THE NATURE OF THINGS: An Introduction to Metaphysics for Scientific Thinkers Barbara Ellen Hannan 12200 Academy Road NE, #712 Albuquerque, NM 87111 [email protected] [email protected] 505-­‐440-­‐4437 (cell) In memory of my father, William Seaton Hannan, Jr. 1922 – 2009 …inasmuch as the calling of the miner excels in honor and dignity that of the merchant trading for lucre, while it is not less noble and far more profitable than agriculture, who can fail to realize that mining is a calling of peculiar dignity? Georgius Agricola, De Re Metallica 2 “The time has come,” the Walrus said, “To talk of many things: Of shoes -­‐-­‐-­‐ and ships -­‐-­‐-­‐ and sealing wax -­‐-­‐-­‐ Of cabbages -­‐-­‐-­‐ and kings -­‐-­‐-­‐ And why the sea is boiling hot -­‐-­‐-­‐ And whether pigs have wings.” Lewis Carroll 3 INTRODUCTION: Metaphysics: A Labyrinth With Many Doors What Is Metaphysics? A certain set of problems concerning existence (or reality, or the nature of things) has come to be called ‘metaphysics’ among philosophers. These problems are all curiously interconnected. If you start thinking seriously about any one of them, you will soon find yourself thinking about most, or all, of the others. These questions are so fundamental and so annoying that many people do not want to think about them seriously. Thinking about metaphysics is so difficult as to be painful -­‐-­‐-­‐ at least for most people. Despite its difficulty, metaphysics is worthwhile. Metaphysical questions are at the heart of everything interesting, including mathematics, logic, science…even ethics and theology. Metaphysical Stream of Consciousness Our judgments about things may be expressed in declarative sentences. Some declarative sentences are true, and others false. True sentences are about things and their properties. What kinds of things must exist in order to make all of our true sentences true? What is the relation that holds between a true judgment or a true sentence and the objective world of facts and things? 4 How can a thing change over time and yet remain the same thing? If it changed either its parts or its properties, it’s not the same. Yet, we talk all the time about persons and other objects changing over time, yet remaining the same things that they were before. What is a thing? Which of the things we call ‘things’ are really things, with some kind of genuine unity, and which are just accidental conglomerations of things? Are there any simple things (things that are not made up of other things)? What is the relation that holds between a thing and its properties? How can things come into existence? It seems that whatever exists had to come to be out of something that was already there. Nothing comes from a void, from the complete absence of anything. It seems there must be something that has always existed, that cannot not-­‐exist. But what kind of thing is that? How can things go out of existence? A complex thing can go out of existence by being taken apart. Matter can cease to exist by being converted into energy. However, when something ceases to exist, it does not become nothing. What is time? What is change? If nothing changed, would time pass? Does time really pass? Time seems to flow, like a river. It seems as if the present is all that really exists . The past is over and gone, and the future isn’t here yet. But when is the present? As soon as you try to refer to it, it’s over and gone, into the past. Perhaps the “flowing” of time is just a metaphor. Well-­‐confirmed theories in modern physics suggest that spacetime is the fabric of physical reality; time is just another dimension in which we exist, 5 analogous to familiar spatial dimensions. If that is true, then it seems we should be able to go backward and forward in time, just like we can go backward and forward in space. Is the past “still there,” so we might go “back” in time and visit it? Is the future “already there,” so we might go “forward” in time and visit it? Suppose you went back in time, found yourself as a child, and killed that child. But then, you never would have grown up to become the person who went back in time and killed your younger self. Besides, how could you kill your childhood self? At the time of the shooting, you would have to be two different people (so that one could shoot the other), and also one and the same person existing simultaneously in two different time-­‐streams. Does that even make sense? Suppose the future is “already there.” This implies that sentences about the future have truth-­‐values (that is, they are true or false), already, right now. This implies that facts about the future are already set, and that there is nothing we can do now to change the future. But such fatalism conflicts with our ordinary, nearly unshakeable belief that we have free will. We must assume, for practical purposes, that we can choose to do things that will make our futures better than they might otherwise be. Science, however, theorizes that we persons are complex physical objects (organisms), and that our thoughts and feelings are electrochemical states of our brains. If thoughts are physical states of our brains, then their content (what they mean) is somehow encoded or represented physically. How could electrochemical states have content or meaning? What is meaning? 