To make the transition to Einstein’s universe, the whole conceptual web whose strands are space, time, matter, force, and so on, had to be shifted and laid down again on nature whole.
—Thomas Kuhn
One problem metaphysicians have been dealing with for, well, forever, is the unfortunately necessary intertwining of metaphysics and epistemology. Metaphysics is the philosophical study of what exists; epistemology is the philosophical study of knowledge. And it’s trivial to point out that the best we can do in detailing what there is that exists is to rely on our best epistemology: We can’t talk about what we know about, without talking about what (and how) we know. If we know about quarks, it’s not simply the case that quarks exist, but that we figured out that they exist. Our catalogue of items in the universe is inherently tied to our knowledge of those items.
Why is this problematic? Well, many metaphysicians are very conscious and conscientious about keeping existence separate from knowledge of existence. Much of the problem can be traced back to the venerable Bishop Berkeley, who posited that everything in the universe in actually mind-dependent for its very existence — it’s not, Berkeley thought, just that the computer screen in front of you is merely hidden from view when you close your eyes, but that this lack of observation actually means the computer screen is not really there when your eyes are closed. Problems with this theory forced Berkeley to say that God observes everything at all times, and so there’s no worry about things blinking in and out of existence with the blink of an eye. God never blinks. But regardless of the absurdity of this centuries-old bit of philosophy, the aftershocks have stayed with us. There’s something very compelling, apparently, about the idea that our minds have metaphysical power — that minds can create some of reality.
The great irony is that the best scientifically-minded philosophers of the 20th Century, while trying to shore up the mind-independence of the external world, actually gave proponents of mind-dependence a strong foothold in the metaphysical debate.
Naturalized epistemology — the brain child of W.V.O. Quine, though it was clearly anticipated hundreds of years earlier by David Hume — takes science to be the paragon of knowledge-farming; the discipline whose results we are most certain about. Naturalism, though, if we accept it, forces us also to acknowledge the following: We can’t make judgements about the world from some point of privileged access outside of science. That is, there is no way to step outside science and see what there is in the world; we don’t get a clearer picture of quarks without science — science itself tells us about quarks, and without science this piece of ontological furniture would not be accessible to us whatsoever. Our metaphysical house, chock full of interesting furniture, wouldn’t merely look somewhat different without science; it would be a bare, dirt-floored cabin with very little of interest in it.
This leads to a very tantalizing point. Science often changes its mind, and in such episodes of change what we take to be our ontology (our catalogue of things that exist) changes as well. For instance, once upon a time science told us that there was a substance called phlogiston that is released from things when they are burned. This substance — a consequence of a good scientific theory that explained several phenomena related to chemistry — was taken by scientists (and the informed public) as existing in the world. If science is our best arbiter of what exists, then, at the time during which science told us that phlogiston existed, there’s a strong sense in which it actually existed. Science, remember, tells us what there is, and there’s not privileged perspective outside of science to figure out our metaphysics. It turned out, however, that the phlogiston theory of chemistry ran into serious problems, and was more or less wholesale replaced by the oxygen theory of Lavoisier. In this new theory, there was no place for phlogiston. At this point, science told us that phlogiston does not exist.
There are (at least) two conclusions that can be drawn from this, each of which I will encapsulate using the Kuhnian metaphor at the top of this entry:
Standard Naturalism: The whole of science forms a conceptual web from which vantage point we purvey the world. There is no spot outside of the web from which to purvey the world. We can change science by changing some part of the web — this amounts to changing our ideas about an unchanging world. The world is independent of our ideas about it, even as we discover new ways to look at what exactly is in it. For instance, we were simply wrong about the existence of phlogiston. It never existed.
Kuhnian Mutant Naturalism: A scientific theory is a conceptual web that uniquely lays upon the world giving it its shape. When a new theory is developed, an entirely new web is made. There is still no place outside of the web from which to purvey the world, but we can shuck off the entire web in favor of a new one. The world is partly dependent for its existence on our ideas about it — whichever web we throw onto the world actually gives the world its shape. When we change our ideas, we change the world. For instance, phlogiston actually did exist while scientists were working with phlogiston theory. When Lavoisier came up with a new chemical theory, the world actually changed — phlogiston disappeared, and in its place oxygen and other items filled our metaphysical cupboards.
Many have noted from Kuhn’s version of naturalism that he is an anti-realist in the Kantian vein. We won’t get into the thickets of Kantian metaphysics here, but, in short, he believes that our ideas are not merely a pre-condition for theorizing about things, but that theorizing indeed is a pre-condition for the very existence of things. Contrary to this, standard naturalism usually goes hand in hand with common-sense and scientific realism, wherein, as Philip Kitcher notes: “Trivially, there are just the entities there are. When we succeed in talking about anything at all, these entities are the things we talk about, even though our ways of talking about them may be radically different.”
One reason Kuhn is led to his odd metaphysics is because of his implicit description theory of reference. On a description theory, the only way to correctly refer to an entity is to have its unique description in mind; but if a scientific revolution changes the description associated with a key scientific term, then the old description no longer refers. This leads Kuhn to the idea that competing scientific paradigms are incommensurable. It also motivates his metaphysics. If a term once referred and now it does not, all on the basis of our changing descriptions, then by some inferential jump one could think that this correlation was causal; i.e., that our changing descriptive thoughts cause a change in the world.
We’ll examine description theories and the philosophy of language in an upcoming post. Stay tuned…