Geoff Gannon March 25, 2006

Off Topic: On Cause and Effect and Inherent Randomness

This is an off-topic post (i.e., it doesn’t pertain to investing). Below, I have reprinted a comment written in response to my post On Technical Analysis and my response to that comment.

Amanda Gerrish writes:

Good article. However, I must take exception to your idea that there are no truly random events in nature. Quantum physics proposes that all quantum processes (sub-atomic events) have an inherently random element. These events are not apparently random because we don’t have enough information, or we don’t have the correct model. They are inherently uncertain. At best, we can assign probabilities. Since all macroscopic events (including human actions, markets, the weather, etc.) are built upon microscopic (sub-atomic) events, this implies that there is an inherent, irreducible uncertainty or randomness to all events. Well, at least, if you believe quantum mechanics.

My response:

You make a good point about quantum mechanics, but I have seen it taken too far. For instance, one philosopher argued that an inherently random element supports the case against the existence of God (or a prime mover of any sort). I have a few problems with this argument. The biggest problem is that it favors accepting the existence of an uncaused event over the prudent course of withholding judgment because far too little information is known.

When I say far too little information is known, I mean simply this: an inherently random element does not fit with the law of cause and effect. So, we have three options. One, we could throw out the law of cause and effect and assume that the best we can ever do is establish correlative rather than causal relationships. Two, we could throw out the idea of an inherently random element in quantum mechanics. Or, three, we could withhold judgment, because we feel our understanding of these matters is insufficient.

I favor the third course, largely because I think our understanding of time remains inadequate. In several different places, the study of physics has bumped up against our ignorance of what time really is, and just how it works in the extremes. This gets us into some very strange sounding discussions. However, we will need to address them eventually.

Are there more dimensions than we perceive? Is our perception of time flawed? Can actions occur outside of time? Is any “inherently random element” actually the result of a cause that did not occur in the dimensions we perceive? Simply put, is it possible we can’t perceive the cause, or even the general laws under which the cause operates, and therefore can not conceive of the effect as being anything but random?

I wouldn’t put it into these words, but I think eventually people will say that it’s possible there may be causes operating “outside of time” – simply meaning that there may be causes that do not operate according to the principles of time as we know them. As strange as it sounds, I think the logical idea of a law of cause and effect is actually a far more durable model than the empirical model of the four dimensions we perceive.

It’s quite possible none of us will live long enough to know who is right and who is wrong. But, my money is on the law of cause and effect to outlast the simple four dimensional model of physical reality.

So, while I wouldn’t say I don’t believe in quantum mechanics, I would say that we may all have a different view of quantum mechanics as our understanding of time evolves. I believe a universal theory of cause and effect is likely to outlast most of these newer theories.

The best model is the most useful model. So, I have no problem with quantum mechanics as a model – even though it is irreconcilable with a model of reality that incorporates a universal law of cause and effect. The fact that the two models contradict each other is unfortunate, but I don’t think it should stop us from using either.

The best course is to simply suspend belief in a strong theory of cause and effect when dealing with quantum mechanics, until physics provides an integrated theory. There has been some movements in this direction. It might happen. More likely, all of this will remain in the realm of pure conjecture for the rest of our lifetime.

Amanda Gerrish replies:

I agree with your comments. To go a step further, there are interepretations of quantum mechanics, such as the Bohm Interpretation, which restore causality:

This interpretation is by no means universally accepted, so the question of a truly random process in nature is currently an open one.

If the Bohm interpretation is correct then it would mean that all processes in nature are not random, but some features (i.e., the “hidden variables” in Bohm’s theory) are unknowable, so that they are effectively random, given the limits of our knowledge.

Even in classical quantum mechanics, the concept of cause and effect is assumed to hold “on average”, meaning that, statistically, some events are overwhelming probable, or improbable. For example, according to quantum mechanics, there is a some chance that I could walk through a wall unimpeded. However, it is so ridiculously small as to effectively be impossible. This maintains cause and effect at the macroscopic level while allowing probabalistic events at the microscopic level. (Electrons can easily tunnel through matter under the right conditions, but I can’t walk through a wall.) Your belief in a strong theory of cause and effect is quite reasonable.

Read “On Technical Analysis”