Left-libertarianism, also known as egalitarian libertarianism, left-wing libertarianism or social libertarianism, is a political philosophy and type of libertarianism that stresses both individual freedom and social equality. Left-libertarianism represents several related yet distinct approaches to political and social theory. In its classical usage, it refers to anti-authoritarian varieties of left-wing politics such as anarchism, especially social anarchism, whose adherents simply call it "libertarianism". In the United States, it represents the left-wing of the libertarian movement and the political positions associated with academic philosophers Hillel Steiner, Philippe Van Parijs and Peter Vallentyne that combine self-ownership with an egalitarian approach to natural resources. This is done to distinguish libertarian views on the nature of property and capital, usually along left–right or socialist–capitalist lines.