Occam*s razor

Occam's razor (sometimes spelled Ockham's razor) is a principle attributed to the 14th-century English logician and Franciscan friar William of Ockham. The principle states that the explanation of any phenomenon should make as few assumptions as possible, eliminating those that make no difference in the observable predictions of the explanatory hypothesis or theory. The principle is often expressed in Latin as the lex parsimoniae (""law of parsimony"" or ""law of succinctness""): ""entia non sunt multiplicanda praeter necessitatem"", or ""entities should not be multiplied beyond necessity"".

This is often paraphrased as ""All other things being equal, the simplest solution is the best."" In other words, when multiple competing theories are equal in other respects, the principle recommends selecting the theory that introduces the fewest assumptions and postulates the fewest entities. It is in this sense that Occam's razor is usually understood.

Originally a tenet of the reductionist philosophy of nominalism, it is more often taken today as a heuristic maxim (rule of thumb) that advises economy, parsimony, or simplicity, often or especially in scientific theories.

Anti-razors have also been created by Gottfried Wilhelm Leibniz (1646-1716), Immanuel Kant (1724-1804), and Karl Menger (1902-1985). Leibniz's version took the form of a principle of plenitude, as Arthur Lovejoy has called it, the idea being that God created the most varied and populous of possible worlds. Kant felt a need to moderate the effects of Occam's Razor and thus created his own counter-razor: ""The variety of beings should not rashly be diminished.""

Source: Wikipedia contributors, ""Occam's razor,"" Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Occam%27s_razor&oldid=186914085 (accessed January 28, 2008).

""A rule in science and philosophy stating that entities should not be multiplied needlessly. This rule is interpreted to mean that the simplest of two or more competing theories is preferable and that an explanation for unknown phenomena should first be attempted in terms of what is already known. Also called law of parsimony. "" (occam's razor. Dictionary.com. The American Heritage® Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. http://dictionary.reference.com/browse/occam's razor (accessed: January 28, 2008).

""the maxim that assumptions introduced to explain a thing must not be multiplied beyond necessity"" (occam's razor. Dictionary.com. Dictionary.com Unabridged (v 1.1). Random House, Inc. http://dictionary.reference.com/browse/occam's razor (accessed: January 28, 2008).