Keywords: Belief revision,
Conservatism, Informational economy, Minimal change, Minimum
mutilation, Theory change, Truth, Two Dogmas, Alchourron,
Gardenfors, Makinson, Quine.
Abstract: The paper attacks the widely held view that
belief revision theories, as they have been studied in the
past two decades, are founded on the Principle of
Informational Economy. The principle comes in two versions.
According to the first, an agent should, when accepting a
new piece of information, aim at a minimal change of his
previously held beliefs. If there are different ways to
effect the belief change, then the agent should, according
to the second version, give up those beliefs that are least
entrenched. Although widely proclaimed by belief revision
theorists, I argue that both versions of the principle are
dogmas that are not (and perhaps should not be) adhered to.
I substantiate this claim with two simple mathematical
observations, and I defend it against four possible
objections that involve contractions, reconstructions,
dispositions, and truths.