When I wrote "Beyond Simple Acceptance," I made a note that "I employ the terms "modernist" and 'postmodernist' as I discovered them in The Truth About the Truth, edited by Walter Truett Anderson." In retrospect, I realize this is entirely unfair to you since this is not an easy book to find and you cannot know how I'm using my terms without finding and reading it. (To be fair to myself, I did not expect quite so many people to read that post.) So I will try to define my terms.
I want to note, very strenuously, that I am not really postmodernist. I was merely borrowing the terms "postmodernist" and "modernist" from postmodernism because they are available to me and I thought the distinction between them would be a fruitful way of framing my position.
Before we begin, I will recommend that you read my original posts (the first is here: link) about postmodernism. They are ~3 years old and my understanding has changed somewhat, but they are nonetheless serviceable. For the purposes of this post, I will not assume that you've read them.
Postmodernism tends to position itself as the last of a three-part movement in epistemological history, defined around modernism: first, there is premodernism; second, there is modernism; third, there is postmodernism.* However, there are really two ways of thinking about these concepts. One of these is as groupings of philosophical movements, which is how most people think of postmodernism, but the other way is to think of them as the mode of a culture during a particular epoch, so the distinction is between premodernity, modernity, and postmodernity. I will address the modes first, and then the movements.
In premodern societies (or premodernity), people lived in complete, unchallenged worldviews. Everyone you knew believed the same thing, and it was probable that you did not even really know that there were people who believed different things than you did. If you did know of such people, it was easy to dismiss them. There was no culture shock.
In modern societies (or modernity), people were aware that there were multiple worldviews. Since your worldview was the correct one, you tried to get everyone to join that worldview by some method or another. You were engaged in a struggle of conversion, and your society was beset with culture shock.
In postmodern societies (or postmodernity), people have come to realize that their own worldviews will never be shared by all people. Your worldview might be the correct one, but you'll never convince your neighbour of that. And you know many people for whom this sort of situation, a permeation of culture shock throughout all of our lives, is not really so bad after all.
Anderson, in the book's introduction, summarizes it like this:
People in premodern, traditional societies had an experience of universality but no concept of it. They could get through their days and lives without encountering other people with entirely different worldviews--and, consequently, they didn't have to worry a lot about how to deal with pluralism. People in modern civilization have had a concept of universality--based on the hope (or fear) that some genius, messiah or tyrant would figure out how to get everybody on the same page--but no experience of it. [...] Now, in the postmodern era, the very concept of universality is, as the deconstructionists say, "put into question." [...] It begins to look like we're all going to have to get used to a world of multiple realities (6).Bear this in mind when we're talking about the movements, because in a sense the movements are about what kind of cultural mode you think you are living in (though I find it very hard to believe anyone could fail to recognize that we live in an intractably pluralist world now).
In his essay "Four Different Ways to Be Absolutely Right," Anderson traces out four worldviews based on where people locate truth.
The postmodern-ironist believes that truth is socially constructed.
The scientific-rationalist, a modernist, believes that truth is found through methodological inquiry.
The social-traditionalist, also a modernist, believes that truth is carried through the heritage of Western civilization.
The neo-romantic, a retro-premodernist, believes that truth is found through harmony with nature and/or exploration of the inner self. (111)
Now of course there are different varieties of each. The social-traditional worldview includes forms of nationalism, revealed religion, and philosophically- and aesthetically-inclined atheisms. Neo-romantics include radical environmentalists, New Age proponents, and so-called "California Buddhists." Postmodern-ironist movements include constructivists (who are more philosophically-inclined and choose to live a particular folkway rather than reject all or mix-and-match), postmodern players (who don't take much interest in abstract ideas of postmodernism and whose irony is more attitude and lifestyle than philosophical position), and nihilists (who believe that since all possible worldviews cannot be simultaneously true, none of them can be) (111-112).
My summary of Anderson's ideas and ideas from the many essays Anderson includes in the book, in a very simple form, is roughly as follows:
A modernist believes not only that there is an objective truth, but also that it is accessible to all people and you can, within reason, expect other people to access that objective truth the way you do. Different modernists locate this truth in different places--a religion's tradition, a religion's central administration, a sacred text, scientific inquiry, Western philosophy's tradition and method, a country's Constitution/Charter/Bill of Rights or legal code, an aesthetic work or movement, an economic system--but they all have a master story, what postmodernists call a metanarrative, about where the truth can be found and what that means for everybody else.
A postmodernist believes that no one can directly access any objective reality, and that all truth-claims are necessarily constructed. (Either "the map is not the territory" or "the map precedes the territory," depending on your postmodernist.) Sometimes, they believe that there is no objective reality, but that's not usually the case. Postmodernists reject, or at least are suspicious of, metanarratives; there is no master story to which all other stories must capitulate. You cannot expect other people to construct all of the same truths that you do (but there are some truth-claims that you can expect them not to construct, usually ones that essentialize people according to gender or ethnicity etc.).
So that's how I'm using those terms. I don't actually subscribe to the postmodernist story of intellectual history, or at least I recognize that it only applies to European and North American intellectual history. But, as I said, I find the distinction between the two positions fruitful.
(For what it's worth, I don't consider myself as taking part in either position, not exactly. If I were Hegelian, I might say that where modernism is the thesis and postmodernism is the antithesis, my beliefs are the synthesis. But I'm not Hegelian. I do think most postmodernisms are bound to fail--they make their own metanarratives, after all--but also that postmodern critiques of most modernisms are fatal. I would say that anyone who doesn't take postmodernism seriously, and doesn't adjust their modernism into something that is no longer quite modernism, is underestimating postmodernism's claims. But postmodernism isn't the place to stop, either.)
*I intend to commit the sin of reification. I'm going to talk about postmodernism as though it were an agent. It isn't, obviously; postmodernists are agents, but postmodernism isn't. But it's so much easier to attribute stuff to postmodernism because it's hard to find any one postmodernist who says all of these things.