In property-owning societies there will arise opportunities for exchange. Since property is itself a social institution, society will have a stake in ensuring that the terms of exchange are fair and that limits of exchange and property are set, so that some things, such as the labour of children, should not be traded at market prices. Extreme political and economic libertarianism or market fundamentalism denies that anything other than the free operation of markets themselves is needed to solve this and practically all other political problems. Extreme communism takes the diametrically opposing line that the social evils of exploitation and injustice can only be solved by eliminating private property itself. See also ideal market, Marxism.