From Truth to Reality

New Essays in Logic and Metaphysics

Heather Dyke

• Publisher: Routledge
• Year: 2009
• Print ISBN: 9780415988452
• eBook ISBN: 9781135246907
• Topic: Philosophy
• Subtopic: Logic in Philosophy

Questions about truth and questions about reality are intimately connected. One can ask whether numbers exist by asking "Are there numbers?" But one can also ask what arguably amounts to the same question by asking "Is the sentence 'There are numbers' true?" Such semantic ascent implies that reality can be investigated by investigating our true sentences. This line of thought was dominant in twentieth century philosophy, but is now beginning to be called into question.

In From Truth to Reality, Heather Dyke brings together some of the foremost metaphysicians to examine approaches to truth, reality, and the connections between the two. This collection features new and previously unpublished material by JC Beall, Mark Colyvan, Michael Devitt, John Heil, Frank Jackson, Fred Kroon, D. H. Mellor, Luca Moretti, Alan Musgrave, Robert Nola, J. J. C. Smart, Paul Snowdon, and Daniel Stoljar.

1 Introduction

Heather Dyke

Questions about the nature of truth are as old as philosophy itself. What is truth? On the one hand, it seems obvious that it is something that applies to the things we think and say. Many of our beliefs about the world, and sentences describing it, are true. On the other hand, it seems intimately connected with the world we think and speak about, for it is in virtue of the way the world is that our sentences and beliefs about it are true. This book explores the notions of truth, reality, and the many connections between them.

There are philosophical questions that are primarily about truth. What, for example, are we to say about the truth-value of the sentence “This sentence is not true”? If true, then it says something false, but if false, it says something true. Do sentences that contain vague predicates have a determinate truth-value? If not, are there three truth-values: true, false, and neither-true-nor-false, or are some sentences both true and false? Then there are philosophical questions that are primarily about reality. Does reality contain numbers, universals, abstract entities, unobservable entities posited by science? But questions about truth and questions about reality can also be intimately connected. One can, for instance, ask whether reality includes numbers by asking “Are there numbers?”. But one can also ask what (arguably) amounts to the very same question by asking “Is the sentence ‘There are numbers’ true?” By performing this “semantic ascent,” the nature of reality, it seems, can be investigated via an investigation into our true sentences. Moreover, this seems like a tempting shortcut, as it is far easier to infer the existence of numbers from the truth of sentences about them than it is to engage in metaphysical investigations into the question of their existence. That semantic ascent was a legitimate methodology in metaphysics was very much taken for granted in twentieth-century philosophy, but it is now beginning to be called into question (see, for example, Heil 2003 and Dyke 2007). Just how much can we learn about the nature of reality by investigating our true sentences? Does, for example, the truth of “There is a prime number between ten and twenty” mean that prime numbers exist? Does the truth of “Eating people is wrong” mean that moral properties exist? Does, to use a more commonplace example, the truth of “Spiders give me the creeps” mean that the creeps exist?

The chapters in this volume are divided into three sections, roughly in line with the three types of question described above, viz., those about truth, those about reality, and those about the area where truth and reality meet. In the remainder of this introduction I give an overview of the themes and issues raised by each of the chapters, while illustrating how they interweave with each other.

TRUTH

There is a prima facie tension between the intuitively attractive principle of bivalence—that every proposition is either true or false—and the fact that many ordinary, everyday propositions appear to be neither true nor false. For example, suppose Bob’s hair is starting to recede. Bob is not yet bald, but he’s not quite not bald either. So, is the sentence “Bob is bald” true or false? Well, it’s not obviously true, but neither is it obviously false, so the option of responding “neither” is at least tempting. And yet propositions that contain vague predicates and are about apparent borderline cases are ubiquitous. What are our options here? Well, we might want to say that there is a determinate answer to the question of whether or not Bob is bald. This would involve accepting that there is a sharp cutoff point between being bald and being not-bald and, thus, ultimately rejecting the claim that there are genuinely vague predicates. But it seems implausible to accept that there is a certain number, n, such that if one has n or more hairs on one’s head one is not bald, but if one has fewer than n hairs on one’s head one is bald. We could sweeten this pill by adding that, although there is a sharp cut-off point for the applicability of some of our predicates, we do not know, or perhaps could not know, what that cut-off point is. According to this view, which is held by, for example, Williamson (1994), the gaps are epistemic; they concern our lack of knowledge about where the cut-off points for the applicability of our predicates lie. Another option is to reject bivalence and hold that some propositions are neither true nor false.

