All the Power in the World Peter Unger Oxford University Press January 2006 ISBN 0-19-515561-0 Peter Unger has changed his views somewhat since he wrote three famous philosophical papers – "I do not exist", "Why there are no people" and "Why there are no ordinary things" – in 1979. He now thinks not only that there are people, that he does exist and that there are ordinary things, but also that any adequate philosophy – what he calls any "humanly realistic philosophy" – must begin by acknowledging these facts. Believers in ordinary things will be relieved. However, Unger now thinks that these ordinary truths are put under pressure by what he calls the "scientiphical metaphysic" which dominates contemporary philosophy. He labels this metaphysical view "scientiphicalism", because it is neither entirely scientific nor entirely philosophical, but some unholy blend of the two. The main burden of his long new book is to launch an attack on scientiphicalism. Scientiphicalism is the view that the world is entirely constituted by matter arranged in space, and that everything that happens is fixed by the exercise of the physical powers of purely physical things. Other philosophers these days might call scientiphicalism "physicalism" or "materialism". Unger's old college friend and one of the targets of this book, David Lewis, was undoubtedly a scientiphicalist, but called himself a materialist. Although Unger wants to distinguish scientiphicalism from physicalism, no harm will be done if I refer to the doctrine as "physicalism" in what follows. For most of the ideas essential to scientiphicalism are also shared with today's physicalism: in particular, its claim that "all the power in the world is physical power". This is one of the ideas that Unger wants to refute. One the two main themes of his book is a defence of the dualist view that mental substances or individuals are wholly non-physical, and have the power to make things happen in the physical world. For example, we have the power to act freely, and the evident exercise of this power is incompatible with physicalism, since physicalism says that every state of the universe is fixed by its previous physical state plus the (deterministic or indeterministic) laws of nature. So free choice can play no role in making things happen. This argument is familiar, of course, though Unger's own version of it is characteristically inventive. Less familiar are Unger's ingenious arguments for dualism later in the book, based on the "problem of the many" for which Unger is well known. Consider your cat, now sitting on the mat. It has, let us suppose, a definite number of hairs at any one time. Now consider the body of matter which is your cat, minus one of its hairs. This body of matter is (surely) also a cat, and it is also on the mat. But it is not identical with your cat, since identical cats must surely have the same number of hairs at any one time. But since your cat has thousands of hairs, how do we then avoid the conclusion that there are thousands of cats now sitting on the mat? The "problem of the many" was originally introduced with this example by P.T. Geach, and christened by Unger in famous article of that name in 1980. In All the Power in the World Unger applies this reasoning to the physicalist view that you and your mental life are entirely physical. If Unger himself, say, were a purely physical thing (say, for the sake of argument, his brain) then we can apply the reasoning above to establish the conclusion that there are many, many thinkers more or less where his brain is; whereas of course, there is really only one. In a fascinating discussion, in my view the best part of this book, Unger draws the conclusion that he is not a physical thing: dualism is true and physicalism is false. The second main theme of the book is that whatever the truth of dualism, physicalism is inadequate as an account of the physical world, and therefore fails even on its own terms. According to Unger, objects in the physical world have three basic kinds of property or attribute. There are spatial properties, like the shape and size of an object, and then there are the propensities of objects, like the electric charge of a particle (some call these dispositions or powers). But there are also what Unger calls the qualities of objects, which are reducible neither to spatial properties nor to propensities. The prime example of a quality – though not the only example – is the colour of an object. An object's colour is neither a merely spatial property like its size and nor is it a mere propensity: rather, it is something which fills space, and cannot be exhaustively characterized in terms of its powers. The contrast between qualities (in Unger's sense) on the one hand, and spatial properties plus propensities on the other, can be illustrated by discussion in Locke's 1689 Essay Concerning Human Understanding. Locke's metaphysical picture only allows objects to have spatial properties and powers. The question arose of what the hardness of a piece of matter is, since it does not seem to be a spatial property, like size or shape. Locke's response to this problem is to interpret hardness as impenetrability: the power to resist pressure from other objects. Likewise, colours are interpreted by Locke as powers to produce experiences in us. In Unger's terminology, for Locke, qualities are explained in terms of propensities. According to Unger, the characteristic thesis of today's physicalism is something it shares with Locke: its denial of the existence of qualities. Like Locke's theory of matter, it only recognizes spatial properties and powers. Unger argues against physicalism with a thought experiment. Imagine a world consisting of a number of solid spheres moving in empty space. Now imagine a world consisting of a matter-filled "plenum" with spherical "bubbles" of the same dimensions as the spheres in the first world, which "move" through the plenum just as the spheres do. Plainly there is a difference between these two worlds. But according to Unger, physicalism cannot account for this difference, since it thinks of physical reality purely in terms of geometrical properties and propensities, and in order to characterize the difference