This Is Metaphysics. Kris McDaniel

that, in general, metaphysical claims connect in intricate and important ways with other metaphysical claims, and that it benefits a reader to see this. Metaphysical questions are very hard to answer conclusively, but this isn’t because there are no answers to them. Rather, one reason they are hard to answer is that while attempting to answer one metaphysical question, you almost always end up having to answer many others in the process. Probably we will never run out of metaphysical questions to answer.

0.40 At the end of each chapter is a section titled Doing Metaphysics that contains further questions that the student might be wish to ponder or the instructor might wish to discuss in class. This section also contains recommendations for further reading.

0.5 Acknowledgments

      0.41 I thank Elizabeth Barnes, Ross Cameron, Cody Gilmore, Carrie Jenkins, Brad Skow, Jennifer Saul, and Jason Turner for looking at chapters in this book and giving me very useful comments. Jeremey Dickinson, Steve Hales, Hud Hudson, and Joshua Spencer read through entire drafts and gave me very useful feedback on each chapter. I also had great comments from three anonymous referees. Byron Simmons provided me excellent philosophical comments and also edited the penultimate draft of the book; he did a splendid job. Finally, Steve Hales was a very patient editor even though I was a very annoying author to work with.

      Note

      1 1 http://looksphilosophical.tumblr.com/

1 CLASSIFICATION

      1.1 Introduction

      1.1 This chapter focuses on the common‐place activity of distinguishing and classifying objects of various kinds. You might wonder: Why start a book on metaphysics with a discussion of classification?

      1.2 There are a couple of reasons. First, lurking behind this common‐place activity are a lot of metaphysical puzzles and questions! One of the cool things you’ll discover as you study metaphysics is that the world is a lot more complicated and much stranger than you initially might have thought. A good way to illustrate this is to start with something down‐to‐earth and rooted in our ordinary ways of thinking and talking. Once you see that even something that is seemingly straightforward has a tangle of puzzles hiding behind it, you’ll start to suspect that philosophical perplexities can arise about pretty much anything.

      1.3 Second, the metaphysics of classification will provide a nice springboard for the discussions to follow on the metaphysics of properties (in Chapter 2) and the metaphysics of parts and wholes (in Chapter 3). These parts of metaphysics are somewhat more abstract than the more down‐to‐earth things we’ll begin with here, but they are intimately related to the metaphysics of classification, as we will see later on.

1.4 Let me give you a breakdown of this chapter. In Section 1.2, I will introduce and explain a distinction between two different ways of classifying objects: an objective and a subjective way. In Section 1.3, I will discuss some cases in which it seems that we have mistakenly taken a merely subjective classification to be an objective one. But even if we sometimes do make this sort of mistake, it does seem like we still often succeed in objectively classifying objects. Section 1.4 will present an argument for the conclusion that some things do objectively belong to each other. In Section 1.5, we will explore the question of what it takes for things to objectively belong together. This will naturally lead us to a discussion of the connection between the metaphysics of classification and the metaphysics of properties in Section 1.6. (And Chapter 2 will be focused more generally on the metaphysics of properties.) Finally, in Section 1.7, we’ll close with some further questions about classification to consider.

1.2 Two Kinds of Classification

      1.5 Let’s start with something that seems easy. Think about this list of things: a cat, a dog, a kangaroo, a fish, and a loaf of bread. Suppose you were asked, “Which one of these things does not belong with the others?” I don’t think you’d have a problem answering. You’d unhesitatingly single out the loaf of bread. This wouldn’t even be a hard question for a small child. My five‐year old unhesitatingly singled out the loaf of bread too.

      1.6 Suppose we take out the loaf of bread from the list and ask again, “Which one of these things does not belong with the others?” You might struggle a bit more this time, but you’d probably exclude the fish, although that isn’t the only defensible answer. For example, you might exclude the fish because each of the remaining three is a mammal. However, you might instead exclude the kangaroo on the grounds that each of the remaining three is commonly taken as a pet. (Even in Australia, it is not very common for someone to have a pet kangaroo.)

      1.7 But suppose I gave you the following list of things: a neutron star, the number 2, the dream you had last night, and a blade of grass. Now the question “Which one of these does not belong with the others?” is much harder to answer. Why is this? I suggest that it is because any way of excluding one of these items from the list leaves us with a list of three things that don’t really belong together any more than the original four. And you recognize, at least implicitly, this fact.

1.8 But why do some groups of things belong together while other groups of things do not? A complete answer to this question requires some metaphysics: specifically, we need a theory that explains what belonging together amounts to in general. This theory will be a metaphysical theory of classification. (We’ll discuss this further in the Section 1.5.)

1.9 A classification of a group of things is just a way of breaking up that group of things into groups. Let’s say that a classification of things is a good way of classifying things when it breaks things into groups, and anything in one of those groups belongs with all the other things in that group but doesn’t belong with the things that are in a different group. Venn diagrams provide a good way of illustrating this idea.¹ Suppose we have a group of things w, x, y, and z.

      Suppose that w and x belong together and that y and z belong together, but also that no collection of exactly three of them belong together. Then a good classification would divide up our initial group of four things into two groups of two things. We could represent this classification with a picture:

      In this classification w and x have been put together and separated from y and z, and y and z have also been put together.

1.10 So far, we have kept things pretty simple. One complication is that belonging together probably comes