and its omonymous journal. Despite their differences, anarchist schools of thought are forms of libertarian socialism. Anarchists may see those categorisation in materialist terms. From a materialist perspective, individualist anarchism represents the anarchist form in the pre-capitalist and largely agrarian merchantilist capitalism before the Industrial Revolution, during which individualist anarchism became a form of artisanal and self-employed socialism, especially in the United States. Social anarchism represents the anarchism in an industrial society, being the form of industrial or proletarian socialism, with post-left anarchy and its criticism of industrial technology and anti-workerism arising in a post-industrial society. Before socialism became associated in the 20th century with Marxist–Leninist states and similar forms of authoritarian and statist socialism, considered by some as state capitalism and administrative command economies rather than planned economies, socialism was a broad concept which was aimed at solving the labor problem through radical changes in the capitalist economy. This caused issues between anarchists and anarcho-capitalists, whose understanding of socialism is that of the 20th century Marxist–Leninist states, with capitalism meaning the free market rather than actually existing capitalism. Left and right anarchism Left anarchism and left-wing anarchism distinguish social anarchism from anarcho-capitalism and anti-state right-libertarian philosophies. Left anarchism represents political philosophies which posit a future society in which private property is replaced by reciprocity and non-hierarchical society. Left anarchism is sometimes used synonymously with libertarian socialism, left-libertarianism, or social anarchism. Anarchists typically discourage the concept of left anarchism on grounds of redundancy and that it lends legitimacy to the notion that anarchism is compatible with capitalism or nationalism. German author Ulrike Heider categorizes anarchism into left anarchism (anarcho-syndicalism), right anarchism (anarcho-capitalism) and green anarchism. Free-market anarchism Although laissez-faire has been commonly associated with capitalism and anarcho-capitalists advocate such a system, there is a similar left-wing or socialist laissez-faire system called free-market anarchism, also referred to as free-market anti-capitalism and free-market socialism to distinguish it from laissez-faire capitalism. One first example of this is mutualism as developed by Pierre-Joseph Proudhon in the 18th century, from which emerged individualist anarchism. Benjamin Tucker is one eminent American individualist anarchist who adopted a laissez-faire system he termed anarchistic socialism in contraposition to state socialism. This tradition has been recently associated with contemporary scholars such as Kevin Carson, Roderick T. Long, Charles W. Johnson, Brad Spangler, Sheldon Richman, Chris Matthew Sciabarra and Gary Chartier, who are critics of laissez-faire as commonly understood and instead