Joel shouldn’t talk of things he doesn’t understand.
When I was in college I took two intro economics courses: macroeconomics and microeconomics. Macro was full of theories like “low unemployment causes inflation” that never quite stood up to reality. But the micro stuff was both cool and useful. It was full of interesting concepts about the relationships between supply and demand that really did work. For example, if you have a competitor who lowers their prices, the demand for your product will go down unless you match them.
via Strategy Letter V – Joel on Software.