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  13.3A Perceptual Realism. 13.3A.1T Indirect Realism.

  13.3A.1A Direct Realism. 13.3A.1A.1T Perceptual Dualism.

  13.3A.1A.1A Unitary Direct Realism.

  In other cases, the metaphysical theories that share a common commitment cannot be simply divided in a binary way, based on their position on some one subsidiary issue. Instead, there may be three or more different ways of making a given position more determinate. In those cases, we follow the name of a thesis with a period and a numeral (1, 2, 3, or 4), without adding any additional T's or A's. For example, we break down Reductive Nominalism (8.1T) into four sub-theories:

  8.1T.1 Predicate Nominalism

  8.1T.2 Concept Nominalism

  8.1T.3 Class Nominalism

  8.1T.4 Resemblance Nominalism

  THE TABLE OF METAPHYSICAL PRINCIPLES A second ambition that we have for the book is to keep track with great care the metaphysical first principles that we appeal to in developing arguments for or against a particular position. We have listed all of the metaphysical principles that appear in more than one section of the book in Appendix B. The principles are divided into six major categories: principles of methodology (PMeth 1 through 4), principles of knowledge or epistemology (PEpist 1 through 5), principles of truth (PTruth 1 and 2), principles of metaphysics (PMeta 1 through 6), principles of natural philosophy (PNatPhil 1 and 2), and axioms of mereology, the formal theory of parts and wholes (MA 1 through 6), for a grand total of 25 principles. Some of the principles take more than one form or are associated with a number of corollaries. The first principle of methodology, Ockham's Razor, has six corollaries (and one addendum), while the second principle, scientific realism, takes two distinct forms, objectivity (PMeth 2.1) and reliability (PMeth 2.2).

  There are also a number of other first principles that occur only once in the text: these are always given a name (distinguished by boldface type). Chapter 29, the final chapter, includes a table in which the principles appealed to by each of four philosophical “packages” are listed. The four packages, Aristotelian, Ludovician (for David Lewis), Fortibrachian (for David Armstrong), and Flatlander (for Quine, Chisholm, Plantinga, and van Inwagen), represent bundles of philosophical theses and antitheses that cohere together naturally in terms of their rationales and methodological commitments, as the table helps to reveal.

  THE ORGANIZATION OF THE BOOK This book is divided into eight parts, with a total of 29 chapters. The first three chapters, including this one, are introductory in character. Chapters 2 and 3 introduce the two notions of truthmaking and of grounding, ideas that lie at the heart of a significant number of metaphysical projects. They can be skipped by those who are willing to plunge into the project of positive metaphysics, armed only with an intuitive grasp of such notions as something's making a proposition true, or of one truth holding in virtue of or wholly grounded by another. The chapters provide useful details about the methodological foundations of much of the rest of the text.

  Part II comprises three chapters, each developing an account of dispositions: conditionals (Chapter 4), laws of nature (Chapter 5), and intrinsic powers (Chapter 6). This part is really foundational for the rest of the book and cannot be omitted.

  After completing Chapter 6, the reader can take a number of different paths. Part III, on universals and particulars, is largely independent of the rest of the book, as is Part IV, on the scope of existence and the question of idealism. Parts V and VI, on modality (possibility and necessity) and space and time, are highly interdependent and should ideally be read as a unity. The final two parts, VII (on the unity of things) and VIII (on causation), depend on much of what has gone before them and should be read at the end, as should the conclusion, Chapter 29.

  We have also written a much shorter introduction to metaphysics, Metaphysics: The Fundamentals (Wiley-Blackwell 2015), which could serve very well as an introduction and orientation to this volume. In almost every case where there is overlap between the two volumes, we go into more detail and consider more theoretical alternatives in this volume. Our discussions in Part IV and of the structure of space and the nature of causation are almost entirely without precedent in the earlier work. Metaphysics: The Fundamentals contains a final chapter (“The Concluding Unmetaphysical Postscript”) in which we defend metaphysics against various skeptical challenges. We assume, in this volume, that our reader has already exorcised such skeptical demons.

  To return to the organization of this volume, in Part III, we turn to four chapters on the ancient problems of universals and particulars. Chapter 7 includes our treatment of the arguments for and against the existence of universals—things that are common to things that are similar to one another. Chapter 8 examines the alternative view of Nominalism, according to which everything real is particular and unshareable, including the form of Nominalism that posits individualized properties or tropes. In Chapter 9, we consider the internal constitution of ordinary things and the ways in which they can be distinguished from one another. We take up the special case of relational and quantitative properties in Chapter 10.

  Part IV includes three chapters in which we consider theories about the nature of reality as a whole. We look first (in Chapter 11) to the question of how many things exist: none, one or more than one? Then, we consider (in Chapter 12) the place in reality of the non-existent, the merely possible, and the impossible. Finally, we examine (in Chapter 13) the case for supposing that all of reality is fundamentally mental or ideal by looking carefully at the structure of human sense perception.

