rights should be rejected. Some critics reject the distinction between positive and negative rights, including Peter Marshall and Noam Chomsky. Marshall argues that the anarcho-capitalist definition of freedom is entirely negative and that it cannot guarantee the positive freedom of individual autonomy and independence. About anarcho-capitalism, Chomsky has written: Anarchists argue that certain capitalist transactions are not voluntary and that maintaining the class structure of a capitalist society requires coercion which violates both anarchist principles and anarcho-capitalism's non-aggression principle. Anarchists view any ownership claims on land and natural resources as immoral and illegitimate. While anarchists, including individualist anarchists, market anarchists and mutualists, adamantly oppose absentee ownership, anarcho-capitalists have strong abandonment criteria in which one maintains ownership until one agrees to trade or gift it. Anarchists critics of this view tend to have comparatively weak abandonment criteria as one loses ownership when one stops personally occupying and using it. Furthermore, the idea of perpetually binding original appropriation is considered to be anathema to anarchist schools of thought as well as to any moral or economic philosophy that takes equal natural rights to land and the Earth's resources as a premise. Definitional issues Anarchist schools of thought encompass not only a range of individual schools, but also a considerable divergence in the use of some key terms. Some terms such as socialism have been subject to multiple definitions and ideological struggle throughout the period of the development of anarchism. Others such as capitalism are used in divergent and often contradictory ways by different schools within the tradition. In addition, the meanings of terms such as mutualism have changed over time, sometimes without spawning new schools. All of these terminological difficulties contribute to misunderstandings within and about anarchism. A central concern is whether anarchism is defined in opposition to hierarchy, authority and the state, or simply capitalism and the state. Debates over the meaning of anarchism emerge from the fact that it refers to both an abstract philosophical position and to intellectual, political and institutional traditions, all of which have been fraught with conflict. Some minimal, abstract definitions encourage the inclusion of figures, movements and philosophical positions which have historically positioned themselves outside, or even in opposition to, individuals and traditions that have identified themselves as anarchist. While anti-statism is central, there is a lot of talk among scholars and anarchists on the matter and various currents perceive anarchism slightly differently. While it