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Shaving with Occam's Razor

by Richard Gant

December 30, 2016

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Donate I was on Twitter on Christmas Eve, wasting time that should have been spent working out what my very first blog post should be, when I saw the following tweet:
sorry to bother you @BrianDunning -& plz forgive me if it's been covered- but people butchering occam's razor needs to be addressed i think
Well, there was my inspiration. Sure, Brian Dunning responded to the tweet by pointing out that it will be addressed in Principles of Curiosity (go fund it on GoFundMe), but it got me curious. And indulging my own curiosity is why I write.  So, let's start with the obvious question:

What is Occam's Razor?

Occam's razor is bandied about quite a bit on the internet, particularly among skeptical circles. Most of my life, I'd assumed that it was identical to the famous Sherlock Holmes axiom from The Sign of the Four (1890): "How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?" And it turns out that, for most of my life, I've been wrong. This quote, although it works along similar lines, is not Occam's razor.

Occam's razor is actually based on two "laws," the lex parsimoniae (or law of parsimony) and the lex pluralitatem (or law of plurality, and I'm trusting Google Translate for the Latin on that one). Both must be applied to fully make use of the razor. Even then, as we'll soon see, it must also be remembered that the razor does not guarantee accuracy. It is merely a tool that gives you a starting point for reasoning about a problem.

The lex parsimoniae can be stated "frustra fit per plura, quod potest fieri per pauciora," and usually translated into English as "it is pointless to do with more what can be done with fewer." The lex pluralitatem on the other hand, can be stated "numquam ponenda est pluralitas sine necessitate," "plurality is never to be posited without necessity." Combining the two laws, Occam's razor is, simply put: "Keep it simple. Because, all else being equal, the simplest answer is most likely to be the correct one."

Is Occam's Razor an Actual Law, Then?

Well that depends on what you mean by "law," really. It's not considered one of the axiomatic laws of thought, though, so it's not considered to be a foundational principle of philosophy. Really, it's a maxim. A guideline. A tool to help you cut through the Gordian knot of options and alternatives that come up when you research anything, allowing you to pick a place to investigate. It's not foolproof, though, because the real world is messy and determining what is the "simplest" explanation with the "fewest" moving parts can be extremely difficult.

Occam's razor is a tool, just like any other tool. Use it correctly, and it will work well. Use it incorrectly, and you risk injuring yourself or damaging its usefulness. If you don't believe me, try using a coping saw to hammer a nail into a two by four. (Note: Do not actually try this. It will end in tears and blood.)

Butchering Occam's Razor

It bears repeating: Occam's razor is a tool, not a rock-solid unbeatable guide to The Truth. The utility of the razor is that it allows you to make a choice between two or more possible solutions, but those possible solutions need to be equally likely before application of the razor points with any accuracy towards any sort of accurate result. Allow me to illustrate, absurdly, using gravity as an example.

One explanation for gravity is that it is caused by an object's mass warping space-time. Other objects moving through space-time have their trajectories altered by the warp, deflecting them into a new trajectory. If the mass is sufficiently large, space-time is warped so much that the moving object is deflected towards the warping mass, creating what is perceived as "gravitational attraction." A second explanation is that the Flying Spaghetti Monster, in His noodly wisdom, holds us to the Earth in his loving pasta embrace. An ill-advised application of Occam's razor would hold that the FSM explanation is most likely the correct one, because it only postulates one entity (the FSM) and is also the simplest (He holds us to the Earth with his noodly love). The warped space-time explanation requires such entities as "mass" and "space-time" and "trajectories" and is, quite simply, difficult to wrap your head around. The only catch about the FSM solution is that it isn't true.

Occam's razor does not, and can not, dispose of facts. Occam's razor only disposes of messy and complicated explanations for existing facts, and even then it only disposes of them until such time as more facts arise. Then, if those new facts reveal that the disposed-of messy and complicated explanation is actually more correct, then Occam's razor needs to be reapplied in light of the new information. Because, at the end of the day, the best explanation for reality is what is really there. All of our tools and principles and laws are just there to help us work that out.

by Richard Gant

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