Main points
Hume maintains that there are two “objects of human reason”, relations of ideas and matters of fact.
What we know by reasoning about the relations among our ideas is certain, its denial is contradictory and inconceivable. This kind of knowledge does not depend on the relationship between our ideas and objects.
What we know by reasoning about matters of fact, by contrast, is not certain and does depend on the relationship between our ideas and objects. Hume argues that reasoning about matters of fact always involves finding cause and effect relations among objects.
“Reasoning” is thus only one way that we can know matters of fact: I can know matters of fact by seeing or remembering them, for instance. Neither counts as reasoning, as Hume understands it, since reasoning involves knowing something through a process of thought as opposed to seeing or remembering it.
So what of these cause and effect relationships? How do we infer what effects will follow when we see a particular cause? For instance, I see the cue ball moving towards the 8 ball and know that the 8 ball will move along a particular path. How? Or, conversely, how do we infer what must have taken place to have brought about an observed effect? I see that the classroom is clean and tidy and conclude that someone must have cleaned and tidied it. How do I do that?
Hume argues that I have no reason for drawing either conclusion. I could not arrive at the conclusions through a demonstration, a process involving successive comparisons of ideas, because it isn’t contradictory to suppose that the 8 ball will not move or to suppose that a mild earthquake rearranged the chairs and shook the dust off of the board.
Really, no one thinks that it works like that. We think that we draw these inferences on the basis of past experience of billiard balls and cleaning. Billiard balls move in regular ways and only human beings tidy rooms.
But Hume has an argument that seems to show that this doesn’t give us a reason to draw our conclusions either. There is no way of showing that we can draw inferences about unobserved effects or causes based on what has been observed. Attempting to explain why this is an appropriate kind of reasoning involve moving in a circle.
Or so Hume maintains.
What is conceivable?
We encountered a common difficulty at several points in the discussion. How can Hume prove that something is or is not conceivable?
For instance, on Wednesday, Tom maintained both that certain changes in the physical world are inconceivable and that changes in the numerical world are conceivable. Barrett picked up the thread on Friday, insisting that you couldn’t really conceive of radical changes in the physical world, such that the 8 ball wouldn’t move at least a little.
Leaving aside the specific cases, there’s a methodological issue here. How do you go about arguing about what is or is not conceivable?
One thing you can do is present cases and ask the other party to the discussion to think seriously about them. Another thing you can do is to specify very precisely the inference being made. If it’s “one ball’s striking another will cause the second to roll in the same direction”, then the magnetic marbles can be brought out to show that this isn’t certain. And that’s what both sides did.
But if each side digs in its heels, and words its inferences very carefully, I don’t know if there’s any way of showing that one or the other must be mistaken.
I don’t know if that’s a weakness in Hume’s approach or a limitation that we have to acknowledge in our ability to prove points in this area.
Two conceptions of science
I think there are two ideas about what science does that were at play in our discussion. I myself believe both of them, even though I concede that they cannot both be correct. That’s a philosophical problem!
The one idea is that scientific laws are just generalizations based on past experience. They don’t expose the “secret causes” or tell us why a cause brings about an effect. They just sum up, in mathematical form, what we have observed about the interaction of causes and effects.
The other idea is that scientific laws capture the fundamental nature of reality and do explain why causes bring about effects. When we achieve perfect statements of the laws of nature, we will understand exactly why everything had to happen as it did.
Hume obviously upholds the first view. If you think a bit about what would follow from Descartes’s view that the essence of body is extension, you can see how he would support the second. Bodies, according to Descartes, are geometric shapes. You can characterize them completely in terms of their geometrical properties: lines, angles, curves, and the like. Physics is very complicated geometry. But it is geometry and so its laws are just as certain the conclusions of geometrical proofs and constructions.
Religious background
Of course, it’s not so easy to get geometrical shapes to move or to explain how one shape causes things to happen to another shape. For that, Descartes had God. He held that God is the source of all motion in the physical world.
This is the doctrine that Hume referred to in §7, paragraphs 21-25. It’s called “occasionalism”. Here’s why the name makes sense. According to this doctrine, the physical event of one billiard ball’s hitting another is the occasion for God to move the second ball. It was a familiar idea at the time. I’ll go into that a bit on Wednesday, when we talk about section 7.
