Stephen Schiffer

There are two things we must know in order to know what vagueness is. We must know what kinds of things can be vague. Evidently, predicate and sentence types can be vague, but what about tokens of those types? What about statements and other speech acts? What about abstract entities such as properties and propositions? And what about names and the boundaries of physical objects? Then, of course, for each kind of thing that can be vague, we must know in what vagueness for that kind consists. Needless to say, that there are these two questions doesn’t mean that we should try to answer the first before trying to answer the second.

Suppose we think in a language of thought. Then Paul Boghossian' is prepared to argue, first, that there may be ambiguous Mentalese expression types that have unambiguous tokens, and, second, that the way in which this is possible allows for otherwise valid theoretical or practical reasoning to be rendered invalid owing to equivocation of a sort that may be undetectable to the reasoner. Paul sees this as a possible basis from which to launch an argument for what some might call "narrow content", and this is a question I'll take up later

In The Things We Mean I argue that there exist such things as the things we mean and believe, and that they are what I call pleonastic propositions. The first two chapters offer an initial motivation and articulation of the theory of pleonastic propositions, and of pleonastic entities generally. The remaining six chapters bring that theory to bear on issues in the theory of content: the existence and nature of meanings; knowledge of meaning; the meaning relation and compositional semantics; the relation between content-involving facts and underlying physical facts; vagueness and indeterminacy; conditionals; normative discourse; and the role of propositional content in explanation, prediction, and knowledge acquisition.

I’m going to argue for something that some of you will find repugnant but which I can’t help thinking may be true—namely, that there are no determinate moral truths. As will become apparent, my interest in moral discourse as manifested in this paper derives more than a little from my interest in the theory of meaning. Moral discourse has always presented a puzzle for the theory of meaning and philosophical logic, and I take myself to be following the advice of Bertrand Russell when he recommended testing philosophical theories by their capacity to deal with puzzles, “since these serve much the same purpose as is served by experiments in physical science.” Section (1) offers an epistemological argument for the claim that there are no determinate moral truths. This argument raises further questions, which subsequent sections try to answer. In the course of answering those further questions, another, non-epistemological, argument is offered for the claim that there are no determinate moral truths. In the end, I hope we see not only that there are no determinately true moral propositions, but what it is about moral concepts which makes that so

SI is a paradox because it presents four appearances that cannot all be veridical: first, it appears to be valid—after all, it’s both classically and intuitionistically valid; second, its sorites premiss, (2), seems merely to state the obvious fact that in the sorites march from 2¢ to 5,000,000,000¢ there is no precise point that marks the cutoff between not being rich and being rich; third, premiss (1), which asserts that a person with only 2¢ isn’t rich, is surely true; and fourth, the conclusion (3), which asserts that a person with 5,000,000,000¢—i.e. $50 million—isn’t rich, is surely false.