This book presents a theory of technological evolution based on recent scholarship in the history of technology and relevant material drawn from economic history and anthropology. The organization and content of its chapters are determined by the nature of the evolutionary analogy and not by the need to provide a chronological account of events in the history of technology. However, because this study is primarily historical, not an exercise in the philosophy or sociology of technology, historical examples are used throughout to elucidate and support the theoretical framework. Major developments in the history of technology, such as the invention of the steam engine or the advent of the electrical lighting system, are introduced simultaneously with the unfolding of an evolutionary explanation of technological change.

The opening chapter announces three themes that reappear, with variations, in later sections of the work: diversity — an acknowledgment of the vast number of different kinds of artifacts, or made things, that have long been available; necessity — the belief that humans are driven to invent artifacts to meet basic biological needs; and technological evolution — an organic analogy that explains both the appearance and the selection of these novel artifacts. A close examination of these themes reveals that diversity is a fact of material culture, necessity is a popular but erroneous explanation of diversity, and technological evolution is a way of accounting for diversity without recourse to the idea of biological necessity.