The Metaphysics of Scientific Realism

Brian Ellis

• Publisher: Routledge
• Year: 2014
• Print ISBN:
  9781844652051
• eBook ISBN:
  9781317492191
• Topic: Philosophy
• Subtopic: Epistemology in Philosophy

This book presents a major statement on the dominant philosophy of science by one of the world's leading metaphysicians. Brian Ellis's new book develops the metaphysics of scientific realism to the point where it begins to take on the characteristics of a first philosophy. As most people understand it, scientific realism is not yet such a theory. It is not sufficiently general, and has no plausible applications in fields other than the well-established sciences. Nevertheless, Ellis demonstrates that the original arguments that led to scientific realism may be deployed more widely than they originally were to fill out a more complete picture of what there is. Ellis shows that realistic theories of quantum mechanics, time, causality and human freedom can all be developed satisfactorily, and moral theory can be recast to fit within this comprehensive metaphysical framework.

1 Science and Metaphysics

DOI: 10.4324/9781315711522-1

Truth is said to be what corresponds to reality. If this is so, then truth must be one thing, and reality another. Metaphysics, as I understand it, is an enquiry into the nature of this supposed reality. Presumably, such an enquiry, if it is possible at all, must start with whatever knowledge of the world we think we have, and consider what implications it may have concerning the supposed reality that gives rise to it. In this chapter it will be argued that an enquiry into the metaphysical implications of science is certainly possible, but is not itself part of science. For science is limited in what it can tell us about reality. What is needed, it will be argued, is not more science, but the progressive development of higher and higher levels of explanation of the world that is revealed to us by science. For the aims of metaphysics are different from those of science, and the structures of metaphysical explanations are different from those of scientific explanations. Metaphysical explanations all proceed from the premise that truth supervenes on being. And the general question being asked is: how does it supervene? Scientific explanations make no such assumption, and scientific enquiries usually stop short of asking this question.

Science is not limited, as the early positivists believed it to be, to just describing what can be observed, and constructing theories that will enable scientists to make sound predictions concerning future observations. Scientists do construct realistic theories about things, and some of them should certainly be taken seriously as descriptive of what there is. But not all theories are like this, and what many of them tell us about reality is unclear. There are also good reasons to think that there are essential limitations to scientific knowledge of the world, and that there are important questions that arise out of science about the nature of reality that cannot be answered by further scientific enquiry. Answering these questions is what metaphysics is all about.

Science can, in principle, tell us what is objectively true. But it cannot tell us whether, or if so how, these truths supervene on reality. It could, perhaps, if we had a good and workable correspondence, or metaphysical, theory of truth. But there is no such theory that is adequate to bear this metaphysical burden. Bertrand Russell’s correspondence theory does not do the job, for well-known reasons. And the much more highly developed semantic theory of truth cannot be taken seriously, even as a rough guide to metaphysics, unless you want to be a “possible worlds” realist. What is needed, I shall argue, is an enquiry into the truthmakers of science. And what will ultimately be needed is a theory of reality that will accommodate these truthmakers.

The truthmakers are the things, properties or states of affairs that exist in the world, independently of our knowledge or understanding of it, whose very existence necessitates everything that is objectively true about it. It is reasonable, therefore, to identify the task of metaphysics as being to identify the kinds of truthmakers there are for the various kinds of known truths about the world, and to construct an overall picture of reality that is adequate to accommodate them. As we shall see, truthmaking is different from entailing, because a truthmaker is never just another proposition. A truthmaker is an existent of some kind that necessitates the truth of whatever it supports.

In what follows, I shall give a personalized, and no doubt air-brushed, account of the reasoning that led me to these conclusions, and to embark on this project.

