Occam's Razor

Atheists frequently invoke Occam’s razor as an argument against the existence of God. “Given two possible scenarios for the existence of the universe—creation or naturalistic evolution—Occam’s razor dictates that the simpler of the two (evolution) is to be preferred.” This argument represents a misunderstanding, a misapplication, or both, of the principle of Occam’s razor.

This principle of logic, also known as the “principle of parsimony,” has been attributed to William of Ockham (ca. 1285-1349), an English philosopher and Franciscan monk. This idea was apparently not original with him, but came from an Aristotelian concept that entities must not be multiplied beyond what is necessary. Occam’s frequent use of this idea nonetheless brought the principle to a wider audience. As originally stated, it is, “pluralitas non est ponenda sine necessitate,” which means “plurality should not be posited without necessity.”

Perhaps because of a perceived unwieldiness of the statement as given (“plurality should not be posited without necessity”), many have paraphrased this principle in various ways, such as “the simpler explanation is likely to be right.” Much is often lost in such a paraphrase, and this loss may have serious implications for the propriety of using this principle in a given context. Occam’s razor does not value simplicity as inherently better (or more likely) than complexity. Therefore, many appeals to Occam’s razor are in error because they misrepresent it in this way.

A common approach is to argue that the choice between creation and evolution boils down to a choice between one God or zero gods, and that, according to Occam’s razor, zero gods is the preferable alternative. There is, however, a clear misapplication of the principle here. Where used most appropriately, Occam’s razor establishes criteria for choosing from among theories with equal explanatory power. It is useful as an abductive argument, after all inductive arguments are compared. What I’m arguing is that if and only if two explanations—in this case the biblical creation model and the naturalistic evolution model—are equal and inseparable in their explanatory power, their logical cohesion, their empirical support, and such, and if, in addition, we have exhausted the possibility that further research will be able to separate these competing theories with regard to these criteria, are we justified in applying Occam’s razor to this important, overarching question.

The truth is that there is a great deal of scientific evidence that allows us to assess these competing models without appealing to Occam’s razor. The two theories make numerous opposite predictions that are quite testable. The naturalistic model gained respectability under the assumption—now known to be false—that the universe itself was eternal, whereas the biblical model has always asserted that the universe had a beginning. Considering the fossil record, as another example, the evolutionary model predicts that life arose once very slowly, that transitional intermediate life forms should be apparent and common, and that life forms gradually changed throughout their tenure on earth. It is the opposite predictions of the creation model—that life appeared suddenly and repeatedly, that transitional intermediates are few or non-existent, and that each life form exhibits stasis during its tenure—that are supported by the evidence. Other aspects of life that the creation model adequately explains and that the naturalistic model fails to explain include irreducibly complex systems and the information code in DNA.

While the philosophical principle known as Occam’s razor has very specific application in certain rather abstract mathematical and scientific modeling, it is simply inappropriate for assessing the explanatory scope and power of competing explanations for the existence of the universe and the existence and diversity of life.