Scepticism and the content of “commonsense”

We think, and we speak our thoughts. Necessarily we speak them, even to ourselves, in some language, either in a so-called natural one – French, English, Hebrew, Greek – or in one of the so-called artificial languages of mathematics or formal logic. Whatever language we choose to speak, or must speak, however, we take ourselves often enough, most often perhaps, to be speaking in it of real things: things “real” in the sense, a sense introduced to philosophy by Descartes, and the source of much enduring intellectual anguish since, of being “outside the mind.”

But are not words themselves creatures of language? Is language itself not a creation of the human mind? If so, what assurance have we that, when we speak, we speak of the furniture of the universe, of Reality itself, rather than merely of the homely, and home-made, furniture of our own minds?

In raising such doubts we envisage the possibility that language, although it may seem the house of the mind, with windows opening on an extramental, extralinguistic world, may in fact be a prison, with none. The image of language as a prison no doubt owes something, historically, to Plato's myth of the Cave. But those immured in the Prison-House of Language, as philosophers since Locke have conceived it, are rather worse off than those chained facing the back wall of Plato's Cave.

This book is the product of a transatlantic cross-fertilisation. The authors found themselves from 1991 onwards members of the same department, at the University of Utah, to which Harrison had moved from a British university (Sussex). At that time, Hanna was nourishing some doubts about various forms of meaning-scepticism, mainly in Quine and Kripke. Harrison had a number of projects on hand, one of which was an absurdly ambitious attempt to rethink the philosophy of language since Frege from the standpoint of an idiosyncratic reinterpretation of Wittgenstein. Some of the component parts of this enterprise, including a series of exegetical studies of middle-period Wittgenstein, had seen or were about to see print, but the project as a whole was, to put it bluntly, stalled, and had been stalled, except on its exegetical front, since the early 1980s. Conversation between us at first revealed some points of contact between our two projects. Then we began to see the possibility of certain large structural moves that would get Harrison's project moving again, in directions that would provide a framework for Hanna's ideas. At first we thought the work might yield a joint paper. Later we realised that it would have to be a series of papers. Finally we resigned ourselves to producing a joint book. By this time so many changes had occurred in each of our minds, stemming from objections or suggestions by the other, that we would have been at a loss to say which of us “owned” which parts of the project.

Sense and truth-conditions

It has been a commonplace of philosophy since Frege that “the sense of a sentence is determined by its truth-conditions.” But that, as it stands, is a dark utterance. We need for a start to distinguish between the sentence and its sense. A sentence is just a string of words. Different sentential strings may have the same sense: “express,” as is often said, “the same proposition.” Both (some) sentences and the propositions they express may be said to be assertoric in form, in the sense that what each expresses is the content of an assertion. It is this that makes “The cat is on the mat” an altogether different sort of logical entity from a mere string of names: “James Peter John.” So one could say that both sentences and propositions aim at truth. What one means by that, roughly speaking, is that only in the case of the kinds of sentence that express the content of a possible assertion does the question of truth arise. As Frege put it, “The only thing that raises the question of truth at all is the sense of sentences.” But to raise the question of truth and falsity is not necessarily to be susceptible of truth or falsity. Even an assertoric sentence, such as “The cat is on the mat,” cannot be said to be in its own right true or false.