Editing Occam's razor (section)

=== Formulations before William of Ockham ===
[[File:Pluralitas.jpg|thumb|Part of a page from [[John Duns Scotus]]'s book ''Commentaria oxoniensia ad IV libros magistri Sententiarus'', showing the words: "{{lang|la|Pluralitas non est ponenda sine necessitate}}", i.e., "Plurality is not to be posited without necessity"]]

The origins of what has come to be known as Occam's razor are traceable to the works of earlier philosophers such as [[John Duns Scotus]] (1265–1308), [[Robert Grosseteste]] (1175–1253), [[Maimonides]] (Moses ben-Maimon, 1138–1204), and even [[Aristotle]] (384–322&nbsp;BC).<ref>Aristotle, ''Physics'' 189a15, ''On the Heavens'' 271a33. See also Franklin, ''op cit''. note 44 to chap. 9.</ref><ref>{{Cite journal |last=Charlesworth |first=M. J. |year=1956 |title=Aristotle's Razor |journal=Philosophical Studies |volume=6 |pages=105–112 | doi=10.5840/philstudies1956606}}</ref> Aristotle writes in his ''[[Posterior Analytics]]'', "We may assume the superiority {{lang|la|ceteris paribus}} [other things being equal] of the demonstration which derives from fewer postulates or hypotheses." [[Ptolemy]] ({{nowrap|{{Circa |AD 90|168}}}}) stated, "We consider it a good principle to explain the phenomena by the simplest hypothesis possible."<ref name="Franklin">{{Cite book |title=The Science of Conjecture: Evidence and Probability before Pascal |last=Franklin |first=James |publisher=The Johns Hopkins University Press |year=2001 |author-link=James Franklin (philosopher)}} Chap 9. p.&nbsp;241.</ref>

Phrases such as "It is vain to do with more what can be done with fewer" and "A plurality is not to be posited without necessity" were commonplace in 13th-century [[Scholasticism|scholastic]] writing.<ref name="Franklin" /> Robert Grosseteste, in ''Commentary on'' [Aristotle's] ''the Posterior Analytics Books'' (''Commentarius in Posteriorum Analyticorum Libros'') ({{Circa|1217–1220}}), declares: "That is better and more valuable which requires fewer, other circumstances being equal... For if one thing were demonstrated from many and another thing from fewer equally known premises, clearly that is better which is from fewer because it makes us know quickly, just as a universal demonstration is better than particular because it produces knowledge from fewer premises. Similarly in natural science, in moral science, and in metaphysics the best is that which needs no premises and the better that which needs the fewer, other circumstances being equal."<ref>[[Alistair Cameron Crombie]], ''Robert Grosseteste and the Origins of Experimental Science 1100–1700'' (1953) pp. 85–86</ref>

The ''[[Summa Theologica]]'' of [[Thomas Aquinas]] (1225–1274) states that "it is superfluous to suppose that what can be accounted for by a few principles has been produced by many." Aquinas uses this principle to construct an objection to [[God's existence]], an objection that he in turn answers and refutes generally (cf. ''[[quinque viae]]''), and specifically, through an argument based on [[causality]].<ref>{{Cite web |url=http://www.newadvent.org/summa/1002.htm#article3 |title=SUMMA THEOLOGICA: The existence of God (Prima Pars, Q. 2) |publisher=Newadvent.org |url-status=live |archive-url=https://web.archive.org/web/20130428053715/http://www.newadvent.org/summa/1002.htm#article3 |archive-date=28 April 2013 |access-date=26 March 2013}}</ref> Hence, Aquinas acknowledges the principle that today is known as Occam's razor, but prefers causal explanations to other simple explanations (cf. also [[Correlation does not imply causation]]).