6 If science is correct, then our brain-­‐states are caused to be as they are by prior physical states and events. This causal chain goes all the way back to when we were fetuses…and still further back, all the way to the Big Bang (if there was a Big Bang.) So, whether you have rational thoughts and compassionate feelings that lead you to do good things, or you have evil thoughts and anti-­‐social feelings that lead you to do bad things, none of that is up to you; you are not responsible. Science seems to imply that our practice of holding ourselves and each other responsible for our actions is a relic of an outmoded worldview. The death of responsibility is hard to accept. We all feel that we are responsible for our own actions, when no legitimate excusing condition (such as a non-­‐culpable mistake of fact, being forced to do something against your will, or a mental illness that interferes with your normal rational capacities) applies. It seems morally suspect, a kind of Sartrean “bad faith,” to pretend otherwise. We all feel that it is up to us whether we will waste our lives (in self-­‐pity, drug abuse, laziness, or whatever), or use our opportunities productively and make the most of our talents and abilities. Certainly, the best people are those who take responsibility for their own lives. It would not be possible to live a morally decent human life without taking oneself to be responsible for one’s own rational choices and deliberate actions, and even, to some extent, for one’s own moral character…would it? Is it possible for us to keep our normal moral (and legal) practices involving responsibility, while accepting science’s verdict that we are nothing but complex blobs of matter, subject to causation? Is the moral worldview compatible with the 7 scientific worldview? If so, how? If not, what then? Can we live with our beliefs split into two incompatible halves, the theoretical and the practical? When we talk about morality, what in the world are we talking about? Could science be mistaken in the assumption that we are just complex blobs of matter (“ugly bags of mostly water,” to quote an episode of Star Trek: The Next Generation)? Perhaps we are souls or spirits, immaterial substances. If we were, would that enable us to escape the causal nexus and be genuinely free and responsible? How? Would it enable us to survive the deaths of our bodies? How would immaterial souls recognize each other and communicate with each other? How could a state of an immaterial substance have content or meaning? Again, what is meaning? If there are souls or spirits, what kinds of animals have them? How does the soul or spirit interact with the physical body? If dogs and horses and parrots have souls, does an amoeba? We do not hold dogs or horses or parrots morally responsible for their actions, much less amoebae. Why not? What’s the difference between persons and other living things? Could there, perhaps, be no physical stuff, no matter, at all? Could the entire physical world be merely a phenomenal world that exists only for minds or souls? What about space and time? If matter is merely phenomenal, then it seems that the space in which material things seem to exist must be merely phenomenal, too. Ditto for causal connections among things. But what about time? Even souls, it seems, must exist in time. Once again: what is time? 8 Putting aside the distressing (or comforting?) possibility that the whole physical world is merely phenomenal, what is causation? Which things and events are genuinely causally connected with each other? Could there be two kinds of causation, causation by physical events, and causation by rational agents, with only the former subject to laws of nature? How do causes bring about their effects? Is the process deterministic, or merely probabilistic? What is a law of nature? Science tells us that the physical world is characterized by regularities that ensure predictability. These regularities are learned through experience, and they seem to reveal an objective causal order. Events cannot violate the laws of nature. But why not? It would involve no logical contradiction for events to violate the rules we now take to be laws of nature. It seems like the laws of nature could have been different than they are. In other words, they are contingent; they are not logically necessary. So, when we say “Events cannot violate the laws of nature,” what kind of “cannot,” what kind of impossibility, are we talking about? Some necessarily true sentences are true, it seems, just because of the way human beings have decided to carve up the world and divide things into classes. A bachelor is an unmarried male because we care about who is married and who isn’t, and we decided to call unmarried males ‘bachelors.’ This has no deep metaphysical significance. Other necessarily true sentences are true because of the very nature of things, independently of human decisions and interests. Tortoises are reptiles. 9 Silver is a metal. We didn’t make up classifications like ‘reptile’ and ‘metal.’ We found them in the natural world. They represent natural kinds. Which kinds are the natural kinds? Do natural kinds have essences? Is there some property shared by all the members of a natural class that makes them what they are? Do I have an essence? What makes me, me? What kinds of things about me could be different, and which could not be different without making me another person? Could my essence possibly survive the death of my body, or inhabit a body different from the body I call my own? A Labyrinth With Many Doors My metaphysical stream of consciousness, just related, begins with reflection on language, logic, meaning, and truth. This is one of many entryways into the nexus of metaphysical problems. It is often the way philosophers get into metaphysics, since many philosophers (especially in recent times) study language, along with formal logic. (During the first week of my Symbolic Logic class, I have to explain to my students the difference between a sentence that is contingently true and a sentence that is necessarily true. There I am, suddenly, in the thicket of metaphysics!) Another doorway into metaphysics is science. Metaphysical questions lurk both at the heart of science, and