In today’s lecture, we imagined there might be an “H virus” that’s very infectious and gives people the “hiccup disease.” (Should it be spelled “hiccough”?) We considered three different claims people might make:
I have the hiccup disease because my test came back positive. (Imagine someone starts off thinking they either have the hiccup disease or they have indigestion. Then they come and say this to you.)
I have the hiccup disease because I went to my friend’s birthday party, and some people there had it.
I have the hiccup disease because the H virus is in my body, and it overwhelmed my immune system.
We spent some time talking about what the difference between these claims might amount to. One thought was that the first claim would be better if it started “I know I have the hiccup disease because …” Other observations made about the first claim is that it has to do with what kinds of evidence or knowledge we could have about the disease. (Maybe the other claims bear on that too; but the first claim only seems to bear on that.)
The second and third kind of claim seem to be different. We’re going to think now about what makes them different from each other. The second claim, some of you suggested, has to do with the cause or origin of the disease. Whereas the third claim seems to be more about what it is to have the disease. Someone said that the third claim talks about something that has more of a foolproof or guaranteed link to the disease. Whereas the second claim, on the other hand, talks about something that might tend to lead to the disease, but isn’t guaranteed to do so. (Even if in fact you contracted the disease, and were at your friend’s party, it might possibly be that you picked it up somewhere else.)
I said that philosophers will talk about the kind of connection illustrated by the second claim as a causal dependence. Whereas the kind of connection illustrated by the third claim, they’ll describe using language like this:
- this describes what it is to have the disease, or what the disease consists in
- having the H virus in your body overwhelming your immune system constitutes having the disease
- you have the disease in virtue of having the H virus in your body overwhelming your immune system
- the link between the disease and the virus is a metaphysical dependence, not merely a causal one
I tried to give some other examples of this kind of relationship, by suggesting that striking a match only causes the match to light, but being enrolled at UNC Chapel Hill constitutes one way of being a college student. Perhaps this example is too simplistic; I’m assuming that UNC Chapel Hill is essentially a college; and that could be disputed. But I hope the idea we’re illustrating here is intuitive enough. The idea was that being a college student isn’t some further, optional extra to being enrolled at UNC Chapel Hill. Once you’re enrolled at UNC Chapel Hill, you’re then automatically and already a college student.
One important feature of the “college student” example was supposed to be that there are multiple ways of being a college student. Maybe being enrolled at UNC Chapel Hill makes you a college student, in some closer-than-merely-causal sense, but being enrolled at NC State can also make someone a college student. So being a college student isn’t the same thing as being enrolled at UNC Chapel Hill. Here we wouldn’t want to say that “being a college student consists in being enrolled at UNC Chapel Hill,” because that implies that it’s the only way to be a college student. But it would be OK to say “This person is a college student in virtue of being enrolled at UNC Chapel Hill.” Other people could be college students in virtue of being enrolled elsewhere.
Another example of merely causing: throwing a ball against a window makes/causes the window to break.
Another example of more-than-merely-causing: the relation between some piece of software and the physical states of the computer it’s running on. There are certain electrical changes going on in my computer. Also my computer is running a Solitaire game. But the running of Solitaire is nothing over and above those electrical changes. Their taking place doesn’t cause my computer to run Solitaire, in the way the ball caused my window to break. Rather, their taking place is what it is for my computer to be running Solitaire. It would be impossible for my computer to go through those changes and for Solitaire not to be running.
It wouldn’t be impossible, on the other hand, for you to throw the ball against the window and the window fail to break. In principle, it’s possible that the window might fail to break. It may even be physically possible (for example, if someone installed special dampers on the window). But it would certainly be metaphysically possible for the ball to hit the window, and to bounce away harmlessly. So this is an important difference.
Let’s introduce a new piece of technical vocabulary to help capture this difference.
