Effect and Cause, Part 3

“Theory without empirical evidence is mere speculation. Empirical evidence without theory is simply a collection of facts. Theory supported by empirical evidence is science” (From my book, Freedom or Serfdom?”

We’ve discussed how there can be several possible causes for an effect, several theories as it were about how it happened. That of course raises the question, “How do we know which, if any, of those theories is correct?” A good question, an important question, and sadly a question with an unpleasant answer. The simple answer is that, in most cases, the answer is beyond human ability. We cannot know if some new theory will come along, better than what we have. Nor can we know if new data will invalidate what now appears to be a solid conclusion.

Perhaps the best example of this is the physics Isaac Newton gave us. There was a saying that Newton was lucky, there was only one universe and he got there first. At the start of the twentieth century it looked like physics was complete, only a few minor questions to answer and all would be known. Scientists regarded Newtonian physics as essentially a perfect theory, well established and never to be overturned. Then along came people like Einstein, Bohr, and Planck. Today we know that Newton’s physics is only an approximation to reality, a great approximation for most conditions, but an approximation that breaks down at very high speeds or very small sizes. Newton’s physics can still help us put a man on the moon, but fails if that man travels at speeds approaching that of light, and it fails when we try to describe the motion of an electron.

So what can we do with our theories? We really need some understanding of cause and effect, so how do we decide which theories to, at least provisionally, accept? Books have been written on the problem so we will obviously not get a full answer here, but we can make a start, and that start will suffice in most cases. There are at least four characteristics we require:

First, the theory must be in agreement with data. Newton’s theories met this requirement until new data showed them to apply only under certain conditions.

Second, theory must in some sense be verifiable. Philosopher of science Karl Popper said that a theory must be falsifiable. It must be conceivable that experiment produces a result contrary to the theory. A classic example is that some might claim that there are invisible, undetectable elephants in the room. If they are undetectable, the theory cannot be falsified. A more important example is the claim that socialism is the best economic system, if only the right leaders are in charge. That theory cannot be falsified because any contrary data is explained away with the claim that it wasn’t real socialism because the wrong people were in charge. Thus the idea of science supporting socialism fails Popper’s test, those claims are not science.

Third, though not a strict requirement, it is useful if the theory predicts something verifiable but previously unknown and not consistent with competing theories. Einstein’s general theory of relativity did this with its prediction of how gravity affects light, a prediction since verified.

Fourth, again not a strict requirement, but we want the theory to be as simple as feasible. This is known as Occam’s Razor, we prefer the simplest theory that fits the facts. That is a useful rule to pick which theory we will find most easily used, but of course does not preclude some more complicated theory working better when more is known.

With all that, we have some indication of which theories we might accept, but there is more. We must keep our minds open. A theory may offend our sensibilities, but Nature cares not at all about what we want to be true. We may want to think there is no difference between ethnic groups, but Nature disagrees, at least in the sports world. Blacks in the U.S. are mostly of West African extraction and they dominate in the NFL and NBA, but are not known for distance running. Meanwhile, Kenyans are not famous as sprinters, but they pretty much own distance events like the Boston Marathon. No that is not reason to discriminate, all should have equal opportunity to try. It is, however, reason to expect that different groups will have different outcomes.

One thing we should not require is that the theory make sense to the human mind. In fact, any real advance in science tends to sound weird, sometimes downright crazy. During one conference on quantum physics, Niels Bohr was quoted as saying, “We here in the back are agreed that your theory is crazy. The question which divides us is, is it crazy enough?” Bohr understood that progress means change, sometimes radical change. (However, that does not mean that change is progress. Sometimes change can be detrimental. Let us not seek change for the sake of change.)

If we can find theories that fit the facts, are verifiable, and guide our actions appropriately, that is about all most of us can hope for.