around the periphery of science. No reflective scientist can avoid running into them. 10 What separates metaphysical questions from scientific questions is the generality and abstractness of the former. A chemist might study how an acid and a base combine to form a salt. A biologist might study how an egg cell and a sperm cell combine to form a zygote, and how the zygote in turn transforms into an embryo and eventually into an adult organism. The metaphysical question involved in both processes is how can things change into other things? This is a difficult question, but not a meaningless one. (Some scientists, due to the unfortunate legacy of a misguided philosophy of science called ‘logical positivism,’ dismiss metaphysics as meaningless. This is a mistake. It amounts to “throwing out the baby with the bathwater,” since science is inescapably intertwined with metaphysics.) Many metaphysical problems arise from apparent conflicts between the way things seem to reflective common sense, and the way science tells us things really are. Twentieth century philosopher Wilfrid Sellars (1912 – 1989) put it this way: there is a “manifest image,” a way the world seems, to common sense, to be. But then science comes along. Eventually, a scientific worldview comes about, the “scientific image.” The experts, the scientists, tell us how things really are. As human beings living in the scientific age, we are challenged to keep adjusting our “manifest image” in order to keep it consistent with the “scientific image.” It is not clear, however, that this can always be done. This creates cognitive dissonance that can be repressed only for so long. For example: in order to live as responsible human beings, we must assume that we make free choices, guided by reason. Science explains all phenomena, 11 including human actions, in causal terms that seem incompatible with rational agency. This kind of problem -­‐-­‐-­‐ where science tells us P, but we continue to live as if not-­‐P -­‐-­‐-­‐ has become central to what philosophers now call ‘metaphysics.’ The “scientific image” has become increasingly bizarre and difficult to grasp as science has progressed in recent times. With the advent of indeterministic quantum theory in physics, it often seems as if science itself has stopped making sense. How can a sub-­‐atomic particle/wave be in two incompatible states at one and the same time? Yet, this is what the mathematics of quantum theory seems to suggest. Erwin Schrödinger (1887 – 1961) expressed the relevant kind of cognitive dissonance with his famous thought-­‐experiment about the cat in the box, alive and dead at the same time. How can the entire universe have emerged from a quantum vacuum in a Big Bang? A quantum vacuum is not a void (though physicists sometimes confusingly call it “nothing”) but still we wonder how so much could have exploded out of so little. When we wonder about the implications of our current scientific theories, we are doing metaphysics. This is perhaps the point at which metaphysics most clearly overlaps with science, since reflective scientists cannot resist indulging in such speculative interpretation. Some people get into metaphysics through the door of religion. Many of us are raised in religious traditions, and taught that certain claims are true: that God 12 exists and that human beings have immortal souls, for example. It is through our religious education that many of us receive our moral framework -­‐-­‐-­‐ what we consider to be right and wrong. But we start to wonder if God really exists, if the notion of an immortal soul makes sense, if morality has any necessary connection with God, and so forth. These are metaphysical questions. Our capacity to reflect on the human condition is another door into metaphysics. Human life is short, it contains suffering, and it ends in death. We find ourselves wondering what we are, why we must suffer, and what death is. When those we love die (and this includes both people and beloved pets) we cannot help but wonder if we might somehow be re-­‐united with them, when we ourselves die. These, too, are metaphysical questions. 13 CHAPTER ONE Things Things, Time, and Change Have you ever asked yourself what makes one object different from another? How is reality actually carved up into “this” and “that”? We distinguish the mountain from the plain, the rock from the pond, the tree from its leaves, the sky from the clouds; but are these boundaries perhaps artificial, based merely on human perceptions, needs, and concerns? Where does one “thing” end, and another “thing” begin? Suppose I ask myself, “How many things are in this room?” It takes only a little reflection to suspect that there is no definitive answer. Any candidate for an answer will depend, it seems, on some prior decision as to what you are counting. Obvious candidates for things turn out to have parts that are also things. The parts of things in turn have other parts, even if the parts are very closely stuck together. A book is a thing; but so is a page of a book. A coffee cup is a thing, but so is the handle attached to the coffee cup. Pages and coffee cup handles are, we are told, make of invisible molecules and atoms, which are also things. Whether sub-­‐
