1. Division of labor - Specialization of tasks leads to increasing productivity and economic growth through virtuous circles.
2. Opportunity cost - The cost of any decision is the next best alternative forgone. This underpins concepts like scarcity, production possibility frontier, and discounting of investment returns.
3. Equimarginal principle - Resources are allocated efficiently when marginal benefits and costs are equal at the margin. This relates to market efficiency and externalities.
4. Market equilibrium - The interaction of supply and demand determines price and quantity in perfectly competitive markets. Elasticity, entry, and substitution principles also apply.