UPDATE: I further clarify some of the points made here at a different post.
Leiter has a post on an open letter by Bob Pasnau listing reasons why one might choose to specialize in the history of philosophy. I haven’t read all the comments ensuing from Leiter’s post carefully enough, but it is clear that the issue is not only whether specializing in the history of philosophy is a good career move, but more generally whether the history of philosophy is important at all for philosophical inquiry.
Full disclosure: as somebody whose list of publications is composed mostly of historical papers, I am of course not in any way neutral on this matter (and neither is Pasnau, for similar reasons). Even when I am not doing history of philosophy properly speaking, my philosophical analyses tend to be historically-informed: I like to know where the issues I discuss come from, and what other people before me have said on the matter, before I venture voicing my own views. I think there are thousands of arguments on why a philosopher who knows her history of philosophy will almost always be a better philosopher than one who does not, even when doing systematic work, and Pasnau has presented some of them. In a nutshell, the point can be summarized by two famous quotes on the relation between philosophy and its history:
“Philosophy, without its history, is blind, and the history of philosophy, without an understanding of philosophy, is empty.” (a paraphrase of Kant's famous slogan relating concepts and intuitions; not sure what the source is for this exact formulation)
"Philosophy without the history of philosophy, if not empty or blind, is at least dumb." (Sellars)
Here I want to discuss a crucial role I think the history of philosophy can have for contemporary philosophical theorizing, even when one is not engaging in historical analysis properly speaking. It is related to my suspicions towards intuition-based philosophical methodology, also articulated here. One of the issues I have with reliance on intuitions for philosophical theorizing is that intuitions are often presented as obvious, basic facts over which there can be no rational debate. (I always have to think of that old Beatles song: “You say yes / I say no / You say why / And I say I don’t know”.) In other words, it is unclear how divergences in philosophical intuitions could be resolved and arbitrated, as the general perception seems to be that with intuitions you hit rock bottom; no further debate is possible (I suspect that this conception of intuitions is to be traced back to Moore, but I haven’t done my homework here yet).
But once you start thinking about it more carefully, it becomes evident that (most) philosophical intuitions do come from somewhere, they are not these ‘obviously true’ freestanding facts that we are lucky enough to have insight into. My general claim is that most, if not all, relevant philosophical intuitions are a product of the historical development of philosophy as a discipline. Many views which were once proposed as substantive and non-trivial then slowly but surely established themselves as truisms, as facts that nobody in their right mind would want to question. And yet, they were at some point substantive, and typically depend on a lot of assumptions, many of which we may not be prepared to endorse. So we endorse these ‘winners’ in the evolutionary competition between philosophical memes as obviously true and unproblematic, and these become our loved and cherished philosophical intuitions (a big chunk of them, in any case).
Hence, one of the very significant uses that historical analysis can have for current theorizing is to show us where our philosophical intuitions come from, and in particular on which assumptions they seem to rest. It is a mistake to think that discrepancies between intuitions cannot be discussed, as it is a mistake to take intuitions as the über-authority when it comes to philosophical analysis; intuitions can and should be scrutinized, and looking into the history of their establishment is a great way to engage in such an enterprise.
I call the enterprise of understanding where our intuitions and philosophical dogmas come from ‘conceptual archeology’, and have done quite a bit of it myself, in particular with respect to the concept of formality and logic. In here, I have argued that the very idea that it makes sense to think of logic from the point of view of the form vs. matter distinction, which is currently the ‘obvious’ way to think about logic, rests on substantive and even contentious assumptions. In his dissertation, MacFarlane had already convincingly argued that the slogan ‘Logic is formal’ is a Kantian substantive thesis, which rests crucially on Kant’s transcendental idealism and thus on a lot of views most of us are not prepared to endorse these days. And yet, we all take for granted the slogan that logic is formal. In my work, I have tried to continue the good work started by MacFarlane by going back to Aristotle, the Ancient Commentators and the Latin medieval authors in order to identify precisely the main steps in the developments towards our current ‘textbook’ views about logic. The upshot is to argue that the ‘intuition’ that logic is formal, i.e. that formality (in its many senses) should be viewed as a criterion for logicality, is not to be taken for granted: it is precisely what needs to be discussed.
More generally, I would love to see more work of ‘conceptual archeology’ being done, so that we can get a better picture of the sources for many of our ‘obviously true’ philosophical intuitions. And clearly, this can only be done in a thoroughly historically-informed way. In a slogan, the history of philosophy can serve as an antidote to over-reliance on philosophical intuitions, and that’s much needed medicine if you ask me. This being said, I think the history of philosophy is at its most exciting when it can contribute to systematic discussions (a view that encounters quite a lot of resistance among ‘hardcore’ historians). But even purely historical work is much needed in the background if we are to do conceptual archeology at all, so rather than a dichotomy, to my mind it’s all part of the same big and exciting enterprise which is philosophy.