who are supportive of gay rights, feminism, and further work towards racial and economic equality. But then again, the ideological bias in the academy extends far beyond humanities departments - it's increasingly hard for an American climate scientist to be a Republican too. At the end of the day, this is somewhat irreducible - after all, reality probably does, in the long run, lend more support to some political viewpoints than others.
In any case, I tend to think that postmodernism is something that just about everybody should be broadly familiar with. I think there are some serious problems with how we teach it, and some serious problems with how it's attacked (Alan Sokal should never, ever be referenced by anyone who is trying to make a serious point about humanities scholarship. His "research" on postmodernism makes his hoax article look like sound scholarship by comparison), but the basic elevator summary of postmodernism is "It's the process of learning to account for epistemological differences when dealing with communications." Which is something that is probably useful if, you know, you ever intend to talk to someone you disagree with in your life.
Also, can I just say that the Stanford Encyclopedia entry you linked to is absolutely terribly written? Clue for writers explaining concepts that use algebraic or pseudo-algebraic notation - it's really nice if you bother to define what S and T mean before you start throwing them around.
Actually, one of my major objections to the modern intellectual currents that are commonly called "postmodernist" is their bias -- part ideological, part fashion-induced -- in choosing which authors to consider as classics and standard sources of citations and inspiration. We keep seeing an endless stream of discussions using concepts from Marx, Freud, and others whose work has long been shown to be largely bunk (even if later authors have salvaged some... (read more)