Monday, March 17, 2014

Facts, Brute and Otherwise

Prof. Feser has responded at length to some comments I made on one of his posts. As usual, I thank him for his time and attention to my comments.

In those comments, I proposed the example of lightning striking a tree and starting a forest fire. I claimed that the lightning is still an explanation for the fire, even if the lightning itself was a brute fact (i.e. a fact having no explanation).

I realized (eventually) that my example was not the sort of explanation Feser had in mind in his original post. My example was a horizontal causal chain, in which one event causes another, which causes another, and so on, while Feser's original claim was about vertical explanatory chains: one level of explanation is in turn given a more detailed description by a lower-level explanation, which is in turn given a still-lower-level explanation. (The picture I have in mind is, for example, of a broken window that is explained at one level by the rock that hit it, but at a lower level by the fracturing properties of glass and the stresses imposed by the rock, and those properties are in turn explained by the properties of the molecules of which the glass and the rock are made, and so on.) So my example wasn't really relevant to Feser's point.

In his new post, though, Feser clearly does intend his point to apply to horizontal causal chains, so perhaps the forest fire example is relevant after all. Let me add a few more remarks.

For some reason, I'm more sympathetic to the idea that the brutishness of facts propagates vertically. I'm not sure why my intuition differentiates between the horizontal and vertical explanatory chains. The goal of physics is to describe the way the universe is in as simple and efficient a manner as possible. We physicists suppose that everything physical can be explained at bottom by the Standard Model of elementary particles, but we are content to take that theory as a brute fact. (Well, not really "content": we are always striving for a deeper explanation which will explain the structure and parameters of the Standard Model. But if we found such a theory, we would take that as a brute fact.) So in some sense the answer to any physical question is, "That's just the way the universe is." But that doesn't mean such explanations aren't useful.

Any explanation of a fact A will necessarily be in terms of other facts B, C, and D. (Unless A is self-explanatory, whatever that might mean.) B, C, and D, in turn, are either self-explanatory, or brute facts, or they are explained in terms of some further facts E, F, and G. So the whole thing can only bottom out in facts that are either self-explanatory or brute. (It seems to me that this much is true of both vertical and horizontal chains.)

If I read the professor's remarks correctly, he is saying that something can only be a real explanation if it bottoms out in only self-explanatory facts. (And that this is true of both vertical and horizontal explanatory chains.)

My response is that, if this is true, then there are hardly any examples of real explanations. In fact, maybe there has never been a real explanation in the history of humanity. For (nearly?) all actual explanations leave something else unexplained.

For instance:
  • I can explain why that pot of water is boiling by noting that it has been on a hot burner for 15 minutes. 
  • I can explain why the window broke by noting the rock that hit it.
  • I can explain why I slipped and fell by noting the ice on the sidewalk.
People do not normally require a deeper explanation in order to consider these real explanations. I do not need to understand the molecular structure of water and its relation to the boiling point in order to consider the hot stove to be the explanation for the boiling pot. I don't need to know about the breaking stress of glass to consider that the rock explains the broken window. I don't need to understand how ice lowers the coefficient of friction to think the ice explains why I slipped.

What I'm saying is, any actual example of an explanation always leaves some loose ends. The regularities themselves are enough for us to claim we have an explanation: heat boils water, rock breaks window, ice makes sidewalks slippery.

Now, what Feser seems to be saying is that, though we might not know what the explanation is for the explaining facts B, C, and D, we must at least believe that there is an explanation for those facts. Otherwise we don't really have an explanation.

To this I can only respond as Keith Parsons did: I don't see why I should think this. If all actual examples of explanations leave something else unexplained, why should I deny that these are true explanations? It makes more sense to me to provide an account of explanation that reflects how we actually use explanations than to provide an account which declares by fiat that no real-world examples of explanation are true explanations.

Feser challenged me to provide an alternative account of explanation. I have done so before in previous discussions, and have not to my recollection had a response, but I am happy to repeat it here.

Consider the D-N model of scientific explanation. According to this model, an explanation of an event A consists of two things:
  1. A list of natural laws L1, L2, L3....
  2. A list of conditions C1, C2, C3.... that guarantee the laws apply in the case A.
So we can provide a D-N explanation of the forest fire as follows:
  1. L1: Lightning causes fires.
  2. C1: There was a lightning strike.
Under the D-N model, the lightning strike is an explanation of the forest fire, even if we have no explanation of the lightning itself (i.e, it was a brute fact).

Let's return to the boiling pot. I can, in principle, carry my explanatory chain vertically downward, explaining the molecular properties of water in terms of the quantum mechanical properties of the atoms,  and the properties of the atoms in terms of the Standard Model. There I bottom out in brute facts, from my physicist's point of view.

