  The birth and decline of disciplines are critical to science and society.
However, no quantitative model to date allows us to validate competing theories
of whether the emergence of scientific disciplines drives or follows the
formation of social communities of scholars. Here we propose an agent-based
model based on a \emph{social dynamics of science,} in which the evolution of
disciplines is guided mainly by the social interactions among scientists. We
find that such a social theory can account for a number of stylized facts about
the relationships between disciplines, authors, and publications. These results
provide strong quantitative support for the key role of social interactions in
shaping the dynamics of science. A "science of science" must gauge the role of
exogenous events, such as scientific discoveries and technological advances,
against this purely social baseline.
