Occam’s Razor (Ockham’s Razor) is also known as the Law of Economy, the Law of Parsimony, or the Principle of Parsimony. It says “entities are not to be multiplied beyond necessity” ( Entia non sunt multiplicanda praeter necessitatem ). Another form of the principle is “plurality should not be posited without necessity” ( Pluralitas non est ponenda sine necessitate ).
The principle claims that to explain something, all competing explanations should be “shaved” away until only the simplest remains. When applied to the construction of theories explaining a phenomenon in the event that competing hypotheses provide contradictory explanations, the one that uses the least theoretical assumptions is probably the more accurate. If a detective is reconstructing the facts of a murder, the “theory” of the crime will be the one that best fits the facts and is usually the simplest hypothesis. This principle agrees with the philosophy of science’s understanding that nature’s character is simple.
The idea of parsimonious simplicity is found in limited form in the works of Aristotle. It was championed by William of Ockham (c. 1280–1349), after whom the term “Occam’s Razor” was named. It was also used by Galileo Galilee (1564–1642) when discussing the data describing the orbits of the planets in support of the Copernican model.
Opponents of Occam’s razor proposed antirazors which say where fewer entities do not suffice, posit more. For example, in biblical textual analysis, if a scholar is faced with variant readings from different manuscripts the problem is which variant is the one closest to the original autograph of the biblical writer? The general rule, in the absence of evidence to the contrary, is to choose the more complicated reading. The reason is that a few scribes and others who copied the thousands of surviving manuscripts sometimes tried to “correct” an apparently unclear, complicated reading by “simplifying” it.
Occam’s razor is used in philosophy, learning theory, econometrics, public policy choices and other disciplines. In public policy choices the principle is used by analysts to show that self-interest motivates voters and that the desire for reelection motives legislators, both of which are the simplest explanations for voter and legislator behavior.
Econometrics uses Occam’s razor in labor economics, financial operations studies, resource allocations, and other areas as an aided method for discovery, problem solving, or learning. It is applied as the principle that what works well and is simple will probably work best in decisions concerning poverty funding for the developing world.
Currently Occam’s razor is a characteristic of alife (artificial life) studies of ecological systems. Alife uses computers, simulations and other techniques in an information systems “bottom up” approach to study the ecology associated with living organisms and how they interact with their environment.
Some anti-razorists reject Occam’s razor as inadequate to explain complicated phenomena. The facts of experience tell them that a complicated model may require a complicated explanation, while at other times simplicity is the most effective.
Spade, Paul Vincent, ed. 1999. The Cambridge Companion to Ockham. Cambridge, U.K.: Cambridge University Press.
Zellner, Arnold. Hugo A. Keuzenkamp, and Michael McAleer, eds. 2001. Simplicity, Inference and Modeling: Keeping it Sophisticatedly Simple. Cambridge, U.K.: Cambridge University Press.
Andrew J. Waskey