Purposive Action and Unintended Consequences

Intended and anticipated outcomes of purposive action are always, in the nature of the case, relatively desirable to the actor, though they may seem objectively negative to an outside observer. In any case, they pose few questions to social theory. In contrast, unintended consequences, being unplanned, unexpected results of action orientated towards some goal, become a phenomenon demanding a social-scientific explanation. In fact, this phenomenon has attracted the attention of outstanding political and social thinkers from Machiavelli and Vico to Marx, Pareto, Max Weber, and, more recently, Hayek, and Popper. As Robert Merton (1949) has pointed out, however, the diversity of context and variety of terms by which this phenomenon has been known in the past have tended to obscure its generality. In the eighteenth century Adam Smith and other Scottish thinkers such as David Hume, Adam Ferguson, and Dugald Stewart succeeded in building up a social theory that made unintended, or unforeseen, consequences of purposive human action its central object (Schneider 1967). The theory was used to analyse the existence and functioning of institutions, such as governments, and of social aggregates, such as states or social classes. Adam Smith's ‘invisible hand’, by which ‘man is led to promote an end which was no part of his intention’, is the best-known application of the Scottish approach.

The social-scientific relevance of unintended consequences of purposive action has been further demonstrated by such twentieth-century theorists as Friedrich Hayek and Karl Popper.