Mikroökonomie: Gleichgewicht und Wohlfahrt

Streit rankt sich nach wie vor um die Frage, ob Märkte ohne menschliche Eingriffe zum Optimum gelangen können, ob eine Marktwirtschaft überhaupt der Planwirtschaft überlegen ist, wenn ja, wie viele Eingriffe ein Markt verträgt, ehe er ineffizient wird usw. Die Positionen werden von Hayek und Keynes, von Ordo-Liberalismus und Planwirtschaft abgesteckt. Ein Problem damit, dass dieser Streit trotz der ungleichen Bilanz, die Kapitalismus als Form freier Marktwirtschaft und Sozialismus als Planwirtschaft vorzuweisen haben, liegt darin, dass vielen die Grundlagen nicht vertraut sind und sie vielen, denen sie vertraut sind, zu abstrakt sind, als dass sie damit etwas anfangen könnten. Eine Crash-Tour zu diesem Thema bietet Robert H. Franks im Zusammenhang mit seiner Erörterung von Gleichgewicht und Wohlfahrt.

“One of the simplest possible general equilibrium models is a pure exchange economy with only two consumers and two goods. For any given initial allocation of the two goods between the two consumers in this model, a competitive exchange process will always exhaust all possible mutually beneficial gains from trade. This result is known as the invisible hand theorem and is also called the first theorem of welfare economies.

If consumers have convex indifference curves, any efficient allocation can be sustained as a competitive equilibrium. This result is known as the second theorem of welfare economics. Its significance is that it demonstrates that the issues of efficiency and distributional equity are logically distinct. Society can redistribute initial endowments according to accepted norms of distributive justice, and then rely on markets to assure that endowments are used efficiently.

An economy is efficient in production if the marginal rate of technical substitution is the same for all producers. In the input market, too, competitive trading exploits all mutually beneficial gains from exchange.

Even though international trade leaves domestic production possibilities unchanged, its immediate effect is to increase the value of goods available for domestic consumption. With a suitable redistribution of initial endowments, a free trade economy will always be Pareto superior to a non-free trade economy.

Taxes often interfere with efficient resource allocation, usually because they cause consumers and producers to respond to different price ratios. The practical significance of this result is to guide us in the search for taxes that minimize distortions. The best tax, from an efficiency standpoint, is one levied on an activity that would otherwise be pursued too intensively.

Monopoly, externalities, and public goods are three other factors that interfere with the efficient allocation of resources.” (578)