PSR supports not positing too few explanatory factors, while the razor supports not positing too many. The two principles complement each other. Disproportionately associated with German rationalist philosophers Gottfried Wilhelm von Leibniz (1646–1716) and Christian Wolff (1679–1754), it appears also in the writings of Plato, Aristotle, Thomas Aquinas, and German philosopher Arthur Schopenhauer (1788–1860). The principle of sufficient reason (PSR) claims that everything has a reason or cause as to why it exists. Ockham's razor would more fairly be called “Aristotle's razor.” Rather carelessly disregarding the actual history of the principle, Scottish philosopher Sir William Hamilton (1788–1856) coined the term “Ockham's razor” in 1852, though Hamilton did not give credit where credit is due. This version has not been found in any text earlier than the 1639 commentary on Duns Scotus by Irish Franciscan theologian John Ponce of Cork (1603–1670). Its most common formulation, “Entities are not to be multiplied without necessity,” is attributed to Ockham but does not appear in any of his surviving works. Ockham wrote several statements of the principle. The French Franciscan Archbishop of Rouen, Odo Rigaldus (1205–1275), wrote in Commentary on Sentences that to posit many entities when we could posit only one is vain.

The principle is also found in the texts of Scottish Franciscan philosopher John Duns Scotus (1266–1308), who may have been Ockham's teacher. Moreover, he continued, if there are two or more metaphysical theories of a thing, at most only one of them could be correct. Thomas Aquinas (c.1225–1274), notably in Summa Contra Gentiles, in which he argues that because nature does not use two means when one would suffice, we generate superfluity if we perform any task in several ways when we could do it in one way. Like most Aristotelian ideas, it appears in the writings of Italian Dominican philosopher St. The principle of parsimony was familiar in medieval scholastic philosophy before Ockham's birth. Aristotle's counterargument was that things are substances, and there is no reason to understand any substance as existing doubly, as both itself and its idea, when it could just as well be understood as existing singly. In Book Alpha Major of the Metaphysics he refutes his teacher Plato's (c.427–c.347 BC) view that each thing on Earth has an ideal form in a supraterrestrial, intelligible realm. In Physics he asserts that the universe has only one mover. Greek philosopher Aristotle (384–322 BC) wrote in De Caelo that assumptions should be as few as possible, consistent with the known facts. Historical Background and Scientific Foundations

By going against religious dogma and positing a heliocentric system, Copernicus was able to explain these motions with a relatively uncomplicated arrangement of ellipses. Before his time, the prevailing geocentric view of the universe was bolstered by notions of epicycles and other fanciful mathematical fabrications that “explained” retrograde planetary and lunar motions. Probably the best example of the razor working to improve scientific understanding is the cosmological revolution wrought by Polish astronomer Nicolaus Copernicus (1473–1543). Ockham's razor has been the key principle of scientific method since the beginning of modern empiricism in the experiments of English polymath Francis Bacon (1561–1626) and especially since the standardization of the speculative-empirical cycle (observe, create hypothesis, test hypothesis, observe) in the twentieth century. Though scientists more commonly call it Ockham's razor, it is properly called either the principle of parsimony or the principle of economy, because it shaves away superfluous concepts. The best known version of the principle is attributed to English Franciscan nominalist philosopher William of Ockham (or Occam) (c.1288–1347). This principle has been known, practiced, and codified since ancient times. Both understanding and communication are facilitated by keeping concepts and the words that express them as simple as possible without sacrificing accuracy or completeness. Simplicity is a virtue in any explanation or description. Science Philosophy and Practice: Ockham's Razor Introduction

Ockham razor meaning