Belief Dynamics. (Epistemo)logical Investigations
Allard Tamminga

Abstract:
This thesis deals with the dynamics of belief. In three
interconnected, though independent studies, a viable alternative to
foundational approaches in epistemology is explored. Rather than
accept the research agenda dictated by traditional epistemology, with
its stress on the pursuit of conditions under which our beliefs are
justified or even true, the present work follows the lead of American
pragmatism, and focusses on the articulation and defense of criteria
according to which a change of mind may be judged legitimate.

The second and third chapters discuss the attempts of two pragmatist
philosophers, Charles Sanders Peirce and Isaac Levi, to formulate and
to formalize the belief-doubt-belief model, a model that sets out to
set forth systematically the optimal strategies according to which to
change our minds.

In the course of this undertaking, more and more logical
considerations come to the fore, culminating in a discussion and an
evaluation of formal systems for belief change. It is argued that
belief change systems, despite the naturalistic setting in which they
were first conceived, have outgrown their pragmatist origin and have
metamorphosed into a branch of philosophical logic, where empirical
considerations have become obsolete. To restore the connection between
logical theory and epistemological practice, a case is made for
reformulations of belief change systems that are cleared from elements
that obstruct practical applications and empirical tests.

In the fourth chapter, a belief change system is presented that (1)
uses finite representations of epistemic states, (2) can deal with
inconsistencies adequately, (3) has finite operations of change, (4)
can do without, but does not rule out, extra-logical elements, and (5)
only licenses consistent beliefs. An Appendix, where the underlying
logic of the belief change system of the fourth chapter is studied
proof-theoretically, concludes the thesis.