# Occam's Razor: Do you really know what it means?

posted 1999-Dec-13
In Contact, Dr. Arroway (played by Jodie Foster) is asked "Do you know what Occam's Razor is?" to which she responds (roughly):

"Yes, it's the scientific principle that, all things being equal, the simplest answer is usually the right one."

No it isn't! It's not it's not! I keep hearing people refer to Occam's Razor (also, I discovered, acceptably spelled "Ockham's Razor") as though it means that simpler explanations tend to be right. Occam's Razor is this:

"one should not increase, beyond what is necessary, the number of entities required to explain anything" - William of Ockham

[UPDATE: The page from which I got that quote has rather liberally translated the original. I'm now finding a variety of english translations for the original latin "Pluralitas non est ponenda sine neccesitate", such as "Entities should not be multiplied unnecessarily," and "Plurality should not be posited without necessity." Some other night I'll do a consensus search and find the most accurate translation.]

Occam's Razor, in my words, means that if you have a working explanation for something, don't go making it more complicated. Which, yes, means that the first hypothesis you try is the simplest one...but that doesn't mean that it's RIGHT because it's simple, it just means that it's the best explanation to try until it doesn't work.

For example, say you plot three points on a graph, all in a line, and are trying to come up with a function which will describe the rest of the points you plot. There are an infinite number of equations which will pass through those three points, but the best assumption to make is that all the points will lie along the line. Occam's razor says so. What Occam doesn't say is that choice is the "right" one just because it's simple. If you plot a fourth point which doesn't end up in line with the other three, is there egg on Occam's face? No way, baby.