There’s something else about the religious background to Hume’s discussion of causation that I should mention. Remember how he started off with an example involving Adam? Look at Section 4, paragraph 6. Hume argues that Adam, the first man in the Christian tradition, knew about cause and effect relations only through experience. He couldn’t tell from knowing what water is that it would not support his weight if he tried to walk on it. He had to find that out for himself.
There’s something significant about his choice of Adam. The book of Genesis [pdf] tells us that Adam was made in God’s image (Genesis 1.26). This was understood to mean that Adam’s knowledge of the world was like God’s. For instance, Adam was thought to have the ability to understand the fundamental nature of things; that’s how he was able to name everything (Genesis 2.19-20). Perfect knowledge of the essence of things was thought to give him the ability to understand why things have to happen, why the essential nature of things would lead to changes as they interacted with one another. In short, he had certain, perfect knowledge of the world, as it was, is, and will be, just as God does. To get the feel for this kind of view, look at a two page snippet from Robert South’s sermon [pdf] in 1662.
Of course, Adam was expelled from the garden of Eden; this is what Christians call “the Fall”. One consequence of the Fall was that Adam and his descendants lost the power of perfect knowledge. That, according to the prevailing view at Hume’s time, was a consequence of Adam’s fall that we have to live with. But we are still all made in the image of God and so we still all retain something of this ability to understand the world.
We retain it insofar as we are like God and we are like God insofar as we are rational. If we could just perfect our rational nature and get past the sources of irrationality in us, we could regain the kind of knowledge that Adam had. That was how philosophers and, to an extent, scientists, understood what they were trying to do in the seventeenth and eighteenth centuries. They were trying to recapture Adam’s lost powers.
Hume, on the other hand, sought to deny the whole picture of human nature. We aren’t rational beings and, if we tried to be, we would be completely helpless. We could not draw the causal inferences that we need to draw in order to survive, we would not have moral knowledge, and we would not do anything at all. That’s the theme of Hume’s philosophy, of which we are reading only a small part.
What happened to this story about Adam’s being made in the image of God? It’s alive and well. Here’s a bit from the New York Times, October 2, 2005.
As the debate over whether intelligent design should be taught in schools continues, New Man, a Christian magazine for “men on a mission,” makes the case for a literal Adam in its September/October issue.
The article, “The Search for Adam,” says that while “many people regard the story of Adam and Eve as a myth,” the scientific evidence is mounting that Adam existed, and the article quotes various creationists to support this case.
Fazale Rana, a biochemist and vice president of Reasons to Believe, a creation science group:
Adam would have been a consummate hunter, an artist, an artisan and craftsman. He would have been the first Tim Taylor from the Tool Time TV program. There’s an obsession with tools and manufacturing. He was a man’s man, but also a Renaissance man capable of art and musical expression. You can imagine Adam conveying his love for Eve by giving her jewelry.
John Morris, an executive at the Institute for Creation Research:
Adam started out as what God intended man to be. … Before the curse, Adam was a superman. Intellectually and in every sense he was probably vastly superior to us. After the curse, I suppose he was in our league, but still quite brilliant.
Really, there’s something bigger at stake than this reading of the Book of Genesis. Consider this account of the debate about intelligent design from the Washington Post, 5 February, 2006.
While the controversy over intelligent design is superficially about scientific facts, the real debate is more emotional. Evolution cuts to the heart of the belief that humans have a special place in creation. If all things in the living world exist solely because of evolutionary competition and natural selection, what room is left for the idea that humans are made in God’s image or for any morality beyond the naked requirements of survival? Beneath all the complex arguments of intelligent design advocates, Georgetown theologian John Haught agreed, ‘there lies a deeply human and passionately religious concern about whether the universe resides in the bosom of a loving, caring God or is instead perched over an abyss of ultimate meaninglessness.’
I think the first sentence, should have “philosophical” in the place of “emotional.” The big Philosophical question concerns our place in the universe. Are we like dogs or are we like gods? And if we are like dogs, does that mean we’re in an ‘abyss of ultimate meaninglessness’ or not? That’s where this was heading for Hume. And maybe for us too.