extent than other things. Think about this list of things: me, my wife, my two daughters, and my dog Ranger. Ranger is the odd man (odd dog?) out in this list. But now consider a larger list: me, my wife, my daughters, my dog Ranger, and the number 2. Despite being even, the number 2 is the odd number out. What this shows is that although Ranger doesn’t belong in the first group as much as my daughters do, he definitely belongs in the second group much more than the number 2. So, he must belong with me, my wife, and my daughters to some extent.
1.11 What this means is that instead of focusing simply on the question of whether a specific classification is a good way of classifying, we should also consider the more general question of when a given classification is a better classification than another. We won’t have a complete theory of classification if we don’t consider this more general question.
1.12 The second complication is that there are different reasons why we judge that things belong together, and these different reasons will sometimes lead to different and apparently conflicting ways of classifying objects. But these different ways of classifying objects don’t really conflict. We already saw an illustration of this phenomenon. Let’s return to one of the lists of things that we thought about at the beginning, specifically the one that consisted of a cat, a dog, a kangaroo, and a fish. There seemed to be two equally respectable ways of breaking this list into groups. We might separate the fish from the remaining three on the grounds that the remaining three are mammals; but we may also separate the kangaroo from the remaining three on the grounds that only the remaining ones are commonly taken as pets. Is there any point in trying to decide which of these two classifications is better? Isn’t how we classify things largely dependent on what we are interested in, what we care about, what we desire, and so forth?
1.13 Sort of. There’s an important difference between the two kinds of classifications just mentioned. One of them classifies animals by looking to see whether they are related to us in some interesting social way: the classification that excludes kangaroos is based on the observations that we don’t interact with kangaroos in (some of) the ways in which we interact with dogs, cats, and fish. But it wasn’t inevitable that we don’t typically have kangaroos as pets. Imagine a possible situation in which we have kangaroos as pets instead of cats: if that possible situation had actually happened, then we probably would have felt that it was cats rather than kangaroos that do not belong on the list.
1.14 But now think about the other kind of classification, the one that excludes fish because they are not mammals. This classification isn’t based on our desires or interests, and it doesn’t classify things on the basis of how these creatures relate to us. Mammals could have existed even if no human beings had ever evolved on the planet. And mammals still would have belonged with each other in a way that cats, dogs, fish, and kangaroos do not. Moreover, we can’t easily imagine possible scenarios in which, for example, dogs fail to be mammals. We can imagine possible situations in which there are things that have the same outward physical appearance as dogs and that have similar behaviors to dogs, which aren’t themselves mammals. But that’s not the same thing as imagining a situation in which dogs aren’t mammals.
1.15 One lesson to draw from these observations is that, roughly, there can be (at least) two kinds of systems of classification. We might classify objects because we are interested in how they relate to us. We can think of these as subjective classification systems because they are driven by our interests, desires, values, and so on. But a system of classification might also classify things on a more objective basis, that is, on grounds that are independent of whether that system of classification reflects anything about how reality relates to us or what we care about. Some things objectively belong together. An objective classification system is one that classifies things together in a way that matches how they objectively belong together.
1.3 Classification Confusions
1.16 Sometimes we make mistakes about what things objectively belong together, and these mistakes are discovered only after painstaking scientific investigation. Here are some relatively straightforward examples to consider. An ordinary culinary classification might lump carrots, beets, and tomatoes into one group, while lumping oranges, apples, and grapes into another group. But from a more scientific perspective, tomatoes objectively belong more with oranges, apples, and grapes than they do carrots and beets. And as awareness of this fact has spread, how people use language to classify things has changed.2 Two hundred years ago the sentence “Tomatoes are fruits” might have seemed like a ridiculous thing to say to your average speaker of English, but that’s not the case today. Now many of us are happy to utter, “Tomatoes are fruits,” and believe that we say something true when we do. There is an interesting question of whether the word “fruit” has changed its meaning over time as a result of a greater awareness of the fact that tomatoes objectively belong more with grapes than they do with carrots. If the word has changed its meaning, then what was said two hundred years ago by “Tomatoes are not fruit” might well have been true too! But it would still have been false that tomatoes objectively belong with carrots more than they do with grapes.
1.17 A similar observation can be made about the word “fish.” Are whales fish? They used to be classified with other things that were called “fish,” but now we know that whales do not objectively belong with fish to the extent they were once thought to, and as a consequence, there is pressure not to call whales “fish.”3 One of the things that such scientific discoveries can teach us is that our beliefs about which things objectively belong together are subject to serious revision. An even more recent case is the reclassification of Pluto as not being a planet.4
1.18 Social scientists—psychologists, sociologists, anthropologists, and so on.—would be good people to consult if we wanted to know why people lump things together for subjective reasons. Maybe biology, zoology, animal psychology, and other sciences like them, might also play a role in helping us figure this out. And it will sometimes be a tough job. Occasionally the explanation for why a group of people ended up classifying some objects as belonging together can be so subtle that the people doing the classifying aren’t even aware of these reasons. And when this happens, sometimes people falsely believe that the things that they have subjectively lumped together really objectively belong together. As we will see in a moment, at times this can also affect how people classify each other.
1.19 Consider, for example, the practice of classifying persons on the basis of race. Many scientists believe that racial classifications are not backed up by the biological facts.5 Consider, for example, how a parent classified as belonging to one race can have a child classified as belonging to another race. The parent and child will likely have more biologically in common with each other than they would with other members of “the same race.” But as any student of the history of racism is aware, people discriminated on the basis of race because they thought that “racial classifications” grouped people into collections that objectively belonged together.6
1.20 If this is correct, then racial classifications are very subjective in the sense described earlier: racial classifications are based on contingent features of societies rather than on genuinely important objective features of the world. This seems to be a view that most people who accept the idea that race is socially constructed accept, though many augment this basic position with other philosophical theses.
1.21 Some philosophers have argued for an even stronger conclusion: there are no races. This is the position defended by the philosophers Kwame Anthony Appiah and Naomi Zack, among others.7 We’ll call this position race eliminativism. Here are the basic ideas behind race eliminativism: not all attempts at