Scientific knowledge and its limitations

Science is limited by what scientists are able to do. In practice, it is restricted by lack of resources, failure to make the required observations and the intellectual limitations of scientists, and in other ways. But let us imagine a world in which all such limitations have been overcome, as if by magic, and let us call the theory of the natural world that science would ideally deliver in such a world “the scientific worldview”. Then, plausibly, this worldview has some claim to be considered the true one: the one at which we should ultimately aim. For, by definition, this is the view of reality that would rationally be accepted on the basis of the best and most comprehensive set of observations that human beings could possibly make. Nevertheless, most philosophers would probably say that even this ideal scientific worldview might not be true. There might be parts of reality that we cannot ever know about. Or, we might, either by accident or design, be systematically deceived about the nature of reality. Or, perhaps, we are just not biologically programmed in the right sort of way to discover the nature of reality – even in ideal circumstances. We can, no doubt, discover by scientific investigation many of the things that we (i.e. we human beings) ought rationally to believe, and rule out a great many things that it would ultimately be irrational for us to believe. So, even if there are limits to what it is possible for scientists to discover, the aim of discovering all and only those things that it would, in ideal circumstances, be rational for us to believe about the world would seem to be a plausible objective of scientific enquiry.

For many years, I assumed that these doubts about the limits of science reflected badly on the correspondence, or metaphysical, theory of truth that gave rise to them. I thought that many philosophers were just pretentiously wanting to play God, or see the world through the eyes of God. Consequently, I accepted the pragmatist theory that identifies truth with what it would ideally be rational to believe, and called myself an “internal realist’, as others before me have done. I embraced this position, because the empiricist in me identified science with scientific enquiry about the nature of reality. And, I did not believe that there was any other kind of rational enquiry that could take over where science left off, or that scientific knowledge about the world was essentially limited in any way; or, if it were, then these limitations were essentially human limitations that we, as human beings, could never overcome. There might be a theory of science, a logic of science or an enquiry into the language of science or into the various kinds of concepts employed in science. But these enquiries were not, I thought, continuations of the scientific quest to understand the nature of reality. They were just meta-scientific enquiries, that is, enquiries about the nature of scientific enquiry, which philosophers of science were at least as well equipped as anyone else to undertake. The idea that one could continue the enquiry into the nature of reality by rational means that were not essentially scientific was one that struck me as preposterous.

This stance was reinforced for me, first, by my conviction that an evaluative concept of truth was all that was required for logic. In Rational Belief Systems (1979), I demonstrated that the standard deductive logics, including all of the quantified, modal and conditional ones, could be founded adequately in a theory of rationality, without presupposing a semantic theory of truth, or assuming the existence of any world other than this one. All that one needed for the purpose were some more or less self-evident principles of rationality based on a conception of truth as epistemic rightness. Secondly, I was, at the time, convinced that science implied its own ontology. For, it seemed to me that one could not rationally accept the truth of any process theory in science without accepting the reality of the processes that it allegedly involved. This was the classic argument for scientific realism that Jack Smart had used to such good effect in his Philosophy and Scientific Realism (1963). And I thought then that one does not need to have a metaphysical theory of truth to accept it.

In retrospect, I now recognize that it was a mistake to reject the metaphysical concept of truth when I did. For I now see that there are important questions about the nature of reality that cannot, even in principle, be resolved by the methods of science. First, there are many statements that are apparently significant claims about what is true in the world, which have been, and still are, widely regarded as conventional. The claim that the one-way speed of light is the same in all directions is such a statement. Yet the special theory of relativity that is based on this claim is greatly superior to any alternative hypothesis. Non-standard versions of the special theory of relativity can certainly be constructed, but they are all very much more complex than the standard version, and all involve arbitrary asymmetries, not only in the laws of electromagnetic radiation, but also in the behaviour of slowly transported clocks (since standard clocks must be seen to be speeding up or slowing down, depending on their directions of motion).³

3. If slowly transported clocks are assumed to remain isochronous, then the laws of electromagnetic radiation will be found to be isotropic. Ole Rømer’s method of measuring the speed of light is one that is based on the assumption that clocks in this case, the clock that consists of Jupiter and its moons) remain isochronous as they are moved around slowly, relative to the speed of light. Accordingly, Rømer’s method must be regarded as a way of measuring the one-way speed of light by means of slow clock transport. Empirically, the speed of light measured in this way is the same whatever the location of Jupiter over its twelve-year cycle, and so, presumably, it is the same in all directions.

