William of Ockham and “Ockham’s Razor”

In the Central Middle Ages (c.1050-1350), the big-boss philosophers were the scholastics, and this guy here was one of the biggest. May I introduce to you the Franciscan friar and famed developer of epistemology (the philosophy of how we know things), William of Ockham. He lived from 1285 to 1347 and settled in many different parts of Western Europe, writing about logic, theology, and political philosophy. We know him today because of the philosopher’s tool called “Ockham’s razor.”. Ockham’s razor is a way to think about how to best understand the causes of things. A lot of times it is phrased something like “the simplest explanation is preferable to one that is more complex.” So, if you’re a medical doctor, and a patient comes to you with a rash, it might make more sense to check for allergies than to suspect Leprosy. “When you hear hoofbeats, think horses, not zebras,” goes the saying. Diagnosing “zebras” is the common mistake medical interns stereotypically make when they are new to the field.

However, Ockham’s articulation was more nuanced, and rightly so. He said “numquam ponenda est pluralitas sine necessitate,” or “plurality must never be posited without necessity.” This means, don’t stack extra explanations if you can explain with less. This refinement is important, because of course the simpler explanation is not always correct. A flying spaghetti monster didn’t magically make the ice cream in my freezer, even though that is a quicker thing to imagine than it is to describe the various chains of causality that actually led to ice cream being in my freezer.

Ockham’s razor is better used when 1) all the best known evidence is taken into consideration, and 2) the theory can be tested for falsifiablity. As Albert Einstein wrote: “the supreme goal of all theory is to make the irreducible basic elements as simple and few as possible without having to surrender the adequate representation of a single datum of experience.”