 The most important argument for markets that builds on consequences, however, concerns their ability to deliver efficient outcomes and to create high levels of welfare. They spur economic growth, while not relying on a central planning mechanism, but on the self-interest of individuals. This is what the famous Smithian metaphor of the “invisible hand” (WN IV.II.9) is usually taken to stand for. Under certain assumptions, such as stable preferences, the absence of external effects on third parties, equal and open access to information, and the absence of one-sided bargaining power, market outcomes are Pareto efficient. This has been shown in the first theorem of welfare economics (for the formal proof see e.g., Mas-Colell/Whinston/Green 1995, ch. 16). Pareto efficiency means that no individual’s position in terms of satisfaction of her preferences can be improved without reducing another individual’s position, i.e. there is no waste caused by unused possibilities of bargaining. The strict mathematical conditions of the first theorem of welfare economics never hold in practice. But the general equilibrium model embodies two arguments about markets that explain why they can spur economic growth, and these can also be applied to real markets. The first can be called the “coordination argument” (cf. Roemer 2012): the price system can transmit complex information about people’s preferences in decentralized ways, which allows for the allocation of goods and services to where they are most wanted. The emerging spontaneous order satisfies social needs in better ways than could be achieved by central planning (see notably von Hayek 1945). Market prices serve as an instrument for determining the opportunity costs of certain uses of resources, which also allows for comparisons of the different sets of resources individuals hold (see Dworkin 2000, ch. 1 and 2). 