Scientific Reasoning and Belief Structure

For explaining theory change, it is important to be able to express which theory is believed to be fundamental and which theory is thought to be true. To achieve this expressive power, I propose theory of belief structures (TBS) that describes belief states not in terms of a set of sentences but by a structure. The dominant formal approach of belief revision, the AGM theory, adopts a conservative strategy. However, this does not always conform to the praxes of scientists. Contrarily, TBS admits to taking a progressive strategy and can describe different kinds of belief states. To demonstrate the descriptive power of TBS, it is applied to a description of change in astronomical theory.