Therefore, if truth is, as I once defined it (1985: 169), just what has to be accepted as part of the best overall theory, and nothing more nor less, then the claim that the one-way speed of light is the same in all directions must be considered to be true. But, if it is true, then there is yet a further question that needs to be asked, although it is not one that can be answered by further scientific enquiry: what is it about reality that makes it true? And the answer you give to this can only depend on your metaphysics. If you believe in the Riemann/ Reichenbach thesis of the intrinsic metrical amorphousness of space and time, as Adolf Grünbaum (1973: 8–18) does, then you will deny that there is any truth of the matter. But if you believe in the isotropy of space from the perspective of every inertial system, then you must accept that there is a truth of the matter. For the standard version of the special theory of relativity is the only one that satisfies this metaphysical hypothesis.

In my dispute with the Pittsburgh panel (Ellis & Bowman 1967; Grünbaum et al. 1969; Ellis 1971), the metaphysical question concerning the nature of the reality reflected in the special theory of relativity was never explicitly discussed. Yet, in retrospect, it is now clear to me that this is what was at issue. Grünbaum et al. accepted the “metrical amorphousness” thesis, which they took to imply that there are no naturally preferred metrics, or kinds of metrics, of space or time. For them, a metric, that is, a way of measuring dates, time-intervals, positions, distances and so on, must depend ultimately on coordinative definitions, which, they argued, are always matters for human decision. Therefore, a metric has always to be imposed on space and time, not discovered of it. Indeed, they thought, nothing about the required metric could ever be discovered empirically, because there was no metric to discover. But I did not accept this. For I thought that a theory that did not postulate, unnecessarily, any spatial anisotropies, and led to what was clearly the simplest and best theory of space-time, was obviously the one that ought to be accepted. But I had no answer to, and did not think it was necessary to try to explain, what made it right metaphysically to believe in the independence of the one-way speed of light with direction. I could answer the epistemic question of rightness to believe, but I could not answer the metaphysical one. If Grünbaum et al. were right, then there could be no truthmaker for this proposition: so, even if it were true epistemically that the one-way speed of light is independent of direction, it would not be true metaphysically. I think now it is true both metaphysically and epistemically, but I do not expect the former to be an empirical discovery.

Secondly, I did not understand the full force of Smart’s argument for scientific realism until the mid-1980s, when I was asked to write something for a book of essays in Smart’s honour. I now think that Smart’s original argument for scientific realism requires much more than a kind of scientific entity realism, which is the variety of scientific realism that I advocated earlier. If one accepts realism about causal processes in the established sciences, and hence about the theoretical entities involved in them, then, by parity of reasoning, one should also accept realism about the causal powers that give rise to these processes, and about the spatiotemporal and numerical relations between things that characterize these processes, or the circumstances in which they occur. Or, if one does not wish to accept all of these things, then one must at least have a satisfactory reductive account of them.

Thirdly, I became convinced that, despite their good intentions, philosophers of science had erected many barriers to understanding the nature of reality. The principle of the metrical amorphousness of space and time is just one example. There are many others. It was, for example, fairly generally supposed that science had to be squeezed somehow into the straitjacket of a language with the structure of first-order predicate calculus. These languages, they thought, were adequate for stating everything that could be stated of a factual nature about the world. Modal languages, and languages with counterfactual conditionals, were the languages of “second-grade” discourse (as W. V. Quine described them), and were to be avoided. I thought, however, that these were precisely the kinds of languages required for scientific discourse, and that if these were not fact-stating languages, then so much the worse for the metaphysical thesis that science was concerned only with fact-stating. I thought, for example, that many of the laws of nature were universal counterfactual conditionals, that is, conditionals of the form: “If anything were an X in conditions of the kind C, then X would do Y, unless something interfered with it’! Others, I thought, were concerned with what is physically possible, or impossible, and so were stateable only in a modal language. Therefore, the requirements placed on acceptable analyses mostly seemed to me to be absurdly restrictive.

