One of the chief obstacles to understanding is the unavoidable human habit of rationalization. We tend to favor some beliefs, and to resist others, and have a natural tendency to explain away any evidence that leads to conclusions we don’t like. What’s even worse is that most of the time we don’t even realize that we’re doing it. Fortunately there’s a simple rule of thumb that can help us easily separate rationalizations from legitimate explanations.
In a genuine explanation, we describe something in sufficient detail that we can tell what specific, observable consequences would result from our claim being true, as distinct from the consequences that would result if our claim were not true. This makes our explanation testable: since we know what real-world consequences correspond to our explanation being true, we can simply observe the real world and see if those consequences are, in fact, present.
A genuine explanation, in other words, is a tool that helps us distinguish what’s true from what’s not true. Rationalization, on the other hand, has the opposite goal. The purpose of rationalization is to prevent us from telling the difference between a premise that’s true and one that isn’t. The rationalization takes a desired premise, and the observable evidence, and then throws in speculations and supposed extenuating circumstances designed for the sole purpose of making essentially any observed outcome seem consistent with the premise.