between these two worlds, you need qualities. Yet physicalism denies that there are any qualities. So physicalism cannot be true. The argument is interesting, though hardly conclusive as it stands, as Unger himself recognizes. Physicalists could challenge Unger's claim that they cannot describe any difference between the two worlds. For the spheres are, we might suppose, rigid, and rigidity is some kind of propensity to resist force. Spherical bubbles on the other hand are not rigid, so they do not have the same propensities. Unger will respond that rigidity can no more be exhaustively characterized in terms of a propensity to resist force than hardness can be characterized as impenetrability. But the physicalist could go further, and reject Unger's threefold classification of properties altogether, while keeping the essential heart of physicalist metaphysics. According to Lewis, for example, our world consists fundamentally of physical properties instantiated at spacetime points, and everything else is determined by this "mosaic" of physical properties. Lewis thinks that there are dispositions, but only in the sense that there are true dispositional descriptions of properties. For example, calling a sugar cube soluble (a dispositional description) is just to describe some of its micro-structural physical properties. In this sense, then, dispositions are reducible to fundamental physical properties which also have non-dispositional characterizations. Towards the end of his life, Lewis spent a lot of time worrying about the nature of these fundamental properties, but his worries did not lead him in the direction of Unger's qualities, something for which he saw no need. Unger disagrees with Lewis's conception of dispositions. But it is worth pointing out that some defenders of physicalism would agree with Unger here that some physical properties (e.g. charge) are dispositional in their fundamental nature. This suggests that the pertinent disagreement here is over the nature of dispositions or propensities and not over the truth of physicalism or "scientiphicalism" as such. What about qualities? Does a physicalist have to deny their existence? Certainly physicalists like Lewis and D. M. Armstrong do not see things this way. Just as Locke reduced qualities like solidity to propensities, so some of these physicalists reduce them to spatial properties. D. M. Armstrong and Frank Jackson, for example, have argued that colours should be identified with the "primary" qualities of objects: geometrical properties of surfaces which are the basis of the dispositions coloured objects have to reflect light in various ways, and which enables us therefore to see them. Physicalism can give a reduction of Unger's qualities just as it can give a reduction of dispositions. There are physicalist theories of colour. Unger considers some versions of physicalist "identity theories" of qualities, but his objections to an identity theory of qualities and propensities are very much tied to these particular versions. Jackson's "primary quality view of colour", for example, is not considered by Unger, and is untouched by his criticisms. In general, it seems to me that Unger's defence of qualities has less to be said for it than his argument for dualism – the arguments are less forceful and the discussion would have been better if he had considered a wider range of contemporary discussions of dispositions (of which there are many). By his own declaration, Unger is determined not to consider many contemporary views, but his discussion is weaker for it. Unger has always been a very original and independent philosopher, never swayed excessively by fashion. He is also very proud of his own independence. Time after time in this book we are told how unfashionable the doctrines he is propounding are, and how they are not taken seriously by the "scientiphical" orthodoxy. As one might expect from someone who once wrote a paper called "I do not exist", Unger revels in his declared eccentricity, which he thinks of as a consequence of the fearless pursuit of the truth, following the wind of argument wherever it leads, regardless of fashion. What is fashionable, of course, depends on when and where you live. Scientiphicalism might be all the rage in New York these days, I don't know; but other parts of the philosophical world would not necessarily recognize it as the orthodoxy. For example, there has been a revival of interest in dualism, partly because of David Chalmers's work, and many of the most influential philosophers today (including Saul Kripke, Tyler Burge, Hilary Putnam, John McDowell, Timothy Williamson, Peter van Inwagen and Unger's colleague Kit Fine) are very far from being scientiphicalists. Like many self-appointed eccentrics, Unger sometimes overrates his own eccentricity. All the Power in the World is a vast, rambling, and (despite its charm) very extravagant book. The acknowledgements alone run to eight pages. For a book of this size, it is quite readable, if you are not put off by Unger's chatty, in-your-face style (which I am not). Unger rants and harangues on one page, just as he seduces and coaxes the reader on the next. This has always been his way, and it has its appeal, though it gets a bit tiring in such a long book. But the book would have been better if it had been shorter. Unger's earlier papers are classics partly because of their originality, and partly because they give concise expression to deep and difficult philosophical problems (the vagueness of our ordinary thinking, the problematic nature of ordinary material objects, the contextsensitivity of many predications etc.) in an appealing style. All the Power in the World is certainly appealing, but it is not so concise. Some of its main ideas have been published in shorter papers already. Fortunately, Oxford University Press has recently reprinted Unger's papers in two useful volumes. Those with time on their hands will find much of interest in All the Power in the World. Others would perhaps be better advised to consult the collected papers. Tim Crane is Professor of Philosophy at UCL, and Director of the University of London's Institute of Philosophy. He is the author of Elements of Mind (Oxford 2001).