This dissertation explores the megamachine, a prominent metaphor in American humanist and philosopher of technology, Lewis Mumford's Myth of the Machine series. The term refers critically to dynamic, regimented human capacities that drive scientific and technical innovation in society. Mumford's view of the nature of collectives focuses on qualities and patterns that emerge from the behavior of groups, societies, systems, and ecologies. It is my aim to reenergize key concepts about collective capacities drawn from Lewis Mumford's critique of historical and modern sociotechnical arrangements. I investigate the possibility of accessing those capacities through improved design for Technology Assessment (TA), formal practices that engage experts and lay citizens in the evaluation of complex scientific and technical issues.

I analyze the components of Mumford's megamachine and align key concerns in two pivotal works that characterize the impact of collective capacities on society: Bruno Latour's Pasteurization of France (1988) and Elias Canetti's Crowds and Power (1962). As I create a model of collective capacities in the sociotechnical according to the parameters of Mumford's megamachine, I rehabilitate two established ideas about the behavior of crowds and about the undue influence of technological systems on human behavior. I depart from Mumford's tactics and those of Canetti and Latour and propose a novel focus for STS on "sociotechnical crowds" as a meaningful unit of social measure. I make clear that Mumford's critique of the sociotechnical status quo still informs the conditions for innovation today.

Using mixed mode qualitative methods in two types of empirical field studies, I then investigate how a focus on the characteristics and components of collective human capacities in sociotechnical systems can affect the design and performance of TA. I propose a new model of TA, Emergent Technology Assessment (ETA), which includes greater public participation and recognizes the interrelationship among experience, affect and the material in mediating the innovation process. The resulting model -- the "soft" megamachine --introduces new strategies to build capacity for responsible innovation in society.