 According to Abstractionists, possible worlds are abstract objects of some sort. The exercise in probability calculation from  section 1.2  motivates an Abstractionist proposal in which states of affairs are the basic building blocks. States of affairs are possible outcomes. Kripke called possible outcomes “miniature possible worlds”. This suggests an idea of what a possible world is: it is a maximal state of affairs. Pollock (1984a: 57) defines possible world therefore as follows: