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.

More information on Occam's Razor can be found on this site, with more information on its current uses here.

Andrew Mattock
05:49PM ET
2004-Feb-01 Occam, to use one of several spellings, puts the damper on intellectuals, philosophers and anyone predisposed to the use of hyperbole or just likes the sound of their own voice.

Dan Tapp
02:49PM ET
2004-Feb-23 Interesting...that's the first time I've ever seen that Latin phrase as the original text. I'd always thought it was something along the lines of
"Non sunt multiplicanda entia praeter necessitatem."",2004-02-18 12:44:48.250000000
204,34,83,"Has a solution to this problem been found and effectively implemented yet?

I have users of my online application that use a shared Mac with IE computer. From what I read above no matter what my webpage instructs the browser to do, it still caches information.
My users have to enter personal information and I am now a little scared that the browser is caching infromation that could be exposed to subsequent users of the computer.
I would appreciate an update. Otherwise, I will have to block mac with IE.

Andrew Mattock
04:24PM ET
2004-Oct-02 Interesting that there have been no further comments on this page. A word or two, even big one's, wouldn't necessarily constitute hyperbole. I guess it's an obscure subject and shows how far out of touch with the masses the two contributors to this page are. That's the simplest explanation!

Kevin Baird
03:50PM ET
2005-Mar-10 The 'Contact' version contains the words 'all things being equal'. Let's assume that explanation x and explanation y for a given phenomenon are otherwise identical, except explanation y requires one more assumption. So go with x, because it's simpler.

If y offers a better (more accurate, more robust, more thorough, whatever) explanation, go with y, even though it's more complicated. The Contact/Zemeckis version has no issue with this decision, because 'all things being equal' is no longer true: y actually offers a better explanation.

So simpler explanations DO tend to be right unless a more complex explanation is measurably better.

Adrian Scott
01:12AM ET
2005-Sep-16 The spelling of 'Ockham' comes from the the fact that the authors name is not "William Ockham" - but "William OF Ockham". Willam came from the village of Ockham, which is not too far from London Heathrow airport.

Lacey
10:11PM ET
2012-May-13
When you explain anything it makes no sense giving many explanations when one is just as good. Really, what sense does it make to give one explanation, then give many more all meaning the same thing, that’s wasted breath.

You know, sometimes its easy to get caught in the trap, because you might be explaining something and based on the look on the person’s face you get the idea that you have to say it differently for them to understand, and before you know it, you have gone on and on about the same thing in about six different ways, leaving the person wanting to give a piece of advice from Ockham

R.T. Lindsay
05:20AM ET
2013-Jan-02
My philosophy lecturer gave it to me like this: “Don’t multiply entities beyond necessity”, which means in effect that unless a good positive reason can be given for believing that X exists, one ought to believe that X doesn’t exist. In this context, Ockham’s razor amounts to the idea that an explanatory hypothesis is better if it postulates the existence of fewer entities, or fewer kinds of entities, than rival explanations.

ron muir
11:36PM ET
2013-Sep-27
Andrew Mattock blows his credibility by his incorrect use of the word “one’s”.

Collette Walsh
12:55PM ET
2013-Dec-04
Surely once you have an alternative hypnosis to explain the final dot on your hypothetical graph, then this new hypothesis is now the new simplest hypnosis and as such supports ockhams razor. Just a thought

Hautt
01:27PM ET
2014-Sep-22
It also applies to philosophy. Why have two gods when one will do?

Andrew Mattock 05:49PM ET 2004-Feb-01	Occam, to use one of several spellings, puts the damper on intellectuals, philosophers and anyone predisposed to the use of hyperbole or just likes the sound of their own voice.
Dan Tapp 02:49PM ET 2004-Feb-23	Interesting...that's the first time I've ever seen that Latin phrase as the original text. I'd always thought it was something along the lines of "Non sunt multiplicanda entia praeter necessitatem."",2004-02-18 12:44:48.250000000 204,34,83,"Has a solution to this problem been found and effectively implemented yet? I have users of my online application that use a shared Mac with IE computer. From what I read above no matter what my webpage instructs the browser to do, it still caches information. My users have to enter personal information and I am now a little scared that the browser is caching infromation that could be exposed to subsequent users of the computer. I would appreciate an update. Otherwise, I will have to block mac with IE.
Andrew Mattock 04:24PM ET 2004-Oct-02	Interesting that there have been no further comments on this page. A word or two, even big one's, wouldn't necessarily constitute hyperbole. I guess it's an obscure subject and shows how far out of touch with the masses the two contributors to this page are. That's the simplest explanation!
Kevin Baird 03:50PM ET 2005-Mar-10	The 'Contact' version contains the words 'all things being equal'. Let's assume that explanation x and explanation y for a given phenomenon are otherwise identical, except explanation y requires one more assumption. So go with x, because it's simpler. If y offers a better (more accurate, more robust, more thorough, whatever) explanation, go with y, even though it's more complicated. The Contact/Zemeckis version has no issue with this decision, because 'all things being equal' is no longer true: y actually offers a better explanation. So simpler explanations DO tend to be right unless a more complex explanation is measurably better.
Adrian Scott 01:12AM ET 2005-Sep-16	The spelling of 'Ockham' comes from the the fact that the authors name is not "William Ockham" - but "William OF Ockham". Willam came from the village of Ockham, which is not too far from London Heathrow airport.
Lacey 10:11PM ET 2012-May-13	When you explain anything it makes no sense giving many explanations when one is just as good. Really, what sense does it make to give one explanation, then give many more all meaning the same thing, that’s wasted breath. You know, sometimes its easy to get caught in the trap, because you might be explaining something and based on the look on the person’s face you get the idea that you have to say it differently for them to understand, and before you know it, you have gone on and on about the same thing in about six different ways, leaving the person wanting to give a piece of advice from Ockham
R.T. Lindsay 05:20AM ET 2013-Jan-02	My philosophy lecturer gave it to me like this: “Don’t multiply entities beyond necessity”, which means in effect that unless a good positive reason can be given for believing that X exists, one ought to believe that X doesn’t exist. In this context, Ockham’s razor amounts to the idea that an explanatory hypothesis is better if it postulates the existence of fewer entities, or fewer kinds of entities, than rival explanations.
ron muir 11:36PM ET 2013-Sep-27	Andrew Mattock blows his credibility by his incorrect use of the word “one’s”.
Collette Walsh 12:55PM ET 2013-Dec-04	Surely once you have an alternative hypnosis to explain the final dot on your hypothetical graph, then this new hypothesis is now the new simplest hypnosis and as such supports ockhams razor. Just a thought
Hautt 01:27PM ET 2014-Sep-22	It also applies to philosophy. Why have two gods when one will do?