Let me begin by clarifying that I don't intend this defense of modernity to extend to every ideal, precept, or especially consequence of modernity. Indeed, many of those I find deplorable, inane or undesirable in various respects. This particular defense is only of the epistemological sort. My assertion is that, contrary to the movement in epistemology toward postmodernism, there is nothing wrong with modernity's scientific rationalism and verificationism, such as it is.
The perceived flaw in modernity's epistemology is largely just that; a (mis)perception. The central 'revolutionary' contribution of postmodernism to epistemology, which is supposed to wholly undercut modernity, is essentially the idea that modernity's scientific rationalism itself is built upon various unverifiable (and unfalsifiable) presuppositions and contingencies. Therefore, if the most 'objective' and 'rational' system of verification is itself not inherently rational or subject to verification, then verificationism as a whole must be without merit or import.
Presented in this way this argument reads very much like a modern rejection of modernity itself. Which is to say that postmodernism seeks to undercut modern epistemology using modern epistemology. Or, put another way: "There's no way to truly know anything, but we know modernity is wrong." Thereby reducing the contributions of postmodernism to nonsense.
Ignoring this irony for a moment, there is a problem with the argument itself. The premises are indeed all quite true, but the conclusion does not follow from those premises. Which is to say that modernity already understood the epistemological qualifications that postmodernism supposedly brought to light, and modernity had already fully accounted for and integrated these qualifications into it's systems of verification. At no point did modernity operate under the pretense that scientific rationalism necessarily revealed absolute truth (although many modern men may have), rather only that it could verify or falsify particular truths given a specific set of presuppositions, and operating within a particular framework. Thus postmodernism has contributed nothing to epistemology that modernity, properly understood, didn't already adequately incorporate within itself.
That doesn't mean that all conclusions of modernity are absolutely valid. On the contrary, modernism recognizes it's inherent limits. Limits that the postmodern movement arrogantly, and errantly, believes that it's exposing. Certainly any who took the advances of modernity and interpreted them in such a way to conclude, for example, that individual will is the utmost virtue, or that the only virtue is the annihilation of virtue, have taken the valid findings of modernity and misunderstood their implications. These conclusions do not flow inexorably from modern epistemology or it's findings. Granted, such misinterpretations are fairly widespread, but this fact does not undermine the validity of modern epistemology itself. It only goes to demonstrate that many modern peoples don't comprehend modernity or it's consequences.
Apart from the actual validity of postmodern epistemology, I also find the idea that there has been a massive epistemological shift in American culture, or in the "collective conscious", toward the postmodern to be a specious claim. People who tend to make this argument do so when looking at humanity from a broad perspective, as a collective, rather than as a sum of individuals. From the former perspective it's understandable how one could reach such a conclusion, as there are macro-scale changes in society that might suggest that this is the case (the explosion of the internet and all of it's epistemological consequences, for example). From the latter perspective, however, the claim seems to lack any support. While the culture itself might be experiencing a particular shift that does not necessarily mean that the individuals within that culture are shifting in the same direction. Or, if they are, not necessarily in direct proportion to the massive cultural shifts (that is; there may have been a minor, not major, shift). Culture is not merely an equitably weighted sum of all the perspectives contained therein, and even if it were that, our society and culture would remain decidedly modern. If postmodernism was as pervasive a cultural influence as some claim, people would live their lives very differently than they actually do live them.
To conclude I want to reiterate the disclaimer at the opening of this piece: my defense of modern epistemology is not a defense of modernity in total. There are many aspects of modernity worthy of decrying, epistemology just isn't one of those things.