logue of etion wanderments

Occam’s Razor

Occam’s razor (or the law of parsimony or of economy) is one of the most outrageously abused principles in contemporary rhetoric. The principle that says that explanations should be as simple as possible: “Pluralitas non est ponenda sine neccesitate” or “plurality should not be posited without necessity.” Today it means selecting among the competing hypothesis the one that makes the least number of new assumptions, if the hypotheses are otherwise equal … for instance, they (the hypothesis) must account for all available data.

Occam’s razor is NOT considered an irrefutable principle of logic, and certainly NOT a scientific result. It is used as a heuristic (general guiding rule) to guide scientists for developing theoretical models. {Even though Marcus Hutter has shown mathematically that short computable theories have more weight when calculating the expected value of an action across all computable theories which perfectly describe previous observations.}

All justifications for Occam’s Razor ultimately point to convenience of using theories left after Occam’s Razor has been used:

  1. Aesthetically, simpler things are better to work with.
  2. Empirical content of simpler theories is greater and hence they are better testable.
  3. Simpler theories require less information to answer the same questions, hence are more informative.

Weaknesses: It fails as a criteria of prediction. Evidence doesn’t seem noticeably supporting Occam’s razor. In fact, anti-razors have been proposed, more than once (e.g., if three things don’t explain something then add a fourth).


  1. In reducing number of competing theories while explaining some phenomena.
  2. Reportedly, the Razor has been occasionally distorted to support argument for ‘budget cuts’ arguing that “what can be done with less is done in vain with more.” … conveniently forgetting the word assumptions.

Many pragmatic philosophers, like Einstein, have cautioned against over-use of the Razor.

One of the more palatable forms of Occam’s Razor is due to Ayn Rand: “Concepts are not to be multiplied beyond necessity—the corollary of which is: nor are they to be integrated in disregard of necessity.”

References not linked above:


2 responses to “Occam’s Razor

  1. epanechnikov February 14, 2011 at 21:05

    Dear αιτιολόγε

    The Occam’s razor corresponds to the Popper’s degrees of falsifiability and to the idea of simplicity. It is definitely not established as a result of formal logic but I believe it makes sense. “Every ‘good’ scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.”

    • etio July 13, 2011 at 15:44

      It borrows from economical sense and is supposed to be use only when the two alternative explanations are otherwise equal.

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