Very brief summary
Rorty's overall thesis can be stated in rough terms as follows. The western philosophical tradition, at least from Plato onwards, has focused on trying to identify the Truth about how things Really are. This is a hopeless endeavour, because in order to succeed it would require us somehow to get directly in touch with real Reality in a way that was not mediated by our historically contingent social practices, the most important of which is language. Rorty agrees with Nietzsche, that our understanding of the world is perspectival all the way down. And this means that all explanations and “truths” are provisional; there can be no stopping point, because it is always possible for somebody to use their imagination to come up with new explanations and “truths” that are “better” (more on “better” below) than their predecessors.
Rorty argues that it is high time for a paradigm shift in philosophy. We should give up on arguing about how things really are, and instead should, humbly accepting our ultimate finitude, get on with searching for new, more powerful, accounts of the world we live in and of our lives in it. The only aim of endeavouring to increase our knowledge and understanding, he argues, should be to increase our ability to do things in the world and to live richer and fuller human lives. Because humans are inescapably caught in webs of language and culture that are utterly contingent in origin, they can never reach the perspective-free standpoint that would be required to access the really Real. Only God could do that.
Competing explanations and “truths”, says Rorty should be compared purely on how much they help us do new things and live richer lives. And this is why he describes himself as a pragmatist in the tradition of Dewey, James etc. All explanations should be judged against pragmatic criteria, which amounts to asking how useful they are. None of this should change the content of things that count as knowledge and small t truths (eg scientific knowledge). It just offers (to Rorty) a more honest account of what we mean when we claim something is “true”. Ultimately, “hard facts” are things that people sharing a social practice all agree upon, things which if denied might lead to ascriptions of insanity or deviance.