France, Spain, Cuba and Portugal. Murray Bookchin's first book Our Synthetic Environment was followed by his essay "Ecology and Revolutionary Thought" which introduced ecology as a concept in radical politics. In the 1970s, Barry Commoner, claimed that capitalist technologies were chiefly responsible for environmental degradation as opposed to population pressures. In the 1990s socialist/feminists Mary Mellor and Ariel Salleh adopt an eco-socialist paradigm. An "environmentalism of the poor" combining ecological awareness and social justice has also become prominent. Pepper critiqued the current approach of many within green politics, particularly deep ecologists. Syndicalism Syndicalism operates through industrial trade unions. It rejects state socialism and the use of establishment politics. Syndicalists reject state power in favour of strategies such as the general strike. Syndicalists advocate a socialist economy based on federated unions or syndicates of workers who own and manage the means of production. Some Marxist currents advocate syndicalism, such as De Leonism. Anarcho-syndicalism views syndicalism as a method for workers in capitalist society to gain control of an economy. The Spanish Revolution was largely orchestrated by the anarcho-syndicalist trade union CNT. The International Workers' Association is an international federation of anarcho-syndicalist labour unions and initiatives. Criticism According to analytical Marxist sociologist Erik Olin Wright, "The Right condemned socialism as violating individual rights to private property and unleashing monstrous forms of state oppression", while "the Left saw it as opening up new vistas of social equality, genuine freedom and the development of human potentials." Because of socialism's many varieties, most critiques have focused on a specific approach. Proponents of one approach typically criticise others. Socialism has been criticised in terms of its models of economic organization as well as its political and social implications. Other critiques are directed at the socialist movement, parties, or existing states. Some forms of criticism occupy theoretical grounds, such as in the economic calculation problem presented by proponents of the Austrian School as part of the socialist calculation debate, while others support their criticism by examining historical attempts to establish socialist societies. The economic calculation problem concerns the feasibility and methods of resource allocation for a planned socialist system. Central planning is also criticized by elements of the radical left. Libertarian socialist economist Robin Hahnel notes that even if central planning overcame its inherent inhibitions of incentives and innovation, it would nevertheless be unable to maximize economic democracy and self-management, which he believes are concepts that are