Hume on causal knowledge

In Early Modern Philosophy we have come to Hume’s critique of causality (Enquiry, section 4). I have always had difficulty getting the nature of his critique straight in my mind. So I sat down to try to put it clearly, and came up with the following. Nothing new or original here – just what I hope is a clear articulation of one of Hume’s great insights.

We all know what happens in the story that begins, “David Hume came to a fork in the road….” The two tines of the fork are marked “relations of ideas” and “matters of fact,” which Hume regards as “the only two objects of human reason.” What makes a true relation of ideas true is the fact that when you try to deny it, you contradict yourself. What makes a true matter of fact true is … a good question. Hume would like to find an answer to it. He observes that every purported matter of fact is founded in one way or another upon cause and effect. From what we immediately perceive we infer a cause; from our memories, we infer a past event; from our past experience of two events being always conjoined, we infer the second from evidence of the first. And so on. So, he claims, if we want to know what makes true matters of fact true, we need to know what makes causal claims true. Hume then proceeds to demonstrate that general causal claims are not relations of ideas, since if you deny a causal claim, you will not thereby contradict yourself (though you will run the risk of sounding silly). But neither are general causal claims matters of fact, since … well, since why? Remember, we are trying to figure out what makes true matters of fact true. We don’t know the answer yet.

Hmm. Well, practically, what Hume ends up assuming is that a true matter of fact is true in virtue of accurately capturing what is present in our experience. So I eat some bread, and it nourishes me. I eat some more, and it nourishes me, too. The true matter of fact issuing from this experience is that the bread I have eaten on these two occasions has nourished me. But typically we also infer something much stronger: that the bread that I will eat in the future also will nourish me, or that bread always has nourishing qualities (under similar conditions). But these claims do not accurately capture what is present in my experience, if only for the reason that the future, let alone what “always” happens, is not present in my experience.

If this is enough to disqualify general causal claims as matters of fact, then Hume has succeeded in showing that causal claims are not objects of human reason. What does that mean? It does not mean that we should be skeptical of causal claims. It means we should not take ourselves to have any real understanding of why they are true. As he writes towards the end of part I of section 4:

Elasticity, gravity, cohesion of parts, communication of motion by impulse; these are probably the ultimate causes and principles which we discover in nature; and we may esteem ourselves sufficiently happy, if, by accurate inquiry and reasoning, we can trace up the particular phenomena to, or near to, these general principles. The most perfect philosophy staves off our ignorance a little longer: as perhaps the most perfect philosophy of the moral or metaphysical kind serves only to discover to larger portions of it [namely, our ignorance]. Thus the observation of human blindness and weakness is the result of all philosophy, and meets us at every turn, in spite of our efforts to elude it or avoid it.

Nietzsche’s American legacy?

Here is an interesting review of the sorts of ways Nietzsche’s thoughts have been received in the U.S. One paragraph in the essay hits upon a worry I have had from time to time:

For all these reasons, Nietzsche often figures in American culture as a sinister guru of the violent and deranged. When Jared Lee Loughner, who murdered six people in his attempted assassination of Arizona congresswoman Gabrielle Giffords, turned out to be a close reader of Nietzsche’s The Will to Power, an old stereotype was confirmed. Indeed, the title of America’s best-known Nietzscheans goes to Nathan Leopold and Richard Loeb, the teenagers who in 1924 murdered a boy with a chisel because they took seriously the philosopher’s belief that the “Superman” is liberated from conventional notions of good and evil. (Their lawyer, Clarence Darrow, blamed the effect of Beyond Good and Evil on their impressionable minds in his 12-hour defence speech.) If you were to include fictional characters, Leopold and Loeb might have a rival in Howard Roark, the arrogant architect in Ayn Rand’s The Fountainhead.

The essay claims that the intellectuals influenced by Nietzsche tend not to be sinister and arrogant assassins. They carefully consider the ideas and incorporate them into further theory making (sometimes judiciously, sometimes not). It is the less studious who obsess over Nietzsche, buy a weapon, and await their opportunity to prove themselves the overman.

One might decry these would-be criminals and accuse them of misreading Nietzsche, but the fact is that Nietzsche’s powerful prose can get people in the mood for some pretty dark goings-on. This fact sometimes causes me to wonder whether it is morally irresponsible to turn young minds on to Nietzsche. I’ll be the first to admit that I myself am too timid to step beyond good and evil, and I really don’t want my neighbors to take that step. If, when I teach Nietzsche, I always face a certain probability of getting some people into a dark mental space where they might do dark things, should I back off and teach, I dunno, Emerson? Any thoughts?

Understanding through neuroscience, unpromising and promising

For any die-hard reductionists out there, here’s an article on the promise of “neuroeconomics”:

Yet it is likely that one day we will know much more about how economies work – or fail to work – by understanding better the physical structures that underlie brain functioning. Those structures – networks of neurons that communicate with each other via axons and dendrites – underlie the familiar analogy of the brain to a computer – networks of transistors that communicate with each other via electric wires. The economy is the next analogy: a network of people who communicate with each other via electronic and other connections.

Well, good luck on that! Similarly, one might hope that we’ll all be better at using Excel spreadsheets if we start studying how electrons move about in the CPU.

On another note, here is an interesting interview with Michael Gazzaniga talking about the interplay between neuroscientific accounts and broader social structures, particularly in discussions of free will:

For me, it [the interplay between mind and brain] captures the fact that we are trying to understand a layered system. One becomes cognizant there is a system on top of the personal mind/brain layers which is yet another layer–the social world. It interacts massively with our mental processes and vice versa. In many ways we humans, in achieving our robustness, have uploaded many of our critical needs to the social system around us so that the stuff we invent can survive our own fragile and vulnerable lives.

This seems to me the way to go. We shouldn’t simply dismiss neuroscience, of course; but the interesting question is how the “bottom-up” causal story connects with the “top-down” causal story.