Sunday, August 23, 2009

Explanations

I just read Robert Wright's latest piece on evolution in the Sunday NY Times. He tries too hard, in my opinion, to reconcile science and religion. But he's a good guy. He wrote a very nice (and personally honest) piece on a meditation retreat.

At the crux of Wright's evolution piece is the question of scientific explanation. What do we think needs explaining and what will count as an explanation of it?

We as human beings seem inclined to ask why questions. It's a good question whether this is built-in. That is, have we evolved to ask such question? And if we have evolved to ask such question, what evolutionary advantage does it give us?

It seems to me that the answer is right there in the second question. It could be asked, "If we have evolved to ask such question, why did we evolve that way?" In other words, Why do we ask why questions? What is the purpose in doing so?

Again, the answer is in the question. We are asking for the purpose of something. According to Dictionary.com, purpose is defined as "the reason for which something exists or is done, made, used, etc." The assumption underlying why questions is (often) that there is a reason for something to exist or to be the way it is. This is a teleological perspective. It assumes that something is the way it is because it serves a purpose being that way. When asking a why question, one is often asking what purpose is served by the thing or phenomena being the way it is.

Why questions can be strung out indefinitely. Once one has a presumed answer to one why question, i.e., a purpose to be achieved, one can always ask why that purpose should be achieved. The ultimate answer, of course, is religion: God wanted it that way. That's where the why questions stop: there is no questioning God's will. Whether or not that's satisfying, it terminates the chain of questions, which is at least a relief. It seems then that one can trace a fairly direct route from why questions to religion.

But we never did answer our question: why did we evolve to ask why questions? The answer is a bit subtle. First of all, from a scientific perspective, there are no answers to why questions. Science answers how questions: how did something come about. Science provides mechanisms that show how phenomena are produced. Of course we can then ask why the mechanism works the way it does—really how the mechanism is implemented. That's a perfectly good question and leads to more and more science. So either way one goes, why or how, there is no apparent natural end to questions.

I said that in the why direction we use religion to terminate the chain. In science we have reached a point at which we find we must attribute some events to chance. At the quantum level, there are no mechanisms to appeal to. We just say that certain events happen with a certain probability.

Is that any more satisfying that attributing an ultimate purpose to God's will? The answer "it's random" does have some scientific basis. We know how to test for randomness—or at least we have a number of tests that we use when trying to determine whether or not something is random. Quantum events pass those tests. But not everyone is happy. Einstein wasn't. "God doesn't play with dice," he said.

Besides randomness physicists also think in terms of laws (the conservation of matter and energy, for example, or F = MA). What makes those laws applicable to nature as we know it? That is, how do those laws work? What is the mechanism behind the laws? There are no answers to that other than, that's the way it is. It often happens that we find explanations for some laws in terms of other deeper and more general laws. When we are successful in doing that, we have come up with an answer to a how question. Perhaps string theory will provide how answers to all our existing laws of physics. But then one can always ask what makes string theory work the way it does. So presumably there will always be unanswerable—or at least unanswered—how questions.

This is another place where religion often tries to step in. By postulating God as something like a first cause or the ultimate essence of nature that makes it be the way it is, religion attempts to end the chain of how questions. But it doesn't work so well in this direction. Since we are asking how questions, that is, looking for mechanisms, the obvious question is how does God work? What is the mechanism that makes God work the way he does. Religion, of course, says that's not a question one can answer. So in effect, the God-as-first-cause answer is essentially the same as the law-of-nature answer, namely, that's the way it is. Since the two are equivalent in explanatory power, i.e., no explanatory power, that's-the-way-it-is is a better answer than God-as-first-cause because it doesn't arbitrarily postulate an entity for which there is no evidence and which, once postulated, provides no further intellectual leverage.

But we still haven't answer our question about why we evolved to ask why questions. At this point we should know that what we really mean to ask is how we evolved to ask why questions. We know the answer to that how question: the mechanisms of evolution. And how do attributes come into existence and then persist once in existence? The answer is to look to the survival and reproduction advantage that attribute offers.

Now we can ask, what survival or reproductive advantage does thinking teleologically give us? It doesn't help when thinking about how the world works with respect to its physical functioning. Physics and chemistry are not teleologically driven. They are how driven. But what about biology? Does it make sense to ask, for example, why my cat just drank some water from his bowl? In asking that question, I'm not asking for the physics behind my cat moving to his bowl and then drinking. I'm really asking what purpose it serves my cat to drink water and when does he do that. The answer, of course, is that he drinks when he is thirsty, and he does that because if he didn't he would die.

But isn't that a teleological answer? Am I really saying that teleological, i.e., why, questions are appropriate for biology?

No I'm not. The biological answer to why my cat drinks when he's thirsty is that he evolved to do that. And more fundamentally, if he hadn't evolved to do that, he wouldn't be here right now.

Is that a real answer? It sounds like the same sort of answer as that's-the-way-it-is. Well, it isn't that sort of answer. The short story is that evolution works by generating variations among living organisms. Those variations are random. Most are detrimental to the survival of the organism. But some are advantageous, i.e, organisms that have them are more likely to survive and reproduce. The advantageous one persist. Feeling thirsty when one's body needs water and then drinking when one feels thirsty is a very complex but valid example of such a variation. Organisms that don't do that don't survive and reproduce.

Evolution is the process of generating new mechanisms and keeping the ones that work. The ones that work look to us like they were invented for a purpose. That's not true; they just happen to help the organism survive and reproduce.

But again, how is it advantageous to us to think teleologically? Finally, here's the answer. The behavior of many biological organisms appears teleological. When we think about their behavior teleologically we give ourselves a better sense of how that organism functions in the world. Knowing how organism function in the world gives us a better chance to survive and reproduce.

It's important to know, for example, that a mother bear will fight fiercely to protect her cubs. That's a teleological explanation of her behavior. And if we could get inside the mother bear's head, that even may be how it might appear to her.

Doesn't that mean it is ultimately teleological. No. The mother bear evolved to act in that teleological way because it improved the survival chances of her cubs. Understanding the mother bear's behavior in teleological terms makes sense even though that behavior, teleological as it may appear to both us and the mother bear, is fundamentally a mechanism that helped the mother bear's genes persist.

And thinking about it teleologically helps us survive and reproduce, which is why it is advantageous to us to have evolved to think teleologically and to ask why questions. So why did we evolve to ask why questions? Because thinking about nature in teleological terms helps us survive and reproduce—even though that's not the way nature really works!

1 comment:

C├ędric Gommes said...

According to Aristotle, a phenomenon is always the result of at least 4 causes: a material cause, a formal cause, an efficient cause, and a final cause.

A common example is that of a house. Its material cause is the brick it's made of; its efficient cause is the carpenter's skill;
its formal cause is the plan of the architect, and its final cause is to be inhabited.

As you mention, modern science considers only efficent causes, but this is only a recent idea.