# Necessitism vs contingentism

###### Peter Fritz (Australian Catholic University)

Peter Fritz

This course will discuss some recent work in philosophy on quantified modal logics. The course will be structured around a dispute between two philosophical views: necessitism and contingentism. Necessitism is the view that it is a necessary matter what there is. Contingentism is the negation of necessitism, i.e., the view that it is a contingent matter what there is. Many philosophers endorse contingentism. For example, consider the fact that your parents might not have met. In that case, you would not have been born, and so according to these philosophers, there would not have been you; thus, you are an example of something which is only contingently something. In a recent book («Modal Logic as Metaphysics», OUP 2013), Timothy Williamson argues for necessitism. According to him, had your parents not met, you would still have been something, although neither concrete nor a human: you would have been a merely possible human.

The first lecture introduces standard developments in first-order quantified modal logic, using two kinds of possible worlds models: first, models in which the domain of first-order quantifiers is independent of possible worlds, and second, models in which the domain of first-order quantifiers is relativized to possible worlds. The first fit the necessitist picture, and the second fit the contingentist picture. Each of the three remaining lectures begins with an argument for necessitism, and considers contingentist responses, each of which requires new logical developments. These include modal logics of propositional quantifiers, higher-order quantified modal logics, and questions concerning the expressive power of higher-order quantified modal logics.

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