Geolibertarianism, a libertarian form of Henry George's philosophy called geoism, is considered left-libertarian because it assumes land to be initially owned in common, so that when land is privately appropriated the proprietor pays rent to the community. Geolibertarians generally advocate distributing the land rent to the community via a land value tax as proposed by Henry George and others before him. For this reason, they are often called "single taxers". Fred E. Foldvary coined the term geo-libertarianism in a "Land and Liberty" article. In the case of geoanarchism, the voluntary form of geolibertarianism as described by Foldvary, rent would be collected by private associations with the opportunity to secede from the rent-sharing community and not receive the community's services.