We say that one set of facts supervenes on another more basic set of facts when the more basic facts somehow “fix” or “determine” that the first set of facts has to be true. That is, when it’s metaphysically impossible to have the basic facts settled in a certain way without also having the other set of facts settled, too. In our example, whether you’re a college student supervenes on what institutions you’re enrolled at. I was supposing it’s metaphysically impossible to be enrolled at UNC Chapel Hill but fail to be a college student. (I’m assuming for this example that our school couldn’t cease to be a college — it couldn’t, for example, turn into a music conservatory or a trade school — and still be UNC Chapel Hill.) And if you and your friend Teresa are both enrolled at the same institutions, then either you’re both college students or neither is.
Similarly, whether my computer is running Solitaire supervenes on what electrical patterns are there inside the computer. If I’m running Solitaire, and your computer has exactly the same electrical patterns, then your computer must also be running Solitaire. It’s metaphysically impossible for it to have those patterns but not be running Solitaire.
Here’s another example. Some people claim that the beauty or aesthetic value of a painting supervenes on the facts about how the paint is distributed on the canvas. This means that once you’ve distributed the paint on the canvas in a certain way, you’ve thereby fixed how graceful the painting is, whether it’s beautiful or not, and so on. Any painting which has its paint distributed in exactly the same way would have to be equally graceful and beautiful. It’s metaphysically impossible for there to be two paintings that are the same in how their paint is distributed, but different in respect of how graceful/beautiful they are.
- I’m not saying that this is the correct view about paintings. Some people argue that forgeries are less beautiful than original paintings — even if they have their paint distributed in exactly the same way. That is a controversial question. But regardless of whether it’s a correct view that any two paintings with the same distribution of paint have to be equally beautiful, thinking about this view helps us to understand how the term “supervenience” works. We see that another way to express the view is to say: the beauty of the painting supervenes on how the paint is distributed on the canvas.
Note that when A supervenes on B, it does not follow that B supervenes on A. There might be two paintings of equal beauty which nonetheless have their paint distributed differently on the canvas. That shows that it’s sometimes possible to change how the paint is distributed, while leaving the painting just as beautiful as it was before. The claim that the painting’s beauty supervenes on the distribution of paint is compatible with that. It only implies that the reverse sort of change is impossible. If the beauty is fixed by the distribution of paint, then you can’t change how beautiful the painting is while leaving the distribution of paint exactly the same.
Recall that the dualist and the materialist disagree about whether our mental properties are “independent of” how we’re built physically, or whether the way we are physically put together “wholly determines” what mental properties we have.
Let’s look more closely at this disagreement. What does the dualist mean when he says that your mental properties are “independent of” your physical properties?
The dualist thinks there is some independent realm of mental substances, and mental facts. But most materialists think that the mental facts are “nothing over and above” the physical facts. We can understand what the materialist is saying here in this way: he thinks that all the mental facts about you supervene on all of the physical facts about you. In other words, there could not possibly be someone who is physically just the same as you, without his also being mentally just the same.
In fact, this is a more restricted kind of “materialism” than we were considering before. Some philosophers reject substance dualism: they think that the only substances there are are physical ones. But they think there are two independent kinds of properties: physical properties and mental ones. They think that the mental properties can’t be reduced to any physical properties, and they think they don’t supervene on the physical properties either. So on their view, there could be people who were physically perfect copies of each other, but whose mental lives were different. Philosophers who think this are called “property dualists.” You may come across some discussion of them. But we’re going to focus in this class on the debate between the substance dualists, on the one hand, and the materialists who accept the more restricted kind of materialism, on the other. These materialists think not only that there are only physical substances; they also think that the physical facts fix or metaphysically determine all the mental facts (and every other relevant kind of fact, too). On their view, everything supervenes on the physical facts.
The dualists might allow that your physical properties typically cause you to be in given mental states. If I hit you on the head, that will typically cause you to have a headache. But, on the dualist’s view, there is nothing metaphysically impossible about there being someone who is just like you physically, but who has different mental properties than you, or perhaps no mental properties at all.
So our materialist thinks that the mental facts supervene on the physical facts: it’s metaphysically impossible for two things to be exactly the same, physically, but to differ mentally. The dualist, on the other hand, thinks that it would be metaphysically possible for there to be someone just like you physically but who had a different mental life than you have (or no mental life at all).