Fish argues that the trouble with Principle is that it is an empty concept—that we fill talk of principle with whatever commitments we already bring to the table. In a way, he’s simply stating what Alvin Plantinga says in Warrented Christian Belief re: presuppositions, bases, etc. Fish is a coherentist, but his broader point is that the form your Epistemological or other philosophical commitments take is immaterial; we will always act on the basis of unchallenged assumptions that may or may not have much relation to the form we pick when we start talking about them. He makes an exception for religion—indeed, he seems to disbelieve in the possibility of a religion that is not exclusive and demanding, one that does not reject big-L Liberalism (because to accept Liberalism is to accept ideas of tolerance and fairness as more basic than religious beliefs). In the end, though, the main thrust of the book is political—the language of theory is being usurped by the Right, and we need to get it back if we really believe that certain things are good, etc. That’s fine, because according to Fish everything is political/rhetorical. I should note that Fish wrote this book over a decade ago, and much of the political landscape has changed—though how much would be hard for me to say. Eight years of Bush and the growing power of the Religious Right, the fight over gay marriage, etc. certainly have a bearing on Fish’s argument, but I’m not equipped right now to trace exactly what that bearing might be.