As per Glen Whitman
Here’s the story of the Two Things. About three years ago, I was chatting with a stranger in a bar. When I told him I was an economist, he said, “Ah. So… what are the Two Things about economics?”
“Huh?” I cleverly replied.
“You know, the Two Things. For every subject, there are really only two things you really need to know. Everything else is the application of those two things, or just not important.”
“Oh,” I said. “Okay, here are the Two Things about economics.
One: Incentives matter.
Two: There’s no such thing as a free lunch.”
While simplistic, it’s amazing how often these two concepts form the underpinning of economic arguments. For instance, just read the posts on this blog.