Wood also argues that Locke also provides a justification for the dispossession of indigenous land. The idea that making land productive serves as the basis of property rights establishes the corollary that the failure to improve land could mean forfeiting property rights. Under Locke's theory, "[e]ven if land is occupied by indigenous peoples, and even if they make use of the land themselves, their land is still open to legitimate colonial expropriation." Locke's notion that property "derives from the creation of value, from 'improvement' that enhances exchange value, implies not only that mere occupancy is not enough to establish property rights, or even that hunting-gathering cannot establish the right of property while agriculture can, but also that insufficiently productive and profitable agriculture, by the standards of English agrarian capitalism, effectively constitutes waste." Economist John Quiggin argues that this fits into a larger fundamental criticism of Locke's labor theory of property which values a particular type of labor and land use (i.e. agriculture) over all others. It thus does not recognize usage of land, for example, by hunter-gatherer societies as granting rights to ownership. In essence, the Lockean proviso depends on "the existence of a frontier, beyond which lies boundless usable land. This in turn requires the erasure (mentally and usually in brutal reality) of the people already living beyond the frontier and drawing their sustenance from the land in question." Locke's theories of property rights are often interpreted in the context of his support for chattel slavery of "prisoners captured in war" as a philosophical justification for the enslavement of Black Africans and expulsion or killing of Native Americans by early American colonists to gain their land. See also Entitlement theory First possession theory of property Georgism Homestead principle Propertarianism References Theories of law Property John Locke