Trenton Merricks's "Propositions"

Trenton Merricks is Professor of Philosophy at the University of Virginia. He is the author of Objects and Persons, Truth and Ontology, and many articles in metaphysics, epistemology, philosophy of mind, philosophy of language, and philosophy of religion.

He applied the “Page 99 Test” to his new book, Propositions, and reported the following:

Page 99:

possible worlds. So, given Lewis’s account of possible worlds, I deny that there are sets of possible worlds. Propositions are sets of possible worlds only if there are sets of possible worlds. Thus my first reason for saying that, given Lewis’s account of possible worlds, propositions are not sets of possible worlds.

Given Lewis’s account of possible worlds, each possible world exists in—that is, is located in or is a part of—only one possible world, itself. So, given Lewis’s account of possible worlds, there is no possible world in which all the members of a set of possible worlds exist. So, given Lewis’s account of possible worlds, there is no possible world in which a set of possible worlds exists. So, given Lewis’s account of possible worlds, sets of possible worlds do not possibly exist. (The exceptions that prove the rule: sets of possible worlds with exactly one member.) Again, given Lewis’s account of possible worlds, sets of possible worlds are impossible entities.

Lewis believes that there are sets of possible worlds. But I do not think he would dispute my argument for the conclusion that, given his account of possible worlds, sets of possible worlds are impossible entities. For here is what Lewis says about ‘trans-world individuals’, which he takes to be single individuals that have parts located in various possible worlds:

It is possible for something to exist iff it is possible for the whole of it to exist. That is, iff there is a world at which the whole of it exists. That is, iff there is a world such that, quantifying only over parts of that world, the whole of it exists. That is, iff the whole of it is among the parts of some world. That is, iff it is part of some world— and hence not a trans-world individual; trans-world individuals are therefore impossible individuals. (1986a, 211)

Lewis believes that trans-world individuals exist. But he thinks that they are impossible.

Given Lewis’s account of possible worlds, sets of possible worlds are impossible entities. Lewis believes that there are some impossible entities. I do not. Indeed, the claim that some

The book Propositions has two main goals. The first is to show that there are propositions. The second is to defend an account of their nature. Questions about the existence and nature of propositions have been central to analytic philosophy throughout its history. And considerations from the philosophy of language have dominated the search for answers to those questions. You can see why. For propositions are supposed to be the fundamental bearers of truth and falsity. And propositions are supposed to be expressed by sentences that have truth-values. All of this fits squarely in the domain of the philosophy of language.

But to make claims about the existence and nature of propositions—entities whose existence and nature are matters of controversy—is not to engage in only the philosophy of language. It is also to engage in metaphysics. This book differs from most other discussions of propositions by its sustained focus on the metaphysical issues surrounding claims made about propositions. Here is just one example. Many linguists and philosophers of language say that propositions are “sets of possible worlds,” and often say this without a serious exploration of the metaphysics of possible worlds. But this book argues that the best account of the metaphysics of possible worlds rules out the thesis that propositions are sets of possible worlds. This book also argues that that thesis cannot be combined, without incurring new and serious problems, with any standard account of the metaphysics of possible worlds. Page 99 contains a snippet of this book’s argument for the conclusion that we should not combine the claim that propositions are sets of possible worlds with David Lewis’s famous (notorious) view that possible worlds are universes.

Learn more about Propositions at the Oxford University Press website.

--Marshal Zeringue