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312 Conversion

obviously to believe that the experiment was carried out incorrectly, not to
reject three centuries of physics. Likewise, should i abandon my belief that a
low fat diet is healthy because i read about a single study that did not find any
benefit of such a diet? A belief system is the cumulative product of a lifetime of
discussing, listening, observing, reading and thinking; it makes little sense to
throw it away in response to a single piece of contradictory information.
Dissonance reduction through peripheral change might appear irrational
when viewed from a logical perspective, but the latter is merely one perspec-
tive among others. it has no special claim on our attention. if we view the cog-
nitive system from a homeostatic perspective instead, then peripheral belief
revision appears similar to other processes that keep body and mind in bal-
ance by counteracting the impact of external disturbances. As we respond to
an increase in ambient temperature on a hot day by sweating, so we respond to
contradictory information by minimizing its impact on our worldview.

CONVERSION: SCIENCE AS EXAMPLE

if resistance through peripheral change were the whole truth about belief
formation, belief systems could become more detailed, extensive and inter-
connected, but core beliefs could not change. But people do revise their core
beliefs. in particular, the natural sciences have undergone multiple radical
conversions – called scientific revolutions or theory changes – in which funda-
mental hypotheses were replaced by other, qualitatively different hypotheses.
For example, scientists have converted from a flat to a round earth; from a
geocentered to a heliocentered planetary system; from believing that planets
necessarily move in circles to the belief that they move in elliptical orbits; from
the phlogiston theory to the oxygenation theory of combustion; from the belief
that earth, air, water and fire are the fundamental elements to the periodic table
of chemical elements; from the hypothesis that mountain formation is due to
the cooling and shrinking of the earth to the belief that mountains form when
one tectonic plate crashes into another; from the belief that objects move due
to their impetus to the principle that objects remain in rectilinear motion until
some force acts on them; from the belief that diseases are due to an imbalance
between the body’s “humors” (fluids) to the germ theory; and so on.
Philosophers and historians have mined this track record for suggestions
about conversion processes. They start from the same assumption as resis-
tance theorists in psychology: Theory change is triggered by contradictory
information. But whereas resistance theorists, dismayed by, for example, racial
prejudice, tend to emphasize the minimal, even irrational character of such