Quoted Text

Ockham’s razor
philosophy
also spelled Occam’s razor, also called law of economy, or law of parsimony, Main
principle stated by William of Ockham (1285–1347/49), a scholastic, that Pluralitas non est ponenda sine necessitate; “Plurality should not be posited without necessity.” The principle gives precedence to simplicity; of two competing theories, the simplest explanation of an entity is to be preferred. The principle is also expressed “Entities are not to be multiplied beyond necessity.”


The principle was, in fact, invoked before Ockham by Durand de Saint-Pourçain, a French Dominican theologian and philosopher of dubious orthodoxy, who used it to explain that abstraction is the apprehension of some real entity, such as an Aristotelian cognitive species, an active intellect, or a disposition, all of which he spurned as unnecessary. Likewise, in science, Nicole d’Oresme, a 14th-century French physicist, invoked the law of economy, as did Galileo later, in defending the simplest hypothesis of the heavens. Other later scientists stated similar simplifying laws and principles.

Ockham, however, mentioned the principle so frequently and employed it so sharply that it was called “Ockham’s razor.” He used it, for instance, to dispense with relations, which he held to be nothing distinct from their foundation in things; with efficient causality, which he tended to view merely as regular succession; with motion, which is merely the reappearance of a thing in a different place; with psychological powers distinct for each mode of sense; and with the presence of ideas in the mind of the Creator, which are merely the creatures themselves.

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history of philosophy ( in philosophy, Western: William of Ockham )
...is that a plurality is not to be posited without necessity. This principle of economy of thought, later stated as “beings are not to be multiplied without necessity,” is called “Ockham’s razor.”

use by Ockham ( in Ockham, William of: Early life )
...and is already profusely demonstrated in the creation of nature. The medieval rule of economy, that “plurality should not be assumed without necessity,” has come to be known as “Ockham’s razor”; the principle was used by Ockham to eliminate many entities that had been devised, especially by the scholastic philosophers, to explain reality.

use in foundations of mathematics ( in mathematics, foundations of: Set theoretic beginnings )
For some time, logicians were obsessed with a principle of parsimony, called Ockham’s razor, which justified them in reducing the number of these fundamental concepts, for example, by defining p ⊃ q (read p implies q) as ¬p ∨ q or even as ¬(p ∧ ¬q). While this definition, even if unnecessarily cumbersome, is...