In Paradigms and Barriers Howard Margolis offers an
innovative interpretation of Thomas S. Kuhn's landmark idea
of "paradigm shifts," applying insights from cognitive
psychology to the history and philosophy of science.
Building upon the arguments in his acclaimed Patterns,
Thinking, and Cognition, Margolis suggests that the
breaking down of particular habits of mind—of critical
"barriers"—is key to understanding the processes through
which one model or concept is supplanted by another.

Margolis focuses on those revolutionary paradigm shifts—
such as the switch from a Ptolemaic to a Copernican
worldview—where challenges to entrenched habits of mind
are marked by incomprehension or indifference to a new
paradigm. Margolis argues that the critical problem for a
revolutionary shift in thinking lies in the robustness of the
habits of mind that reject the new ideas, relative to the
habits of mind that accept the new ideas.

Margolis applies his theory to famous cases in the history of
science, offering detailed explanations for the transition
from Ptolemaic to cosmological astronomy, the emergence of
probability, the overthrow of phlogiston, and the emergence
of the central role of experiment in the seventeenth century.
He in turn uses these historical examples to address larger
issues, especially the nature of belief formation and
contemporary debates about the nature of science and the
evolution of scientific ideas.

Howard Margolis is a professor in the Harris Graduate School
of Public Policy Studies and in the College at the University
of Chicago. He is the author of Selfishness, Altruism,
and Rationality and Patterns, Thinking, and
Cognition, both published by the University of Chicago
Press.