DB: You're not big on theories. Why not?
NC: I think theories are great. I work on them all the time. But the term "theory" shouldn't be abused. You have a theory when you have some non-obvious principles from which you can draw conclusions that explain in surprising ways some of the phenomenon that are worth studying. That's hard to do. It's done in the hard sciences. There are a few other areas where it's done. But for the most part it's impossible. You can understand that. Even in the sciences, when you get to matters of any complexity, theoretical understanding declines quite sharply.
When you get to human affairs, I can't even think of anything that deserves the name, "theory." Marx is certainly worth studying. He was a theorist of capitalism. He developed a certain abstract model of capitalism. There's nothing wrong with abstract idealizations. That's the way to study things. He investigated what might happen in that kind of system. How much relationship it had to the real world of that time or this time, one has to ask. He had essentially nothing to say about socialism, a few scattered sentences here and there. He had no theory of revolution or social change. But you study what he did for its important work, and one should know about it. If you want to call it a theory, OK.
A lot of what people call theoris in social sciences - literary theory and others - is obfuscation. I don't know of any understanding that goes deep enough so that you can't present it very simply and in such a way that the principles are pretty much on the surface. We're living in an era when a lot of prestige is given to professional expertise. People have a real responsibility not to claim more than they can offer. If you claim to have a theory that deduces unexpected consequences from nontrivial principles, lets see it....