This inquiry began with a deceptively simple question. How does it happen that serious people continue to believe in progress, in the face of massive evidence that might have been expected to refute the idea of progress once and for all? The attempt to explain this anomaly—the persistence of a belief in progress in a century full of calamities—led me back to the eighteenth century, when the founders of modern liberalism began to argue that human wants, being insatiable, required an indefinite expansion of the productive forces necessary to satisfy them. Insatiable desire, formerly condemned as a source of frustration, unhappiness, and spiritual instability, came to be seen as a powerful stimulus to economic development. Instead of disparaging the tendency to want more than we need, liberals like Adam Smith argued that needs varied from one society to another, that civilized men and women needed more than savages to make them comfortable, and that a continual redefinition of their standards of comfort and convenience led to improvements in production and

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