Determining the validity or truth of an idea or statement isn’t always easy and never has been easy. A fourteenth-century philosopher William of Occam had a useful rule of thumb for this quandary. We now know it as Occam’s Razor, and it is often stated thusly: “The simplest explanation is usually the best.”
The original Latin –“Pluralitas non est ponenda sine necessitate” — adds a wrinkle. This translates roughly, “Multiple variables are not to be posited without necessity.”
A more modern form of this principle is called the Duck test which is a humorous term for a form of inductive reasoning. This is its usual expression: If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.