JC Beall, in his chapter for this volume, wishes to endorse both bivalence and the common-sense claim that there are apparent “gaps” in our language. He introduces the notion of unsettled predicates, which are those for which our linguistic practice has established only a sufficient but not a necessary condition for satisfaction. Thus, we can say with certainty that if Bob has fewer than n hairs on his head then he is bald, but as there is no necessary condition for the applicability of the predicate “is bald,” it doesn’t follow that if he has more than n hairs on his head he is not bald. Thus, Beall’s proposal allows for, indeed explains, the presence of gaps in our language, but these are not, he insists, standard gaps, but rather “star gaps” that arise from the distinctive sufficient-condition-only practice that governs vague terms.

Vagueness and the apparent gappiness of language give rise to sorites paradoxes. If Bob has 100,000 hairs on his head then he is not bald. It seems reasonable to accept that the loss of a single hair will not render a hirsute man bald. Thus, if we remove a hair from Bob’s head so that he has 99,999 hairs on his head, he is still not bald. But we can continue removing hairs from Bob’s head one at a time until eventually he has but a single hair left. Is he then bald or not bald? Following our process of reasoning we are forced to conclude that he is not bald, but common sense would insist that he is. Similar sorites paradoxes can be constructed for any vague term, such as “is tall,” “is a heap” and “is an adult.”

Sorites paradoxes form part of the focus of Colyvan’s chapter. He argues that the sorites and liar paradoxes are of a kind and so should submit to a uniform solution. He discusses the principle of uniform solution, according to which similar paradoxes should admit of similar solutions. But how do we decide when two paradoxes are of a kind and so should be treated similarly? Colyvan suggests three legitimate means of establishing similarity between paradoxes. He goes on to argue that, though the liar and the sorites may not be structurally similar, they do meet his other two criteria for establishing similarity. They both have close neighbors—their respective strengthened forms: the strengthened liar and the higher-order sorites. Furthermore, these nearby neighbors play similar roles in the dialectic against gappy solutions to their respective original counterparts (and for glutty solutions). In addition, he suggests, both the liar and the sorites respond to gappy approaches about as well as to each other and that gap solutions have serious difficulties with strengthened forms. Is this enough? Perhaps these similarities are indicative of a deeper underlying structural similarity. That would be the topic for a further investigation. But Colyvan, like Beall, has suggested a modest new proposal to deal with a very old problem about truth.

REALITY

Questions about reality are, on the face of it, very different from questions about truth. Their subject matter is the world, not the language we use to talk about the world. However, some philosophers, most notably Dummett (1959, 1991) have characterized the realism/antirealism debate in semantic terms, with the central notion being a principle that looms large in our chapters on truth: bivalence. If one is a realist about some subject matter then, according to Dummett, one must think that every claim about that subject matter is determinately either true or false. Indeed, Dummett often characterizes realism about a given subject matter in terms of accepting bivalence about that subject matter.

Michael Devitt is famous for rejecting attempts like Dummett’s to characterize realism as a semantic doctrine. He asks, “What has truth to do with Realism? On the face of it, nothing at all. Indeed, Realism says nothing semantic at all beyond, in its use of ‘objective’, making the negative point that our semantic capacities do not constitute the world” (Devitt 1997, 39). According to him, realism consists of two “dimensions”: the existence dimension, and the independence dimension. Together these two dimensions assert that the world (that is, the objects of common sense and science) exists objectively and independently of the ways we think about it and describe it (Devitt 1997, 23).

In his chapter for this volume, Devitt applies his finely honed views about realism and truth to the domain of biological concepts and discourse, in particular, to the species concept. To the existence and independence dimensions of realism in the biological domain he adds a further relevant issue: that of explanatory significance, which captures whether a kind of entity posited by a theory plays a causally significant role. He then characterizes explanatory realism as realism that requires mind-independent existence and explanatory significance. He also distinguishes between realism about the species category (that there are such things as species) and realism about species taxa (that there are such things as tigers, for example). Thus, an example of explanatory realism about species taxa might be that tigers exist, and it is explanatorily significant that they are tigers. Explanatory realism about the species category, on the other hand, asserts that species exist mind-independently, and it is explanatorily significant that they are species.

