Kwame Anthony Appiah taught the introduction to philosophy class I took the fall of my freshman year, and it was sufficiently impressive that I signed on to major in it. I followed that up with a seminar he taught, and he remains one of the most brilliant and learned people I’ve ever encountered. So his work is always recommended here, and The Honor Code: How Moral Revolutions Happen is no exception. This is a book not about how people win ethical arguments, but about how people cause ethical practice to change. He observes that it was generally acknowledged that all the good arguments were on the side of anti-dueling in England quite a bit before dueling died out and asks how it that a practice can persist under those circumstances and what brings it to an end.
His answer, which has to do with honor, entails sort of throwing caution (and social scientific validity to the wind) but is monstrously interesting and the exact reverse of all the stereotypes of academic overspecialization and who-cares-ism.
Excerpt here, NPR segment here. This is not a work of “real” philosophy, but if you want an introduction to the disciplined as practiced in the contemporary United States Appiah’s Thinking It Through is your best bet and he also does work of the “this is boring and weird” variety.