Occam's Razor

Occam's razor.It's January in the northern hemisphere and you are suffering elevated body temperature, muscle aches, a cough, and a runny nose. Would it be more likely that you are suffering from the common cold or that you are simultaneously suffering from heat stroke, fibromyalgia, pneumonia, and hay fever? Obviously, the single unifying, parsimonious explanation is a far more acceptable answer.

William of Ockham (~1285–1349) was a Franciscan friar best remembered for the heuristic maxim that translates as "entities should not be multiplied beyond necessity" (entia non sunt multiplicanda praeter necessitatem).

Occam's razor (or Ockham's razor) holds that one should always accept as most-likely the most economical explanation that accounts for all the facts. However, Occam's razor is not to be interpreted as suggesting that the simplest or most easily conceived mechanism is explanatory.

(Semiotician Umberto Eco alludes to William of Ockham in his protagonist in "The Name of the Rose".)

Bookcover for Umberto Eco's The Name of the RoseWhile the common cold would be a better explanation for those diverse symptoms, as many as 200 different "common cold" viruses could cause these symptoms, as could influenza. So, applying the razor does not provide the specific answer, but rather eliminates cumbersome alternative hypotheses.

Why should we prefer the common cold/influenza explanation? In January in the northern hemisphere, the incidence of the common cold might reach one in ten, whereas the incidence of heat stroke might be near zero, the prevalence of fibromyalgia one in fifty, the incidence of pneumonia one in a thousand, and the incidence of hay fever zero.

(1/10 is greater than 0 x 1/100,000 x 1/50 x 0, in other words, 1/10 is greater than 0)

For primitive man, a God of the Gaps strategy invented an oversimplified explanation of phenomena ranging from weather to illness. However, much to the chagrin of creationists, we now know that natural laws provide more accurate, though more complex, explanations for observed phenomena. In this reverse of Occam's razor–let's call it Shaving Miracles–such oversimplified, miraculous, supernatural explanations for physical phenomena do not provide any explanation at all. In other words, the probability of God is 0.

How did it happen?

It was a miracle.

How did the miracle operate?

That's for God to know.

How do we know that there is a God?

How else could the miracles have happened?

. . . no explanation at all.

Sites Elsewhere: Why The Simplest Theory Is Never The Right One: Occam's Razor Has A Double Edge : Against parsimony, again : Failures of Reductionism? Level of Analysis Problems in Cognitive Neuroscience :

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