“Collapse is a broad term that can cover many kinds of processes. It means different things to different people. Some see collapse as a thing that could happen only to societies organized at the most complex level. To them, the notion of tribal societies or village horticulturalists collapsing will seem odd. Others view collapse in terms of economic disintegration, of which the predicted end of industrial society is the ultimate expression.

A society has collapsed when it displays a rapid, significant loss of an established level of sociopolitical complexity. The term ‘established level’ is important. To qualify as an instance of collapse a society must have been at, or developing toward, a level of complexity for more than one or two generations.

The collapse, in turn, must be rapid – taking no more than a few decades – and must entail a substantial loss of sociopolitical structure. Losses that are less severe, or take longer to occur, are to be considered cases of weakness and decline. Collapse is manifest in such things as: a lower degree of stratification and social differentiation; less economic and occupational specialization, of individuals, groups, and terri­tories; less centralized control; that is, less regulation and integration of diverse econo­mic and political groups by elites; less behavioral control and regimentation; less investment in the epiphenomena of complexity, those elements that define the concept of ‘civilization’: monumental architecture, artistic and literary achievements, and the like; less flow of information between individuals, between political and economic groups, and between a center and its periphery; less sharing, trading, and redistribution of resources; less overall coordination and organization of individuals and groups; a smaller territory integrated within a single political unit.

Collapse is a general process that is not restricted to any type of society or level of complexity. Complexity in human societies is not an all-or-nothing proposition. Societies vary in complexity along a continuous scale, and any society that increases or decreases in complexity does so along the progression of this scale. There is no point on such a scale at which complexity can be said to emerge. Hunting bands and tribal cultivators experience changes in complex­ity, either increases or decreases, just as surely as do large nations. Collapse, involving as it does a sudden, major loss of an established level of complexity, must be considered relative to the size of the society in which it occurs. Simple societies can lose an established level of complexity just as do great empires. Sedentary horticultur­alists may become mobile foragers, and lose the sociopolitical trappings of village life. A region organized under central chiefly administration may lose this hierarchical umbrella and revert to independent, feuding villages. A group of foragers may be so distressed by environmental deterioration that sharing and societal organization are’ largely abandoned. These are cases of collapse, no less so than the end of Rome, and no less significant for their respective populations. To the extent, moreover, that the collapses of simpler societies can be understood by general principles, they are no less illuminating than the fall of nations and empires. Any explanation of collapse that purports to have general potential should help us to understand the full spectrum of its manifestations, from the simplest to the most complex. This, indeed, is one of the central points and goals of the work. These points made, it should be cautioned that in fact defining collapse is no easy matter. The present discussion may serve to introduce the orientation, but the definition will have to be added to as the work progresses.”

Joseph Tainter in The Collapse of Complex Societies (1988)