With his concepts and definitions thus marshalled, Devitt examines the views of two biological antirealists: Marc Ereshefsky (1998) and Kyle Stanford (1995). Ereshefsky is an antirealist about the species category. According to Devitt, that means that he does not think that the species category exists and is explanatorily significant. Ereshefsky sees himself as denying the existence of the species category, but Devitt argues that his argument is better understood as denying the explanatory significance of the species category. Ereshefsky bases his argument on evidence for pluralism about the species category: the view that there are several equally good accounts of what it is to be a species. But he does not question the existence of those organisms that we would ordinarily classify as tigers, elephants, or cabbages. Stanford’s antirealism is much more extreme. He denies the mind-independence of species. But, Devitt argues, his position “rests on a spurious inference from the theory-ladenness of judgments to the theory-ladenness of the world” (Devitt, this volume, 65).

According to Stanford, “judgements of what is biologically interesting can only be made relative to a particular time and theoretical context” (1995, 80–81), or, in other words, biological judgments are theory-laden. But Stanford takes this to imply that species themselves are theory-laden; that is, their very existence is dependent on the theoretical context from within which we make judgments about them. As Devitt remarks, this inference, although common, is exceedingly bad. It is an instance of what Alan Musgrave (2001 and this volume) calls “word magic,” of thinking that we can make things (species, for example) with words, and of what I have called the “representational fallacy” (Dyke 2007), of thinking that it is legitimate to infer metaphysical conclusions from premises purely about language. Devitt’s contribution to this volume is thus both a discussion of the nature of biological realism and antirealism and a lesson in avoiding familiar pitfalls when considering a new domain.

The chapters by Musgrave and Heil continue the theme touched on by Devitt of railing against what Heil calls “linguisticized metaphysics”: the tendency to be too quick to read one’s metaphysics off language. Musgrave’s target is Platonism, according to which abstract entities exist. He thinks belief in abstract objects of any kind is wrongheaded and that people only believe in them because they are tricked by language into doing so. His particular target in this volume is what he calls “pleonastic platonism,” the view espoused by Schiffer (1996) that we can arrive, via pleonastic transformation of sentences such as “Fido is a dog” to “Fido has the property of being a dog,” at the existence of entities such as properties. Other pleonastic transformations will lead us to other entities: propositions, events, states, and so on. Pleonastic entities are characterized by the following three features: they are language-created, by means of pleonastic transformations; the terms referring to them are guaranteed of reference; and to learn of their existence and all there is to know about them, one need only adopt the relevant language game (Thomasson 2001, 320). Musgrave argues that nothing has the three features allegedly possessed by pleonastic entities.

The move from “Fido is a dog” to “Fido has the property of being a dog” does not, according to Musgrave, license the conclusion that properties exist. To think it does is to succumb to word magic: the idea that once we invent a word or phrase we thereby create an entity for it to stand for. Musgrave’s alternative recommendation is to treat “Fido has the property of being a dog” as a long-winded or idiomatic way of saying “Fido is a dog.” These two sentences are not equivalent in meaning, but they do have the same truthmaker. The fact that Fido is a dog makes “Fido is a dog” true, and it also makes “Fido has the property of being a dog” true. Heil makes a similar point with respect to mental and physical descriptions. A mental description such as “Bob is in pain” might have the same truthmaker as some physical description such as “Bob is in brain state B.” Accepting this involves no commitment to the claim that these two descriptions have the same meaning or that one is linguistically reducible to the other. All it requires is that one reject the view that predicates correspond one-to-one with properties. Just because a predicate, such as “being in pain,” truly applies to some entity, it doesn’t follow that there is a property uniquely answering to that predicate, which is possessed by all entities to which that predicate applies, and in virtue of which that predicate applies to those entities. To think that the applicability of a predicate to an entity automatically gives rise to the existence of a property uniquely answering to that predicate is to engage in word magic.

But it is important to see that rejecting the idea that predicates correspond one-to-one with properties does not make the world mind- or language-dependent. As Heil says,

the world is ‘out there’ waiting to be considered and described by conscious agents. The significance of our predicates depends on us. It is a contingent fact about us that we use the predicate ‘is red’ to pick out redness, and not greenness, or saltiness, or triangularity. But this in no way makes redness, greenness, saltiness, or triangularity language- or mind-dependent (Heil, this volume, 97).