atomic particles are things is debatable (because of phenomena such as “entanglement,” we possess no clear criteria of sameness and individuation for them) but still current science tells that even atoms are made up of something more basic. 14 Two of the occupants of this room (myself and my parrot) are living organisms. Are we living organisms genuine things, naturally unified in a way that books and coffee cups are not? Some philosophers have thought so. Aristotle (384 – 347 BCE), for example, taught that a living organism is one thing because its parts (organs, tissues, etc.) exist only relative to the life-­‐functions of the whole. You can’t just take a stomach, a liver, a skin, etc., and stick them together, and produce a living organism. Stomachs, livers, and skins, detached from whole, living organisms, or as parts of dead bodies, are not really stomachs, livers, and skins any more. They might still have the right shape, but they no longer have the right nature or function. In a living organism, the parts depend on the whole, whereas in artifacts and other non-­‐living complexes, the whole depends on the parts. This gives an organism substantial unity in Aristotelean terms. Gottfried Leibniz (1646 – 1716) had a similar insight when he noted that perception and appetition are activities of one, unified entity. There must be an “I” that perceives and acts. Leibniz concluded that minds or souls are the “monads,” the one-­‐things, the things that are genuine things. A better-­‐known metaphysical reduction program, one that guided most of the history of science, sought material atoms as the simple things from which all complex things are composed. The atomist reduction program ultimately failed. We now take “atoms” to be made of quantum fields -­‐-­‐-­‐ mysterious, un-­‐thing-­‐like things. 15 Change and Identity (Sameness) of Things Things change. How can a thing change, yet still be the same thing? This is the problem of change, a traditional metaphysical puzzle. One aspect of the problem of change concerns identity. Strict identity is defined as follows: if a is identical with b, then a and b have all and only the same parts and properties. However, we speak as if one and the same x continues to exist at different times, possessing different parts and/or different properties at those times. For example, my parrot is the same parrot I purchased from an aviary several years ago. But she is bigger and heavier now than she was then; she has different feathers, having gone through several moults; and so forth. Living organisms change their cells constantly as they move through time. For another example, my car is the same car it was last week. But I just had the oil and oil filter, and the air filter, replaced. I also replaced a hubcap that went missing. How many of my car’s parts would have to be replaced before I stopped saying it was the same car? If x-­‐at-­‐time-­‐one has different properties, and/or different parts, than x-­‐at-­‐
time-­‐two, they aren’t really the same x -­‐-­‐-­‐ at least, not in the sense of strict identity. Yet, we talk as if they were. It seems that, in everyday speech, we use “same x” in such a way that we don’t mean strict identity; we mean something much more vague, involving degrees of continuity and similarity. Our ordinary concept of an object is intrinsically vague. 16 Basic Ontological Categories Could the entire “manifest image” be false? Could the progress of science entirely re-­‐write our conceptual scheme, so that nothing at all remains of our pre-­‐
scientific worldview? Many scientifically inclined people tend to answer this question with a gleeful, “Yes! Go where science leads us, though the heavens fall!” Perhaps, though, a bit of caution is warranted. Perhaps there are pre-­‐
scientific ways of classifying that are so basic it would be incoherent to suppose that science could eliminate them. Science itself would presuppose them. These are what metaphysicians have sought when attempting to list basic ontological categories. This project began with Aristotle. In the book called Categories, Aristotle suggests that we may examine the structure of language, and find the basis for a fundamental classification of the things that there are. The most basic category is that of substance (ousia), an independently existing entity, one of the fundamental ingredients of reality. Everything else that exists (properties, for instance) depends for its existence on the existence of substances. Aristotle suggests that we begin our ontological investigation with language not because language somehow determines what there is, but because language is a tool for communicating with each other about reality. It seems reasonable to suppose that linguistic universals (for example, there are subjects and predicates, nouns and verbs, in all languages) correspond to basic divisions in reality. 17 Otherwise, we could not succeed in communicating with each other about the common world we all inhabit. This is not to say that we can simply “read off” the structure of reality from the surface structures of sentences in natural languages such as Greek or English. It isn’t that simple. We can say, truly, that a person wore a broad grin, or that a person did something for the sake of love. This does not mean that grins and sakes are genuine objects. English has a way of noun-­‐izing abstractions that are not really objects. Lewis Carroll liked to make jokes based on this feature of English syntax. (Remember the Cheshire Cat’s grin?) That there are objects, however, seems a reasonable metaphysical claim. How could we think or talk, without things to think or talk about? In Box One below, I make a first stab at a list of fundamental ontological categories. The listed categories concern being and its modes. These categories form a group of interdefined notions. Attempt to define any one of them, and you will find yourself using some of the others. Arguably, such concepts are ineliminable because we can’t even meaningfully talk about what might exist without them. Box One: Some Basic Ontological Categories Object, Substance, Event, Property, Force or Power, Cause, Relation, State of Affairs, Fact, Individual, Kind, Part, Whole, Time, Space, Existence, Identity, Similarity, Possibility, Necessity, Contingency. 18 19