  In Part V, we take up the questions of modality: necessity, possibility, contingency, and actuality. Chapter 14 contains our treatment of David Lewis's theory of possible worlds as concrete, material universes. In Chapter 15, we examine the opposing view, according to which possible worlds are abstract representations, properties or states of affairs. Chapter 16 concerns the problems of de re possibility, the realm of possibility that concerns the potentialities of particular things rather than of the whole world, and of our knowledge of modality.

  We deal in Part VI with the nature of space and time, with two chapters devoted to space and three to time. In Chapter 17, we consider whether space is a thing in its own right or whether it consists merely in the holding of spatial relations between bodies. We look in Chapter 18 at the structure of space: whether it consists fundamentally in dimensionless points or in extended regions. In Chapter 19, we ask similar questions about the structure of time: does it consist primarily of durationless instants or in extended periods? Chapters 20 and 21 concern two competing theories about the flow or passage of time, the A and B Theories. According to the A Theory, the differences between past, present, and future are absolute and fundamental, while for the B Theory the differences consist entirely in differences in one's perspective from within time.

  In Part VII, we take up the question of the unity of things, both at one time and through time. Chapters 22 and 23 concern the unity of composite things, things made up at a single time of many distinct parts. When do things make up a single whole (Chapter 22), and what is it for them to do so (Chapter 23)? The next two chapters concern the unity of things that persist through change and time. We take up the nature of change in Chapter 24 and the nature of those things that persist through change in Chapter 25.

  The final part, Part VIII, concerns the metaphysical problems of causation. In Chapter 26, we consider the question of whether causation exists at all. Assuming there is such a thing as causation, we must then consider what things does causation relate: truths or concrete events? Is it a relation between existing things or merely a logical relation between truths (Chapter 27)? Finally, we examine the relations between causation and time in Chapter 28. How do earlier events influence later ones: by a direct connection across time, or by being part of a single, temporally extended process?

  The book concludes with Chapter 29, in which we describe the four competing philosophical packages that have emerged in the course of
the rest of the work.

  Importantly, the reader should be aware that the divisions in the book are not meant to demarcate disconnected sub-fields of metaphysics, but are rather helpful divisions that make the metaphysical task a bit more manageable. One's views in one area can impact one's views in another; we do our best to make those connections clear when they are especially important. Further, and maybe more importantly, there are rarely if ever deductive arguments with unassailable premises for or against a metaphysical position. What one is faced with, rather, is a stock of evidence that one must weigh in order to form a considered opinion. Therefore, one must not only think about the evidence for and against a particular system but also make comparative judgments about which system does best on the evidence taken together. This is very difficult to do well, especially in light of the explosion of activity in metaphysics in recent years, and the interconnectedness of the various regions in that sprawl.

  There are two important consequences of this picture of metaphysics. First, the reader who has yet to form views in one or another area would do well to abstain from forming an opinion in that area until she has fully digested the connections to other areas and the strengths and weaknesses of views there. And second, despite the length of this book, we have been unable to carry every dispute to its furthest boundaries. We truncate the journey, sometimes by a good deal, in almost every direction. For those readers committed to a view that is underexplored or shortchanged, we ask your forgiveness.

  2

  Truthmakers

  2.1 Introduction

  Metaphysics is at least an attempt to build a theory that makes sense of many of the more abstract and general features of reality. Metaphysicians try to understand which things are fundamental, those things' natures, and the fundamental ways those things relate to one another. But where does one start such an endeavor?

  There is no generally accepted answer to that question, and so we start with a mundane yet fruitful observation: we say and write lots of truth-evaluable things. That is, we say and write things that have a truth-value, usually if not always either True or False. We can and regularly do say all sorts of true things. We also can and regularly do say all sorts of false things. Putting these two together, we can note that ‘Grass is green’, ‘Some trees are over one hundred feet tall’, ‘Two plus two is five’, ‘Kicking puppies for no reason at all is morally good’, and ‘Either the Triune God of Christianity exists or he doesn’t' are all either true or false.

  We can take this mundane observation, however, and put it to work. Philosophers have long argued about how to understand the nature of truth; that is, they have argued about how it is that a sentence comes out true or false. Here is how Aristotle put it in his Metaphysics:

  [Thus] we define what the true and the false are. To say of what is that it is not, or of what is not that it is, is false, while to say of what is that it is, and of what is not that it is not, is true. Metaphysics 1011b25–8

  (Aristotle 1984: 1597)

  Aristotle might naturally be taken to be suggesting that a sentence is true whenever the world is the way that the sentence says it is. The sentence ‘Grass is green’ is true, according to this suggestion, if and only if grass really is green. Any view of truth that incorporates this suggestion as a central feature is a Correspondence Theory of Truth. A Correspondence Theory is one that claims a sentence is true if and only there is a match, a correspondence, between what a sentence says and the world. Different Correspondence Theories are distinguished by their respective takes on what “matching” or “correspondence” consists in.

