question - just question, not challenge - for the contextual historians

Justin, Catarina, and by implication Eric have all talked about the line between history and history of philosophy recently on this blog.  So I have a question that seemed worth a separate thread.

First, I take it no one thinks there is a lack of intrinsic value in the history of anything.  It's a perfectly fine thing to think about any historical question you like.  And let's grant that it is silly to suppose that the only connection of historical study to contemporary philosophy is that it immediately answers the same questions someone is asking now.  It might give us a critical stance on those questions, show us where they come from, provide new concepts, challenge our intuitions, demonstrate the contingency of our social-conceptual constructs, etc.  But anything like that is what you Catarina was calling "instrumental". The philosophical value - the philosophical nature of the project - is in its relation to contemporary philosophy. 

I take we all also think there is some history of philosophical figures or their views, that really isn't philosophy at all, that is straight history.  (The parts of the Monk biographies that weren't bad, for example, if that isn't too mean.)  That isn't to say that there is a precise line, that it isn't contextual, etc., but sometimes a historical project moves from being philosophical to being not philosophical. 

Note that this is nothing unique to history.  As Catarina says, there are all manner of fields - I would claim all - that should usefully inform philosophy.  I look at math a lot, and this same thing happens all the time.  Someone like Dana Scott is doing high-level math, but it is philosophical in a clear way.  And at some point, he stopped being engaged in philosophy - at least in much of his work - and turned to math and computer science. Still proving theorems, but without any concern at all for the illumination they might bring to philosophy. That isn't to say that there might not be some philosophical pay-off from this work - as there might be for absolutely anything - but it is to say that he is not, in this work, a philosopher.  (Much to his credit, Dana does this work in math and computer science departments and publishes in those journals.) 

Now one reason this matters is that it is a legitimate question how much should be done in a philosophy department and how much in another one.  (I mean this not in the sense that some have expressed here of "I'm going to pack up and leave for history because philosophy is so inhospitable, but in the sense of "I'm not really doing philosophy, and so shouldn't take up a philosophy position from someone who is.") An analogous case that I believe comes up a lot is the relation of math to econ.  There are some economists who pay next to no attention to empirical data and claim to be game theorists, or some such.  But then what they do in game theory is really basic - proving things that would be homework assignments in a good grad program in math.  None of this would even count toward tenure in math, but they hide in econ as if they are doing something else.  If one thinks that example uncharitable to all economists, pretend it is hypothetical. You can imagine such a person.  And I am not at all claiming that any particular historian of philosophy does this, but we can imagine such a person, I assume. If one is doing math, physics, history, art criticism, etc. with no real engagement with contemporary philosophy, it seems that philosophers are not competent to judge the work and that one should subject that work to the people who are.

I take it a part of the view of Justin, Eric, and maybe Catarina, is that the current vague line between what should be done in a philosophy department and what shouldn't is drawn wrongly.  The thought seems to be that the line should include much more historical work on the philosophy side than it does now.  (Though of course there is no unanimous view about what the right line is in the profession.)  That seems like a perfectly plausible view to me.  But what I'd like to know is how the historians on this blog think we should draw the line.   Is the measure still in terms of some notion of engagement with contemporary philosophy?  Or is there some other consideration that would suggest that there should be a field of history of philosophy, housed in philosophy rather than history, where engagement with contemporary philosophizing is in no way an essential desideratum. 

I imagine that some of you have published on this, but I'd love it if you could give me the comic-book version of the answer here.