To think otherwise is to conflate the linguistic and the nonlinguistic; to move from observations about descriptions of the world to claims about the world itself. This is a mistake that both Heil and Musgrave wish to draw attention to and exhort philosophers to avoid at their peril.¹

The focus of Heil’s chapter is Donald Davidson’s monism about mental and physical properties (Davidson 1970b). Heil argues that Davidson has been disastrously misunderstood by many of his critics, who attribute to him the sort of one-to-one correspondence of properties to predicates just described. Heil outlines a kind of neutral monism that distinguishes the mental and the physical at the level of predicates but not in the reality answering to those predicates. He then attributes this view to Davidson. Heil’s Davidson sees the division of mental and physical as a surface distinction that operates at the descriptive level. Davidson as interpreted by his critics, notably Jaegwon Kim, sees this distinction as much more metaphysically robust. Kim trades in talk of predicates for talk of properties and, consequently, sees Davidson’s anomalous monism as a thesis concerning mental properties and the relations these bear to physical properties. Heil argues that it is wrong to see Davidson as holding that mental predicates designate mental properties, and physical predicates designate physical properties.

Heil restates Davidson’s thesis in terms of truthmakers, the topic of Mellor’s contribution to this volume. According to Heil, we should interpret Davidson’s monism as the view that the truthmaker for a mental description will always answer to some physical description. But it is important to see that it does not follow from this that there is any chance of translating or analyzing mental terms into a purely physical vocabulary. Heil then goes on to argue that, when his thesis is restated in this way, many criticisms of Davidson can be seen to miss the mark. Heil’s chapter is ultimately a lesson in how things can go wrong when we conflate the linguistic with the nonlinguistic or when we are too quick to draw metaphysical conclusions from what are essentially linguistic considerations.

Like Heil’s, Jackson’s chapter is about properties, in particular, which ones exist. But Jackson takes a rather different approach than that of Heil and Musgrave. Where they argued that truths of a certain sort give us no reason to believe in the existence of properties answering uniquely to the predicates contained in those truths, Jackson argues that the fact that what counts as evidence for one truth does not count as evidence for another permits us to conclude that those truths are not about the same things. For example, evidence for believing that someone is in pain is not evidence for believing that their C-fibers are firing so, Jackson concludes, being in pain is not identical to having one’s C-fibers firing. One might wonder whether Jackson has succumbed to the mistake that Heil and Musgrave warn us against of thinking that predicates and properties line up one-to-one, but in his sequence of objections and replies, Jackson argues that this is not the case. He is willing to accept that concepts and properties do not line up one-to-one, even that concepts outrun properties, but insists that this will not avoid the argument. The reason he gives for this is that “to believe that something falls under a given concept is to believe that it is a certain way, and this means that concepts don’t float free of properties” (Jackson, this volume, 104). Jackson’s argument does not proceed from the difference between the concepts of being in pain and having one’s C-fibers firing to the conclusion that pain is not identical to C-fibers firing. If it did it would succumb to the criticisms of Heil and Musgrave. Instead it proceeds from the difference in what counts as evidence for believing that someone is in pain and what counts as evidence for believing that someone’s C-fibers are firing.

Smart’s chapter addresses the age-old philosophical question of the ontological status of mathematical entities. Are there mathematical entities, such as numbers, that are neither spatiotemporal nor causal? Or are the truths of mathematics to be accounted for in some other way? Smart finds himself torn between a Quinean platonism and a desire that mathematics not be beholden to physics. He explores some of the alternatives, such as nominalism and fictionalism, but in the end is drawn to the conclusion that we ought to take the referring expressions of mathematics at face value.

TRUTH AND REALITY

The section on issues where the notions of truth and reality meet begins with a chapter by Luca Moretti on minimalism, or more specifically, creeping minimalism, which is a general tendency to adopt a minimalist attitude in various philosophical fields. Minimalism is, on the face of it, a doctrine about truth. It is the view that asserting that some clai...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• List of Contributors
• Acknowledgments
• 1 Introduction
• PART I: Truth
• PART II: Reality
• PART III: Truth and Reality
• References