Bi-Modal Naive Set Theory

  • John Wigglesworth Munich Center for Mathematical Philosophy, LMU Munich


This paper describes a modal conception of sets, according to which sets are 'potential' with respect to their members.  A modal theory is developed, which invokes a naive comprehension axiom schema, modified by adding `forward looking' and `backward looking' modal operators.  We show that this `bi-modal' naive set theory can prove modalized interpretations of several ZFC axioms, including the axiom of infinity.  We also show that the theory is consistent by providing an S5 Kripke model.  The paper concludes with some discussion of the nature of the modalities involved, drawing comparisons with noneism, the view that there are some non-existent objects.

How to Cite
WIGGLESWORTH, John. Bi-Modal Naive Set Theory. The Australasian Journal of Logic, [S.l.], v. 15, n. 2, p. 139-150, july 2018. ISSN 1448-5052. Available at: <>. Date accessed: 12 dec. 2018. doi: