Introduction

In this chapter I want to discuss the way in which physical science has come to claim a particular kind of hegemony over other subjects in the second half of this century. This claim to hegemony is generally known by the name of physicalism. In this chapter I shall try to understand why this doctrine has come to prominence in recent decades. By placing this doctrine in a historical context, we will be better able to appreciate its strengths and weaknesses.

As a preliminary, note that contemporary physicalism is an ontological rather than a methodological doctrine. It claims that everything is physically constituted, not that everything should be studied by the methods used in physical science. This emphasis on ontology rather than methodology marks a striking contrast with the ‘unity of science’ doctrines prevalent among logical positivists in the first half of the century. The logical positivists were much exercised by the question of whether the different branches of science, from physics to psychology, should all use the same method of controlled observation and systematic generalization. They paid little or no attention to the question of whether everything is made of the same physical stuff.

By contrast, physicalism, as it is understood today, has no direct methodological implications. Some physicalists uphold the view that all sciences should use the “positivist” methods of observation and generalization.

In the first post World War II identity theories (e.g., Place [1956], Smart [1962]), mind-brain identities were held to be contingent. However, in work beginning in the late 1960s, Saul Kripke ([1971], [1980]) convinced the philosophical community that true identity statements involving names and natural kind terms are necessarily true and, furthermore, that many such necessary identities can only be known a posteriori. Kripke also offered an explanation of the a posteriori nature of ordinary theoretical identities such as that water = H2O. We identify the kinds and substances involved in theoretical identities by certain of their contingent properties. What we discover when we discover a theoretical identity is the underlying nature of the kind that we identify by those contingent properties.

Now, of course, it was being a posteriori, not being contingent, that mattered to the identity theorists anyway, so the necessity of identity is not, in itself, damaging to mind-brain identity theories. However, Kripke also argued persuasively that the alleged mind-brain identities could not be treated in the same way as ordinary theoretical identities. We “identify” pain by feeling it, and surely how it feels is an essential property of pain, not a contingent property. Thus, a mind-body identity theory must provide a different explanation of why its identities are a posteriori.

A new wave of materialists has appeared on the scene with a new strategy for explaining the a posteriori nature of its alleged identities. The strategy is to locate the explanation for the a posteriori nature of mind-body identities, not on the side of the world, but on the side of the mind – in different ways of thinking about or imagining, or in different concepts.

Introduction

There has been considerable worry for the last thirty years about the causal efficacy of the mental: How, given the closure of physics and the apparent “irreducibility” of the mental to the physical, can mental phenomena play any causal/explanatory role in the world? Aren't they mere “epiphenomena”? In reaction to these worries, Tyler Burge (1993) has reasonably argued that:

And Lynn Rudder Baker (1993) has rightly suggested that we:

Baker and Burge are applying the sensible point, suggested years ago by Moore and emphasized by Quine (1953a), that there seems to be no specially privileged position outside of common sense and science from which philosophers can effectively dismiss them. It would take a pretty powerful metaphysical argument indeed to give us reason to give up our belief in familiar forms of mental causation.

For all the wisdom of this position, however, I fear that Burge overstates the case in a crucial way. The problem of “epiphenomenalism” that many of these “metaphysical” discussions have been addressing arises in part from the difficulty of specifying a mechanism linking the mental and the physical.

The problem of mental causation is at the heart of the mind-body problem. And for physicalist or materialist views of mind, the key to solving the problem of mental causation is getting a satisfactory understanding of how the mental is realized in the physical. Recent discussions of physicalism have focused on the notion of supervenience; but I think that the focus should instead be on the notion of realization. Supervenience comes in a variety of forms – and the form we need to understand, in order to understand mental causation, is that in which the properties in the supervenience base can be said to realize the properties that supervene on them. Any physicalist theory, whether or not it is a functionalist theory, needs to maintain that the mental is realized in the physical, and so needs an account of realization. But my main focus will be on the realization of functional properties.

I take as my point of departure a recent paper by George Bealer that attempts to show that functionalist accounts of mind cannot give a satisfactory account of self-consciousness. Although Bealer's primary target is functionalism, he takes his arguments to establish a version of property dualism. They are supposed to show that mental properties are “first-order properties,” not the higher-order properties functionalists take them to be. And because Bealer thinks that there are decisive reasons for rejecting type physicalism, he thinks that the only way for mental properties to be first order is for them to be nonphysical.

I shall argue in this chapter that the discussion of nonreductive materialism has been conducted under the shadow of an ambiguity in the sense of reductive. One sense is specific to the philosophy of mind, and here the reductive tradition is marked by the attempt to give an account of the mind in behavioral or functional terms, without remainder. The other sense derives from the philosophy of science, and it concerns the possibility of giving some kind of systematic account of “higher” sciences in terms of “lower” ones, and, ultimately, in terms of physics. I shall argue that failure to distinguish these senses in Davidson's “Mental Events” has led to serious confusions in the discussion of “nonreductive materialism” and in the attendant notion of ‘supervenience.’ Davidson has clarified the confusion in “Mental Causes”, but in a way that makes his original contribution much less interesting than it had seemed to be. In the course of the discussion, I hope to clarify the various senses in which theories, properties, and predicates can be ‘reduced’ or ‘emergent.’

Story 1. In order to vindicate a materialist theory of the mind it is necessary to show how something that is a purely physical object can satisfy psychological predicates. Those features of the mind which seem to be, prima facie, incompatible with this physicalism – such as consciousness and the intentionality of thought – must, therefore, be explained in a way that purges them of their apparently Cartesian elements, which would be incompatible with materialism.

The word physicalism, when introduced into philosophical conversation by Neurath and Carnap, seemed theirs to define, much as a century earlier the word positivism had been Comte's to define. Not everyone is so lucky as to introduce a label by which they will later become known, and such was the lot of Locke who has been tossed with Hobbes and Hume into the catchall bin of Empiricism. Whether original with Locke or presaged in Leviathan, the idea that Ideas were all the mind could contemplate seems distinctive enough to deserve its own ‘ism.’ In any event, the marriage of Locke's internal Empiricism with Comte's cold Positivism produced the uneasy union that the Vienna Circle styled ‘physicalism,’ but that the world has since come to call by turns ‘Logical Positivism’ and ‘Logical Empiricism.’ That a philosophical position could be defined by conjoining two seemingly mismatched themes would itself be of at least historical interest. But it gains a more topical interest if we could show how antiphysicalist theses more recently bandied about were born of the same unhappy union. To that end we will begin in the middle.

Consistent with their antimetaphysical approach to philosophy, Neurath and Carnap cast their original definition of physicalism in linguistic terms. Roughly, physicalism was the name they gave to the thesis that every meaningful sentence, whether true or false, could be translated into physical language. Although both thought the thesis obviously true, neither thought it knowable a priori.

It is a commonplace that much of contemporary metaphysics is deeply bound up with the metaphysical modalities: metaphysical possibility and necessity. To take one central instance, the mind-body problem, in its most familiar contemporary form, appears as a problem about property identities, and it is hard to imagine discussing any issue about property identity without calling on the idea of metaphysical possibility. If we want to ask whether the property of being conscious, or being in pain, or having this sort of pain S, is identical with some physical or functional property P – say, the property of having such-and-such neurons firing in such-and-such a way – we typically begin by asking whether I could have had these neurons firing in this particular way, without experiencing S. And the could here is the could of metaphysical possibility.

As we all know, these questions about what could be the case – metaphysically could – are far from easy to answer. There are, it seems to me, two features of the notion of metaphysical possibility that combine to make them hard to settle, either negatively or positively. What makes them hard to settle negatively is that because metaphysical possibility is supposed to be a kind of possibility distinct from physical possibility, styles of argument that work very well to show that various describable situations are not physically possible do not carry over to show that the same situations are not metaphysically possible. Most of us would agree that the standard correlations between brain and pain already give us excellent reasons for believing that it is not physically possible for there to be a perfect neurological duplicate of me who feels no pain at the dentist's.

This chapter is an attempt to understand the content of and motivation for a popular form of physicalism, which I call nonreductive physicalism. Nonreductive physicalism claims that although the mind is physical (in some sense), mental properties are nonetheless not identical to (or reducible to) physical properties. This suggests that mental properties are, in earlier terminology, emergent properties of physical entities. Yet many nonreductive physicalists have denied this. In what follows, I examine their denial, and I argue that on a plausible understanding of what emergent means, the denial is indefensible: nonreductive physicalism is committed to mental properties being emergent properties. It follows that the problems for emergentism – especially the problems of mental causation – are also problems for nonreductive physicalism, and they are problems for the same reason.

The structure of the chapter is as follows. In the first section, I outline what I take to be essential to nonreductive physicalism. In the second section I attempt to clarify what is meant by emergent, and I argue that the notion of emergence is best understood in terms of the idea of emergent properties having causal powers that are independent of the causal powers of the objects from which they emerge. This idea, ‘downward causation,’ is examined in the third section. In the final section I draw the lessons of this discussion for the contemporary debate on the mind-body problem.

There is a big difference between building a prototype system and a piece of production software. In his classic book The Mythical Man-Month, Fredrick Brooks estimates that it takes nine times the effort to create a complete, reliable system as opposed to an initial program that starts to do the job.

With Meena's graduation, I needed a fresh student to turn our prototype into a production system. I got to know Roger Mailler when he took CSE 214, undergraduate Data Structures, with me in the fall of 1997. Roger was the bored-looking student in the front row – too bright and knowledgeable to get very much from the course, but too disciplined to cut class or hide in the back. Roger finished first out of the 126 students in the course (by a substantial margin) and was untainted by a programming assignment cheating scandal that claimed many of his classmates.

Roger is an interesting fellow whose career path to Stony Brook followed a very non-standard course. His first attempt at college (at the Rochester Institute of Technology) was, to be charitable, unsuccessful. In one year at RIT he amassed a grade point average (GPA) of 0.96, where 4.0 is an A and 1.0 is a D. Any mammal with a pulse ought to be able to do better. Indeed, this is the lowest GPA I've ever seen sustained over a full academic year because students capable of such performance usually manage to get themselves expelled before the year is out.

Introduction

Classical logic—including first order logic, which we studied in Chapter 2—is concerned with deductive inference. If the premises are true, the conclusions drawn using classical logic are always also true. Although this kind of reasoning is not inductive, in the sense that any conclusion we can draw from a set of premises is already “buried” in the premises themselves, it is nonetheless fundamental to many kinds of reasoning tasks. In addition to the study of formal systems such as mathematics, in other domains such as planning and scheduling a problem can in many cases also be constrained to be mainly deductive.

Because of this pervasiveness, many logics for uncertain inference incorporate classical logic at the core. Rather than replacing classical logic, we extend it in various ways to handle reasoning with uncertainty. In this chapter, we will study a number of these formalisms, grouped under the banner nonmonotonic reasoning. Monotonicity, a key property of classical logic, is given up, so that an addition to the premises may invalidate some previous conclusions. This models our experience: the world and our knowledge of it are not static; often we need to retract some previously drawn conclusion on learning new information.

Logic and (Non)monotonicity

One of the main characteristics of classical logic is that it is monotonic, that is, adding more formulas to the set of premises does not invalidate the proofs of the formulas derivable from the original premises alone. In other words, a formula that can be derived from the original premises remains derivable in the expanded premise set.

Jai alai is a sport of Basque origin in which opposing players or teams alternate hurling a ball against the wall and catching it until one of them finally misses and loses the point. The throwing and catching are done with an enlarged basket or cesta. The ball or pelota is made of goatskin and hard rubber, and the wall is of granite or concrete – which is a combination that leads to fast and exciting action. Jai alai is a popular spectator sport in Europe and the Americas. In the United States, it is most associated with the states of Florida, Connecticut, and Rhode Island, which permit parimutuel wagering on the sport.

In this chapter, we will delve deeper into the history and culture of jai alai. From the standpoint purely crass of winning money through gambling, much of this material is not strictly necessary, but a little history and culture never hurt anybody. Be my guest if you want to skip ahead to the more mercenary or technical parts of the book, but don't neglect to review the basic types of bets in jai alai and the Spectacular Seven scoring system. Understanding the implications of the scoring system is perhaps the single most important factor in successful jai alai wagering.

Much of this background material has been lifted from the fronton Websites described later in this chapter and earlier books on jai alai.

Economists are very concerned with the concept of market efficiency. Markets are efficient whenever prices reflect underlying values. Market efficiency implies that everyone has the same information about what is available and processes it correctly.

The question of whether the jai alai bettors' market is efficient goes straight to the heart of whether there is any hope to make money betting on it. All of the information that we use to predict the outcome of jai alai matches is available to the general public. Because we are betting against the public, we can only win if we can interpret this data more successfully than the rest of the market. We can win money if and only if the market is inefficient.

Analyzing market efficiency requires us to build a model of how the general public bets. Once we have an accurate betting model, we can compare it with the results of our Monte Carlo simulation to look for inefficiencies. Any bet that the public rates higher than our simulation is one to stay away from, whereas any bet that the simulation rates higher than the public represents a market inefficiency potentially worth exploiting.

The issue of market efficiency rears its head most dramatically in the stock market. Billions of dollars are traded daily in the major markets by tens of thousands of people watching minute-by-minute stock ticker reports. Quantitative market analysts (the so-called quants) believe that there are indeed inefficiencies in the stock market that show up as statistical patterns.