Today I am going to introduce one of the most fundamental and most difficult areas of philosophy, namely metaphysics. It is sometimes difficult to understand what the issues even are, in metaphysics. So Iím going to start with a fairly simple example that Iíll use to introduce the problems of metaphysics.
Imagine now that youíre in a nice bright room, and in the middle of this room there is a table, and in the middle of the table there is a big, fresh, juicy red apple. Now Iím going to ask a bunch of questions about this apple -- all of them examples of metaphysical questions. This will, hopefully, help us understand better what metaphysics is. Now donít be worried if you donít follow all of the questions that I ask. Iím throwing a bunch of them at you at once in order to give you some general impression of what metaphysical questions are like.
The apple is an excellent example of a physical object: you can pick it up, throw it around, eat it, and so on. It occupies space and time and has a variety of properties. So now suppose we ask: What does it mean to say that the apple is a physical object? In other words, what are physical objects? This might seem like the sort of question to which one canít give an answer. I mean, what could you possibly use to explain what physical objects are? But philosophers actually do try to give some general sorts of accounts of what they are. They ask: Are physical objects just bundles of their properties? Or are they substances which have those properties? Thatís called the problem of substance.
OK, hereís another sort of question. I said that the apple has properties, like being red, being big, being juicy -- those are each properties of the apple. But what does it mean to say that redness is a property? How are properties different from objects? Notice, we say that things like apples have properties like redness. But apples and redness are totally different sorts of items, of things, of entities. You can pick up and touch apples, but you canít pick up and touch redness -- well, except in the sense that you can pick up and touch red things -- like apples! So whatís the difference between objects, like apples, and properties, like redness? How can we best think about what properties are? This is something weíll talk about, called the problem of universals.
And hereís another question about what physical objects are: When in general can we say that physical objects come into being and when they cease to exist? Now surely the apple can change in lots of ways without ceasing to exist. It could get brown and rotten but it would still be that apple. But if I ate it -- well then the apple wouldnít just have changed. It would no longer exist. So there are some questions to be answered about the notions of identity, or being the same thing over time, and change.
Now this apple is supposed to exist in space (itís on the table in this room) and in time (it wasnít on the table a week ago and it wonít be on the table a week from now). But what does this talk of "space" and "time" mean? Can we say, for example, that space is like an invisible three-dimensional grid in which the apple is located? Well, suppose the apple, and every other physical object in the universe were to entirely removed from existence: then would space, that "invisible grid" still exist? Some people say not -- they say that without physical objects, space would not exist, because space is the framework in which we understand how physical objects are related to each other. So, no objects, no space.
Then there are other very different sorts of problems in metaphysics. The apple is one sort of thing; now if Iím in the room, and I say I have a mind, Iím surely going to say that my mind is a different sort of thing from the apple. I might say that my mind is immaterial, but the apple is a material object. Hereís another difference: it sounds a little strange to say that my mind is located in any particular place; maybe we could say itís somewhere in the room; but the apple is obviously located in a particular place, namely on the middle of the table. And so on. It seems clear that minds are fundamentally different from physical bodies. But if so, how can something mental, like a decision to eat, cause a physical event to occur, like biting down on the apple? How are the mind and body causally interconnected if they are two totally different sorts of things? This is called the mind-body problem, something weíll be studying in a few weeks when we study something called "the philosophy of mind." The philosophy of mind used to be, and sometimes still is, considered part of metaphysics.
OK, Iím done giving you examples of metaphysical problems. And Iíve just given you a few examples. There are many, many more problems where those came from; for example, the problem of free will and determinism has often been considered part of metaphysics.
Now, I want to say something before I try to give a definition of the word "metaphysics." Of all philosophical subjects, metaphysics is bound to look most pointless. I am sure that some of you, when you heard the questions I just asked, were asking yourselves, "What on earth is the point of even wondering about stuff like this?" So let me just remind you about what the task of philosophy is. The task of philosophy is to really get to understand the meaning and justification of our most basic beliefs. And metaphysics asks questions about the most basic of our beliefs. Metaphysics is often thought to be the most fundamental part of philosophy. If my saying that doesnít help you get over the suspicion that this is all just hifalutin nonsense, just wait. I am hoping that you will gain some personal experience of how questions in metaphysics underlie, and deeply inform, many other more obviously important questions in philosophy. So insofar as how you answer metaphysical questions makes a big difference for how you answer other obviously important questions in philosophy, metaphysical questions are themselves important.