An old joke among economists goes: "all you have to do to teach a parrot to be an economist is to teach him how to say supply and demand."
There's a lot of truth to that joke. I think it's the interpretation of the forces that move a market into equilibrium that makes economics rigorous. Economics is the study of how people behave under conditions of scarcity. The joke assumes that all there is to economics is the static equilibrium and not the marginal changes.