If you get a well labelled dataset, I think this is pretty thoroughly within the scope of current machine learning technologies, but that means spending perhaps hundreds of hours labelling papers as a certain amount postmodern out of 100. If you're trying to single out the postmodernism that you're convinced is total BS, then that's more complex. Doable but you need to make the case to me about why it would be worthwhile, and what exactly your aim would be.