So here's my counter-challenge for Professor Feser: give a real explanation - in his own sense - of why the water is boiling: an explanation that bottoms out only in self-explaining facts or necessary truths.

Finally let me note that scientific explanations of the kind I've been talking about have a stunning record of success. Engines, TVs, computers, cell phones - all of modern technology stems from our ability to explain things in terms of unifying regularities. In contrast, Aristotelian explanation has been around for more than 2000 years: what practical successes can it claim?

Tuesday, March 4, 2014

Bicycles and Universes

I have often imagined debating William Lane Craig myself, and thought out the ways I would respond to his arguments. I have often, while listening to Craig's debates, wondered why his opponent didn't call him on some claim that was simply untrue. Were they just being polite, or did they not realize the falsity of the claim?

I think I may be cured of these fantasies. Sean Carroll did brilliantly in the debate - far better than I could ever have done. He didn't hesitate to say outright, "That's just false!" And his deep expertise in cosmology was the perfect counterpoint to Craig's quote-mining of partially-understood physics papers.

I have only a couple of comments on style and content. I thought Sean did a good job of pointing out where Craig failed to respond to the argument. (This is an area where Craig usually excels.) But instead of merely pointing it out, he ought to have taken the opportunity to summarize his argument again, for those who might not have understood it completely the first time.

Craig, as usual, excelled in his logical organization and presentation of his argument. His concluding summary nicely recalled his original point: not that he was out to prove God's existence, but that modern cosmology lends support to one of his premises.

Here Carroll really missed an opportunity. He ought to have said, briefly and succinctly, that modern cosmology lends no support at all the premise that the universe had a beginning. What we can say for sure is that the universe was a very different place 13.7 billion years ago. But any statement about what happened before that is very speculative and unfounded in established science. There are models in which time has a beginning, and there are models in which it doesn't: none of these models are established science, and so nothing can be deduced from them about a beginning.

One final missed opportunity: when Craig asked, quite reasonably, "If universes can just pop into existence, why not bicycles? What's the difference?" (from memory, not an exact quote) Sean could have responded that there is an obvious and crucial difference: bicycles are things that exist within time, while universes are not. On the contrary, time exists within a universe. For all Craig's bluster about simultaneous causation in the Q&A session, causality has to do with what brings about a change. And for there to be change, there must be time. Since a universe is not something that happens in time, the causality issue doesn't apply.

I think Sean probably had something like this in mind in his argument about the a cosmological model as a self-contained description needing no outside cause, but it would have been nice to respond to Craig's question with a specific difference that clearly matters.

Monday, March 3, 2014

Craig, Carroll, and Cause

Since I've been reading about causes, one part of the debate that stood out for me was the fact that neither Carroll nor Craig tried to define "cause." In terms of the debate, this was undoubtedly wise: a long digression on the different definitions of "cause" would probably have lost most of the audience. But it was bad philosophy. Carroll tried to explain that, for a physicist, having a consistent mathematical model that comports with the experimental evidence is all we need. Any discussion of causes and effects will proceed from that model. Craig simply kept repeating his argument from incredulity: a universe can't just pop into being without a reason.

But certainly, how we think about causation affect our ideas on whether a self-contained universe needs a cause.

(By the way, this issue is independent of whether the universe in question has a beginning or not. While it might seem intuitively that a universe that begins is more guilty of "just popping" into existence, it has often been argued that a universe that is infinite in time is no less in need of some sort of external cause or explanation.)

On Hume's regularity view, causation is a matter of constant conjunction: to know that A causes B, we need to know that A is always followed by B. So what we need to do is to make lots of observations of deities, and if "Let there be light!" is always followed by a universe popping into existence, then we can conclude that gods cause universes.

On Wesley Salmon's analysis, a causal process is one that can carry some sort of a mark that transmits from the cause to the effect. It would seem, though, that if God is perfect, God is impossible to mark. Thus, we could never tell if a mark can be passed to the universe.

Another modern approach is to take causation to involve the transmission of a conserved quantity, like energy or momentum. But neither the theist not the atheist would claim that a universe that has a beginning in time was initiated by a transfer of pre-existing energy, so in this case there is no possibility of a cause.

On the Aristotelian-Thomian analysis, causation involves a potentiality becoming actuality, and an external cause is necessary to tip something into actuality. A universe is obviously possible (if it were impossible we wouldn't be here), so on this analysis an external cause is needed to make the universe actual.

So it seems possible, in principle at least, that both Craig and Carroll are right: differing definitions of "cause" may yield different conclusions about whether a self-contained universe requires a cause.