Before the development of empirical natural sciences starting* with Galileo, we (the West) were pretty confused about truth, knowledge and ethics. After Galileo, it took us a few hundred years to figure out the scientific method** and get to the Industrial Revolution.
*More or less; the thread of every philosophy can be traced to the earliest writings; it's arguable that empiricism and naturalism start with Thales, one of the earliest pre-Socratic philosophers whose writings have survived.
**You have to look at the scientists and engineers; philosophers didn't catch on until Popper in the mid-20th century.
With the Industrial Revolution, we were confident that we had figured out truth and knowledge. We naturally figured that the truth of our
***Irony: These two apparently trivial problems demolished not only classical Newtonian physics but also the absolute truth of Euclidean geometry and the notion of synthetic a priori truths.
Human beings are naturally authoritarian-submissive (see Altemeyer, Milgram and Zimbardo). The Enlightenment rejected scriptural and personal authority, embodied in the Bible and the Church, and cast about for a new authority. The authority of science and reason seemed like a likely candidate. It's useful and no more arbitrary than any other scheme to label as "modernism" the position that Enlightenment values were the best (or nearly the best) way of living, by virtue of being objectively, scientifically true.
The first World War put paid to such naive notions; the second put the nails in the coffin. Both world wars were entirely intramural struggles: Russia and Japan got into the act by virtue of Westernizing. (Need I mention that Marx was a German?) Two generations of killing off millions of one's own people, mostly children, pretty much demolished the naive notion that "Enlightenment values" were even close to the apex of ethics.
Modernism, even the modernist notions of the One True Physics, was beset on all sides, including Quantum Mechanics and the problem of the observer, underdetermination, and severe difficulties with ontological reductionism. If we couldn't even come up with One True Physics, we were completely screwed on One True Ethics.
So postmodernism comes on the scene. I separate the school into "good" postmodernism (I consider myself a good postmodernist) and "bullshit" postmodernism. Good postmodernism just weakens our notion of truth: There is no One True Anything, but given some point of view there are truths and falsehoods. Bullshit postmodernism, on the other hand, appears to make truth a matter of pure subjective relativism: Everyone has his or her own truth, just as "valid" as anyone else's.
But we can't just dismiss truth so blithely. If you and I don't mean the same thing at least about something it's hard**** to say that we're communicating. It's arguable that much of bullshit postmodernism is not in any way communicative, but a lot of it actually seems communicative, so there must be some notion of "true for everyone" in there.
As authoritarian-submissive as we are, we still want the authority of some true for everyone, any truth, to underlie our ethical beliefs. It's a very scary thing—even for many atheists—to admit that we're simply on our own regarding ethics. There is no God, no Daddy, not even the Universe, that can determine our choices. We're suspended above the abyss of ethics with no net of truth.
In a sense, bullshit postmodernism is regressive: It brings truth back to the pre-modernist, pre-Enlightenment domain of subjectivity and the power to impose one's subjectivity on others. The postmodernists do a better job than the religious of hiding this personal authoritarianism, but it's still there.
Two styles of argument mark out bullshit postmodernism. The first:
- All positions are true for the speaker
- My position is true for me
- My position is true
- Your position is different from mine
- Your position is therefore false
- All positions are true for the speaker
- Your position is true for you
- But to assert your position is true is to assert it's true for everyone
- No position is true for anyone
- Therefore your position is false and mine is true
The amusing thing about bullshit postmodernism is that it establishes only the personal authority of the academic humanities community. But these people are utterly inept at actually exercising this authority in any meaningful way. They can dominate and oppress a bunch of eight-year-olds, and pass the occasional stupid law, but otherwise we have little to fear from humanities academics. They might bore us to death, but they won't actually shoot anyone.
The good postmodernist simply recognizes that there are small-tee truths about how people actually are, what they actually approve of, disapprove of, admire, condemn, and desire, and that the laws and customs of a society are expressions of statistical properties of those beliefs. Some of those subjective beliefs, and their expression in law and custom will have positive (e.g. the strongest economy in the world, at least pre-Bush) or negative (a half trillion dollars not only wasted in Iraq but put in the service of appalling human suffering) effects in reality; some will have no direct effect (e.g. Christmas, Eid, Cinco de Mayo).