Review of Michael Dummett's "Thought and Reality" more

Thought and Reality. Michael Dummett. Paul Boghossian Thought and Reality is a lightly edited version of the Gifford Lectures that Michael Dummett gave at the University of St Andrews during the academic year 1996-97. In them he revisits some of the major themes that have preoccupied him over the course of his immensely distinguished career: meaning, truth, reality and the relation between them. The lectures culminate in a surprising argument for the existence of God, thus fulfilling the Gifford Lecturer’s charge “to promote and diffuse the study of Natural Theology…in other words, the knowledge of God.” Although the lectures are dense with argument, they are engaging and, for this notoriously difficult thinker, provide a relatively clear introduction to his philosophical system. Two master thoughts have dominated Dummett’s writings over the years. The first is that the metaphysical dispute between a realist and an anti-realist about a given domain – mathematics, for example, or the past – can only be usefully understood as a dispute about the proper account of the meaning of statements concerning that domain. The second is that, although each realist/anti-realist dispute must be settled on its own terms, there is a general argument, drawn from within the theory of meaning, which tends to favor anti-realist conceptions of meaning over their realist alternatives. According to a conjecture proposed by the Prussian mathematician Christian Goldbach in 1742, every even integer greater than 2 is the sum of two primes. Goldbach’s conjecture seems to be verified by particular cases (4=2+2; 6=3+3; 8=5+3;…); but to this day it has not been proven in full generality. The realist about mathematics thinks of the numbers as mind-independent, languageindependent abstract objects. Consequently, he thinks that Goldbach’s conjecture is either determinately true or determinately false, even if we may never discover which. The anti-realist, by contrast, thinks that numbers are, in one way or another, constructs of the human mind. Consequently, he does not think of it as guaranteed that Goldbach’s conjecture is either determinately true or determinately false. It all depends on whether we have built enough into our notion of number to settle the matter. Dummett’s first master thought is that this issue about the mind-independent existence of numbers can only be solved, if it can be solved at all, by settling whether our mathematical statements are true or false independently of our ability to show that they are — that is, by settling whether have “justification-independent truth conditions.” In effect, Dummett is recommending that we drop asking whether the numbers are mindindependent objects and put in its place the question: When someone thinks that every even number greater than 2 is the sum of two primes, is he thinking something that can be true or false even if we have no justification for accepting one or the other answer; or is he thinking something that can be true only if we have a certain sort of justification (for 1 example, a proof) for accepting it? Dummett’s second master thought is that considerations drawn from the theory of meaning support the claim that our statements, no matter what they are about, never have justification-independent truth conditions. Rather, according to the correct theory of meaning, the meanings of our statements are always given by their justification conditions, the conditions under which we would be justified in accepting them. Since, in the particular case of mathematics, justification is given by proofs, to say that Goldbach’s conjecture is true is to say that there is a proof of it; and to say that it’s false is to say that there is a proof that it cannot be proven. Since Goldbach’s conjecture may not be decidable (there may be neither a proof nor a disproof of it), it may not be determinately true or false. It is easier to sympathize with Dummett’s first master thought than with his second. The view that our only access to the metaphysical facts is through reflection on the meanings of our statements may not be obviously true; it may not even be prima facie plausible. But given the difficulty of explaining in what else our access to those facts might consist, it’s at least in the running. By contrast, Dummett’s “justificationist” view, that the meanings of our statements are given by the conditions under which we would be able to justify them, as opposed to the conditions under which they would be true, seems to lead to too many bizarre results to be acceptable. This is perhaps best brought out by its application to thoughts about the past. If we say that a statement about the past is true if and only if there is, at the time at which the statement was made, conclusive evidence for its truth, we would have to conclude that the past was constantly changing, since traces of past events may disappear completely as we move forward in time. To put it in maximally paradoxical terms: justificationism about the past leads to the view that past events, evidence for which has been lost, are expunged not merely from our knowledge but from reality itself. Dummett recognizes the implausibility of this outcome and has sought in later lectures (given later, but published earlier – see his Truth and the Past, Columbia University Press, 2004), to amend his account so as to avoid it. According to this later account, any statement (including one about the past) is true if and only if anyone suitably placed in time and space would be, or have been, in a position to establish it as true. This new proposal faces difficulties all its own, however, which cannot be discussed here. Dummett’s anti-realism leads him inexorably to the view that there could not have been a world without sentient beings. As he puts it, there would be no difference between God’s creating a universe in the whole of which there never was any creature able to experience it and His creating nothing at all. Of course, according to our best theories of the universe, its early stages contained no sentient beings; but, as Dummett rightly notes, that is not the same as saying that it never contained any. Still, Dummett’s conclusion here seems implausible: don’t we understand the difference 2 between God’s having created one hundred billion galaxies each with one hundred billion stars, none of them containing any sentient beings, and His having done nothing at all? Suppose we follow Dummett and agree that we cannot conceive of the world in complete independence of the manner in which we come to know it. We are, however, aware that there are other sentient creatures (dogs, for example, or orangutans) who apprehend it differently, creatures whose sensory experience and conceptual repertoire are very different from ours. How, then, are we to make sense of the idea that we all live in one common world? The realist, who believes in the world as it is in itself, independent of our ways of apprehending it, would easily be able to make sense of this seemingly compulsory thought. But how is the justificationist to do so? Dummett’s answer is God. We need to make sense of the world as it is in itself. But we sentient beings can only conceive of the world as it is from one or another conceptual perspective. Hence to make sense of the world as it is in itself we need to think of the world as apprehended by some mind that apprehends it, but not in any particular way. And that, according to Dummett, is the way God apprehends the world. So, making sense of this common world requires belief in God. And the realist who thinks he can conceive of the world independently of any way of apprehending it stands accused of endowing himself with powers that only God can have. Dummett’s unusual argument here assumes that it is easier to explain how we might have a conception of a being that apprehends reality as it is in itself, than it would be to explain how we might have a conception of such a reality ourselves. But it is not clear why the former conception would be any easier to have than the latter. Many of Dummett’s central conclusions may be implausible; but they are not capricious. Once the underlying justificationist conception of meaning is accepted, there is a certain inevitability to the progression of views that Dummett describes. Before we are made to swallow such indigestible claims, then, we should assure ourselves that the argument for a justificationist view of meaning is considerably stronger than the implausibility of the claims to which it seems to lead. Over the years, Dummett has used a variety of arguments to support his justificationist view of meaning, arguments that are rehearsed in the Gifford Lectures. He clearly thinks of these arguments as so powerful that they ought to sweep away the resistance with which justificationism’s consequences are likely to be greeted. I think it would be fair to say, however, that most philosophers have not shared his assessment of their strength. Dummett is certainly right that the truth conditional theorist owes us an account of what it is to grasp a thought with justification-independent truth conditions. But it is not at all clear, for reasons that emerge from reflection on Ludwig Wittgenstein’s considerations about what it is for someone to follow a rule, that the justificationist is in any better position to supply the corresponding account that would be demanded of him. No one has yet been able to say, in terms that are fully satisfying, what it is for someone to grasp a proposition with a particular content; just as no one has yet been able to say, in terms 3 that are fully satisfying, what it is for someone to undergo a conscious experience. Thought and Reality is a demanding but good introduction to the thought of one of philosophy’s most searching minds. That it may not be the last word on the difficult issues it treats was perhaps to be expected. 4