Fiction poses a set of problems relating to the notion of fictional truth and the reading of a fictional text, which link in with questions regarding counterfactuals and belief change. They are thus problems which modern logic, in this instance nonmonotonic logic, would like, or should like, to deal with. However, logics have, so far, not had much to offer. This paper argues that this is because logicians are not treating the correct problem. They assume in their logics an exogenous factor (similarity between worlds, epistemic entrenchment, selection function, to take but a few examples), whereas what is required is an understanding of this factor and the value it takes. This question essentially involves the dynamics: understanding this factor amounts to giving an account of how it comes to have a particular value in a particular context or at a particular moment. The paper contains a consideration of what should count as the essential tasks of such a theory of dynamics, and a tentative suggestion as to one direction for developing such a theory.
