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William of Occam is sometimes called the founder of European empiricism. He is famous for a method for solving problems called Occam’s Razor. The answer with the fewest obscure assumptions is usually the best.

William of Occam

William of Occam’s home town has a stained glass window. (at 51.2980 -0.4716)

William of Ockham

William of Ockham portrayed in stained glass window.

Apparently a straight English statement of what Occam wrote is, “Nothing ought to be posited without a reason given, unless it is self-evident or known by experience or proved by the authority of Sacred Scripture,” but various ways of stating Occam’s Razor have been found in an Internet search:

“With all things being equal, the simplest explanation tends to be the right one.”

“The explanation requiring the fewest assumptions is most likely to be correct.”

“Entities should not be multiplied beyond necessity.”

“One should not make more assumptions than absolutely necessary to try to explain something.”

“Entia non sunt multiplicanda praeter necessitatem.”

“Keep things simple.”

“Do not multiply entities beyond necessity.”

“Entities should not be multiplied unnecessarily.”

“Pluralitas non est ponenda sine neccesitate.” (Entities should not be multiplied unnecessarily.)

“Plurality should not be posited without necessity.”

“All things being equal, the simplest solution tends to be the best one.”

“When you have two competing theories that make exactly the same predictions, the simpler one is the better.”

“If two theories explain the facts equally well then the simpler theory is to be preferred”

“It is pointless to do with more what can be done with fewer.”

“Nothing ought to be posited without a reason given, unless it is self-evident or known by experience or proved by the authority of Sacred Scripture.”

“It is vain to do with more what can be done with fewer.”

At some point the sentence, “You defend me with the sword and I will defend you with the pen.” was used by Occam.


I prefer – Obscure assumptions shouldn’t be multiplied. 

Assumptions shouldn’t be compounded. Sometimes a simple statement is founded on a long train of unverifiable assumptions and although the statement may seem simple and feel right it may be based on wishful hopes.

Oversimplification is often based on obscure assumptions and gets one into more trouble than it gets one out of. Robert McNamara, the US Secretary of Defense during the Vietnam era, was asked how he made decisions in complex situations. What I remembered he said was, “Gather just enough information to make the right decision.” That sounds like an application of Occam’s razor, and it still seems to me like a reasonable procedure, and properly waffles on the right amount, but in searching for this supposed quote, all I found was, “But all reality can be reasoned about. And not to quantify what can be quantified is only to be content with something less than the full range of reason.” If only the right data were used in the right way, not respected for data’s sake.” That is from the “Fog of War” interview. It’s a complex problem making the right decision, but a guide would be just enough information to make the right decision

If the quote at the beginning of this post is accurate then Occam would have chosen angels as the reason our heavenly planets behaved as they do. He would have rejected the later and more complex theories of Newton and modern astronomers. Of course with more information, Occam as an intelligent and informed modern man would find angels too simplistic and would have sided as modern science as having the fewest obscure assumptions.

What Ockham Really Said by Jacques Vallee is a short article that attempts to clarify what Occam was probably thinking, rather than what most quotes imply that he was thinking. A common way of stating Occam’s Razor is, “Keep it simple – stupid.”

Perhaps a better approach to coping with excess information is to first consider the end to be achieved. The problem then evolves into a decision leading to action. If the decision is wholly in the mind and if it doesn’t influence some future action it remains within the mind and evaporates into nothingness when the brain fails. Collecting unusable and unused information wastes time and effort. Perhaps a better statement would be,

“Collect enough information to do the right things.”

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