ABSTRACT
While the idea that simplicity has a role in guiding our ideas about nature is an old and recurrent theme in philosophy, there are a variety of competing notions of simplicity and no agreement on which should play a role in theory choice or why. This chapter argues that one type of simplicity plays a basic role in guiding the construction of models and has a special importance in fundamental ontology. I will introduce it, convey a sense of how it works, articulate the intuitive justification for its role, and show that it unifies a surprising array of theoretical practices and explanatory principles.
