a social formation where capitalist class processes dominate, but are not exclusive. To these thinkers, capitalist class processes are simply those in which surplus labor takes the form of surplus value, usable as capital while other tendencies for utilization of labor nonetheless exist simultaneously in existing societies where capitalist processes are predominant. However, other late Marxian thinkers argue that a social formation as a whole may be classed as capitalist if capitalism is the mode by which a surplus is extracted even if this surplus is not produced by capitalist activity as when an absolute majority of the population is engaged in non-capitalist economic activity. David Harvey extends Marxian thinking through which he theorizes the differential production of place, space and political activism under capitalism. He uses Marx’s theory of crisis to aid his argument that capitalism must have its "fixes", but that we cannot predetermine what fixes will be implemented, nor in what form they will be. This idea of fix is suggestive and could mean fix as in stabilize, heal or solve, or as in a junky needing a fix—the idea of preventing feeling worse in order to feel better. In Limits to Capital (1982), Harvey outlines an overdetermined, spatially restless capitalism coupled with the spatiality of crisis formation and its resolution. Furthermore, his work has been central for understanding the contractions of capital accumulation and international movements of capitalist modes of production and money flows. In his essay, "Notes towards a theory of uneven geographical development", Harvey examines the causes of the extreme volatility in contemporary political economic fortunes across and between spaces of the world economy. He bases this uneven development on four conditionalities: (1) the material embedding of capital accumulation processes in the web of socio-ecological life; (2) accumulation by dispossession; (3) the law-like character of capital accumulation in space and time; and (4) political, social and "class" struggles at a variety of geographical scales. Weberian political sociology In some social sciences, the understanding of the defining characteristics of capitalism has been strongly influenced by 19th century German social theorist Max Weber. Weber considered market exchange rather than production as the defining feature of capitalism. In contrast to their counterparts in prior modes of economic activity, capitalist enterprises are characterized by their rationalization of production, directed toward maximizing efficiency and productivity, a tendency leading to a sociological process of enveloping rationalization. According to Weber, workers