How and why do we define the long eighteenth?

A reader emailed me a few days ago wondering how we define the boundaries of our field and whether those boundaries are influenced by our feelings about the periods that lie on the borders. (In particular, he noticed that at least Tedra, David and I have expressed a little hostility toward Romanticism as one of the reasons for our interest in the eighteenth.) Finally, he wonders how important we find the study of philosophy to our various disciplines. How explicitly do we find ourselves teaching philosophical ideas (or even texts) to students?

As I tried to write a response, I realized that my own answers to these questions are terribly idiosyncratic and that the same is probably true for each of us. I will open these good questions up for discussion.