In the 1960s and 1970s, “possible worlds” semantics for modal and conditional languages were developed, and the requirement that science limit itself to fact-stating took on a whole new meaning. For the languages we could now use, and represent formally, were not limited in function to stating facts about what there is in the actual world. In these modal and conditional languages we could also state facts about what exists in any of the merely possible worlds, and say which of these possible worlds are accessible to which other worlds, and which are the “nearest” ones in which, say “p” is true. And, all of these worlds are, by definition, ones that could, in principle, be fully described in extensional, that is, fact-stating, languages: languages fit for “first-grade discourse’. Thus, the metaphysical pretence that the discoveries of science are limited to stating the facts could still be maintained. But victory was surely achieved at a very considerable cost to scientific realism.

As one who sought to derive ontology from science, it seemed clear to me that there are not, and could not be, any good reasons to believe that there are any merely possible worlds. There might conceivably be good reasons to believe that there are inaccessible parts of the actual world. But David Lewis had no such reasons. In Rational Belief Systems I demonstrated that there is a viable, and scientifically much more acceptable, alternative to Lewis’s theory, which is to develop the appropriate ideals of rational belief, and demonstrate that belief systems on languages that have connectives and operators of the kinds logicians are seeking to define are rational if and only if they are rationally coherent, given these ideals. This is what I thought any good scientist would seek to do. And it is precisely what I sought to do in my book. But philosophers had long rejected this approach as “psychologistic”. And, “psychologism”, as nearly everyone knows, is a very dirty word. So, rather than try to come to terms with my approach, most philosophers just ignored it. In doing so, I contend, they deprived themselves of the only plausible explanation that anyone has ever been able to give of the usefulness of the fiction about “possible worlds” implicit in modal semantics.

To illustrate, if we wish to consider an ideally rational belief system that is as much like our own limited one as we can make it, but in which p is accepted as true, then we may easily do so, even if we ourselves believe that not-p. And, we may then use the theory of rational belief systems to determine whether q could rationally be denied in such a system. If not, then, according to the theory, the conditional “p ⇒ q” must rationally be accepted as true.

In general, to found a satisfactory propositional logic, or a predicate calculus, or to introduce modal operators and conditional connectives into a logical system, all one needs to do is develop appropriate axiom systems for rational belief systems on languages that have the relevant connectives and operators, and, effectively, to define them by the acceptability conditions for propositions that include them. Thus acceptability conditions can replace truth conditions in the foundations of logic, and ideally completed rational belief systems can replace possible worlds in the theories of modals and conditionals. And, the only price one has to pay for this is that one has to abandon the implausible Fregean idea that logic is the theory of truth preservation.

Where Gottlob Frege got this idea from is not entirely clear. But it seems to be implicit in the writings of René Descartes, who himself appears to have got it from Aristotle. In his Posterior Analytics, Aristotle distinguished two grades of knowledge, scientific and accidental. Accidental knowledge, he said, is knowledge gained by experience, that is, empirical knowledge. But for scientific knowledge, he said, we require knowledge of the cause on which a fact depends, “as the cause of that fact, and no other” (71b, 11). And, to have such knowledge, he said, we must have a demonstration of the fact from premises that are “true, primary, immediate, better known than, and known prior to, that which is to be demonstrated“ (71b, 21–2). Descartes echoed this idea in the seventeenth century in his Discourse on the Method of Rightly Directing One’s Reason and of Seeking Truth in the Sciences, commonly known by the abbreviated title Discourse on Method. To quote:

Those long chains of perfectly simple and easy reasonings by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what is not, and always preserve the right order for deduction of one thing from another, there can be nothing too rem...

Table of contents

• Cover Page
• Half Title Page
• Series
• Title Page
• Copyright Page
• Dedication
• Contents
• Preface
• Introduction
• 1 Science and Metaphysics
• 2 The Ontology of Scientific Realism
• 3 Essentialist Realism
• 4 Quantum Mechanical Realism
• 5 Causal Powers and Categorical Dimensions
• 6 Realism As First Philosophy
• 7 Realism in Ethics
• reference
• Index