Epistemology is the attempt (or the study of attempts) to establish the grounds, or framework--'foundation'--for knowledge/truth that is necessarily intersubjectively valid, is it not? The more I learn, the more I am convinced that the postmodernists among us (of which I am not one) have got at least this much right: every human being has the capacity to decide for oneself what one accepts as truth/knowledge, no matter what.

For 'true' postmodernists that is to be celebrated as the ultimate 'emancipation'. I am horrified. Yet, regarding most of life it is of no consequence.

Material existence, however, produces material consequences. To refuse to accept the realities of material existence is to invite material disaster. Refusing to accept the reality of global warming (and environmental degradation generally) and refusing to accept vaccinations against infectious diseases when those are available are examples.

Another example is refusing to accept an ethic of justice that is shown to follow from observation within material existence (that can itself be universally verified by human beings). Whether justice is present or absent is rife with material consequences--and not only in the economy.