Knowledge is indivisible. When people grow wise in one direction, they are sure to make it easier for themselves to grow wise in other directions as well. On the other hand, when they split up knowledge, concentrate on their own field, and scorn and ignore other fields, they grow less wise — even in their own field.
The problem of déformation professionnelle is real but mostly American. It would be suicide in the American academy to show too early an interest beyond your doctoral specialization: charges of everything from charlatanry to ambition would be levied and tenure denied. I’ve seen this first-hand. This is because the American graduate school universe was created by Germans (refugees) and echoes many of the worst as well as the best features of its model: deep academic research, carefully limited range of materials, engagement in internally-referential debates and utter unconcern for the market. These are not all bad qualities—without them we would not have had some of the world’s greatest historical monographs. But they inhibit people for decades from putting their nose above a parapet. I have always loved sticking my nose about a parapet, so long as I had a decent weapon to hand. That’s partly an English trait, partly an Oxbridge trait and probably mostly a recessive Judt trait. John Dunn, my favorite King’s supervisor, once described me as “the silver-tongued orator”: a barbed compliment, since it suggested that I spoke before I thought and seduced rather than convinced, but I like it all the same.