The Danger from Occam’s Razor Rhoneil Anthony G. Gabriel
Occam’s Razor is a popular rule-to-thumb within the scientific community. I first heard about it when I studied Physics in UP. Attributed to William of Ockham, a 14th century Franciscan friar, its main premise is Entia non sunt multiplicanda praeter necessitatem or entities should not be multiplied unnecessarily. 1 Stated as a rule-of-thumb, Occam’s Razor is: all things being equal, we should favor the explanation that makes the least assumptions and proposes the least entities. Let me illustrate its use by giving an example. You found muddy footprints of a child on your kitchen floor. You saw your son playing in the backyard a while ago, but he’s not there now. Which of these two explanations would you choose: a. your son entered the house but forgot to wipe his feet; or b. your son invited a playmate over and it is this playmate who forgot to wipe his feet. Since explanation b introduced an extra entity (the playmate) and an extra assumption (that your son invited him), Occam’s Razor suggests that you should choose the simpler explanation which is letter a. Sounds reasonable. Why complicate matters by adding a playmate in the explanation, if you don’t really know if there was a playmate involved? How do we know that Occam’s Razor is valid for most cases? Occam’s Razor is justified in the following manner: 1. aesthetics, simpler explanations are more elegant, 2. pragmatism, simpler explanations are easier to validate and use, 3. informational content, simpler explanations are more compact, and 4. empirical, there seems to be a lot of situations explained by simpler explanations. 2 1 2
From Wikipedia Summarized from Wikipedia
September 2009. Rhoneil works as a senior quality improvement manager for a global electronics company. He is also a professor in business management in a local university. He lives with his wife and two kids in the suburban town of Tanza Cavite in the Philippines.
Of course the aesthetic, pragmatic, informational justifications for Occam’s Razor are not true justifications. Truthfulness is not determined be elegance, usefulness, nor compactness. They’re more like preferences. I think our preference for the simple has to do with our limited cognitive abilities. Because of limitations in our analytical power, we have many cognitive biases (i.e. natural errors in judgment), that tend to favor simplification. Examples are: Anchoring, Stereotyping, the Gambler’s Fallacy, and the Ludic Fallacy. Parsimony, the principle of “less is better”, might just be another bias. Moreover, simpler does not necessarily mean more correct. In many cases, as we learn more about a situation, its explanation is adjusted to make it fit the data better. These adjustments tend to make explanations more complicated. A good example is the adjustment of the elegant and simple Newton’s Laws of Motion to the more complicated but more correct Einstein’s Theory of Special Relativity. Another example is the increase in the number of subatomic particles from a comfortable three (proton, electron, and neutrons) in the mid-20th century, to the present day sixteen in the standard model (six quarks; 3 types of electrons plus their 3 neutrinos; plus the photon, the gluon and the Z and W bosons). Sixteen is likely to be an incomplete count. Pretty soon, it might be easier for students of memorize the list of past presidents than the list of subatomic particles. Maybe the universe isn’t simple; maybe we just like to think that it is to assure ourselves that we have the capacity to understand how it works. This sounds very much like the Anthropic Principle to me. As for the empirical justification that many things are explained by simpler explanations, this is very hard to prove because of the question of what is “simpler”. To my knowledge, nobody has proven the empirical justification yet. Even if we presuppose that the empirical justification is true, however, I’ll still challenge the validity of Occam’s Razor. Occam’s Razor seems valid for easy to explain situations such as the case of the muddy footprints. It is more likely
that your son is the culprit. However, Occam’s Razor seems to lack consistency in explaining more complicated phenomena. For example, living in the distant past, imagine us seeing the sun and the moon rising from the east and setting in the west everyday, without us knowing the real mechanism behind this phenomenon. Which is the simpler explanation: a. the ancient understanding that the sun and the moon are twin globes of light that crosses the sky everyday; or b. that the moon revolves around the earth, the earth revolves around the sun, the earth rotates on its axis creating the illusion of the sun and moon crossing the sky, and that the similarity in size of the sun and the moon is just a lucky coincidence. Back then, it’s likely that people will think we’re crazy if we choose letter b. Of course now, we know that letter b, the more complicated option, is the correct answer. A similar result is derived if ancient people are asked to explain pregnancy. Is what happens: a. the man’s seed (the sperm) is planted in the nourishing environment of the woman’s womb, quite similar to planting seeds in agriculture; or b. that there are actually two half-seeds (the sperm and the egg, two entities) and one half-seed would need to fertilize the other (an extra process) before they settle in the womb. Again, the more complicated answer is the correct one. So, why will I challenge the validity of Occam’s Razor even if the empirical justification is proven to be true? Occam’s Razor is a ruleof-thumb. Rule-of-thumbs are not used in easy-to-explain situations. Since it’s easy to get the correct answer, there is no need for a guide. Rule-of-thumbs are used in complicated situations when there is uncertainty and a guide might prove useful. If Occam’s Razor cannot consistently favor the correct explanation in complicated situations (as in the two examples above), then it’s useless. The danger from Occam’s Razor comes from its use as justification for logical arguments. One example of this, which does disservice to us all, is its use to disprove that God created the universe. The argument goes something like: if we say that God created the universe, then we
added an unnecessary complication because we would need to explain how God came into being; it would be simpler to drop God and just propose that the universe simply came into being on its own. Another Occam’s Razor vs. God example: Since the universe is running fine by itself without need for any external influence, then saying that there is a God is just adding an unnecessary complication. Without dwelling on the existence of God because I’m sure we all have different beliefs, in these two examples, Occam’s Razor is used as a justification for the conclusion as if it is some sort of natural law or long standing theory. Natural laws and long standing theories are part of a web of mutually supporting theories we call science. Since they’re long standing, they serve as foundations for newer theories. They’re very hard to disprove because if we try to, we would need to explain why the newer theories still work when they do not. Also, we see thousands upon thousand of events everyday testifying to their validity. Examples of these are: the Law of Conservation of Matter and Energy proposing that matter and energy cannot be created nor destroyed (we don’t see houses just appearing in thin air, do we?); and the Central Limit Theory proposing that individuals farther away from the average are rarer (we don’t see a lot of big basketball players on the streets, do we?). Because of their interdependencies and tons of supporting evidence, we can safely assume that natural laws and long standing theories as more or less true and they can be used as justifications for logical arguments. Occam’s Razor is neither. We started off this essay saying that Occam’s Razor is just a rule-of-thumb (a heuristic, using a technical term). We further saw that Occam’s Razor does not have any support for its validity and that it fails to consistently favor the correct explanation of complicated phenomena. So, the next time you hear somebody use Occam’s Razor, pause for a minute and think about what it really is.