  There are two sides to this simple correspondence story. We can picture the view as in Figure 2.1.

  Figure 2.1 The Correspondence Relation

  The first side of the correspondence story involves the sentence and what it says about the world. The second side is the world itself. We'll say a bit about the first side and then turn to a more sustained discussion of the second. In both cases, the task is to say something more careful and deep about the natures of the items on either side of such a correspondence relation.

  2.1.1 Propositions

  The first way that a discussion of truth gets one going in metaphysics is via its connection to propositions. Propositions, according to standard philosophical lore, are the meanings of (many, most, or all) assertoric (indicative) sentences and are the objects of belief and knowledge (and maybe other mental attitudes like desire). The idea is that a sentence token, say a token utterance of ‘Texas is super-duper’ expresses a proposition, that Texas is super-duper.1 This proposition represents the world as being a certain way. (More on representation below.)

  If the world is as the proposition represents the world as being, if Texas really is super-duper, then the proposition is true and, thereby, so is the sentence token that expressed it. The truth or falsity of a sentence token, on this view, is derivative of the truth or falsity of the proposition it expresses. Similarly, a token belief is a relation to a proposition that functions as the content of that belief, and again, that proposition represents the world as being a certain way. One might, for example, believe that Texas is super-duper or believe that Southern California is overcrowded. These beliefs are relations to the propositions that Texas is super-duper and that Southern California is overcrowded, respectively. As with sentences, beliefs are derivatively true or false in virtue of the truth or falsity of the propositions that are their contents.

  Propositions are standardly taken to be both non-linguistic and representational. Indeed, these two features are crucial to propositions playing their characteristic roles in language and thought.

  To motivate the idea that propositions must be non-linguistic, consider the possibility of not introducing propositions at all. You might think that sentences can do anything that propositions can do, like being the contents of language and thought and being the fundamental bearers of truth-value. If so, one could simply cut out the propositional middle man. However, there are two reasons why philosophers have thought it necessary to posit propositions in addition to sentences, and crucially, both reasons plausibly demand a non-linguistic object to serve as the content of language and thought. First, sentences in different languages can mean the same thing, and second, native speakers of different languages can share belief contents. Two people who speak different languages can express the same idea. For example, ‘Grass is green’ means in English just what ‘L’herbe est verte' means in French. These two sentences express the same proposition. If this is the case in general, then sentences cannot themselves function as meanings because sentences are language-bound but meanings appear not to be. Similarly, two people who natively speak different languages can have thoughts with the same content. Consider a native English speaker who has a thought she would express with the sentence ‘Grass is green’ and a native French speaker who has a thought he would express with the sentence ‘L’herbe est verte'. These two thoughts have the same content, the same meaning. For the same reason, therefore, sentences cannot function as the meanings of these thoughts because sentences are language-bound but contents appear not to be. In light of the inability of sentences to serve as meanings for sentences and contents for thoughts, philosophers often postulate propositions.

  We can turn these two observations into reasons to think that propositions must be non-linguistic. Suppose that propositions, like sentences, were language-bound objects. If so, the English sentence ‘Grass is green’ would express an English-proposition, and the French sentence ‘L’herbe est verte' would express a French-proposition. But that can't be right, for the same reason that sentences cannot function as meanings: these two sentences express the same proposition! Thus, for propositions to function as meanings, they must be non-linguistic.

  In addition to being non-linguistic, propositions must represent the world. This is necessary in order to explain, for example, how it is that we have true and false beliefs and how it is that we say true and false things. Propositions have
representational properties in virtue of which they can be accurate or inaccurate. These representational features are something like the representational features of a realist painting, drawing, or sculpture or like the representational features of a photograph. Insofar as an artist is attempting to mirror the features of the world in his or her art, the resulting piece can be evaluated for its accuracy. In a similar way, beliefs and sentences represent the world in virtue of their relationships to propositions. Beliefs are true or false because they have propositions as their content, propositions that represent the world accurately or not; the sentences we use are true or false because they express propositions that represent the world accurately or not. See Figures 2.2 and 2.3.

  Figure 2.2 Propositions as Contents of Sentence Tokens

  Figure 2.3 Propositions as Contents of Attitude States

  The representational features of propositions are plausibly different from the representational features of realist artwork and photographs, however, in at least two ways: (i) propositions represent what they do independently of the intentions of conscious agents, and (ii) propositions do not represent by being similar to that which is represented. One important metaphysical question that arises at this stage, then, is just how it is that propositions represent what they do. Another metaphysical question arises as well: what, exactly, are propositions? So far, we have identified two features of propositions that constrain what sort of thing a proposition could be. They must be non-linguistic and representational. Further, we have given propositions two roles to play, namely, being the meanings of (at least many) assertoric sentences and the contents of belief (and other mental attitudes).2 But this leaves open the question of what sort of non-linguistic, representational thing propositions are. These two questions are importantly interrelated. By answering the second one may find that one has arrived at, or anyway constrained the possibilities regarding an answer to the first.