The source of modal truth
Abstract
This thesis concerns the source of modal truth. I aim to answer the question: what is
it in virtue of which there are truths concerning what must have been the case as a
matter of necessity, or could have been the case but isn't.
I begin by looking at a dilemma put forward by Simon Blackburn which attempts to
show that any realist answer to this question must fail, and I conclude that either horn
of his dilemma can be resisted. I then move on to clarify the nature of the
propositions whose truth I am aiming to find the source of.
I distinguish necessity de re from necessity de dicto, and argue for a counterpart
theoretic treatment of necessity de re. As a result, I argue that there is no special
problem concerning the source of de re modal facts. The problem is simply to
account for what it is in virtue of which there are qualitative ways the world could
have been, and qualitative ways it couldn't have been.
I look at two ways to answer this question: by appealing to truthmakers in the actual
world, or by appealing to non-actual ontology. I develop a theory of truthmakers, but
argue that it is unlikely that there are truthmakers for modal truths among the
ontology of the actual. I look at the main possibilist ontology, David Lewis' modal
realism, but argue that warrant for that ontology is unobtainable, and that we
shouldn't admit non-actual possibilia into our ontology.
I end by sketching a quasi-conventionalist approach to modality which denies that
there are modal facts, but nevertheless allows that we can speak truly when we use
modal language.
Type
Thesis, PhD Doctor of Philosophy
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