Usually, academia is inquiry: physicists are inquiring into how matter and energy work, historians are inquiring into what happened and why, etc. From a distance, postmodern philosophy looks like it is inquiring into how society works, what hidden assumptions we have, etc.
But it isn't, really. It's a game about who can say the most interesting thing, constrained by some rules about how things being said have to be grounded in other things that have been said, and with some way of scoring interestingness that i don't have a firm grip on. There's no genuine attempt to understand things, or to test what is said against reality. Truth doesn't matter at all. Foucault, for example, was successful not because he said true things, but because he said new and previously unimaginable things, and expressed them lyrically.