Editing De Morgan's laws (section)

==History==
The laws are named after [[Augustus De Morgan]] (1806–1871),<ref>{{cite web |url=http://www.mtsu.edu/~phys2020/Lectures/L19-L25/L3/DeMorgan/body_demorgan.html |title=DeMorgan's Theorems |archive-url=https://web.archive.org/web/20080323122125/http://www.mtsu.edu/~phys2020/Lectures/L19-L25/L3/DeMorgan/body_demorgan.html |archive-date=2008-03-23 |publisher=[[Middle Tennessee State University]] }}</ref> who introduced a formal version of the laws to classical [[propositional logic]]. De Morgan's formulation was influenced by the algebraization of logic undertaken by [[George Boole]], which later cemented De Morgan's claim to the find. Nevertheless, a similar observation was made by [[Aristotle]], and was known to Greek and Medieval logicians.<ref>{{cite book |title=A History of Formal Logic |last=Bocheński |first=I. M. |date=1961 |url=https://archive.org/details/historyofformall00boch/page/207 |location=Notre Dame, Indiana |publisher=[[University of Notre Dame Press]] |page=207 |lccn=58014183 |author-link=Józef Maria Bocheński}}</ref> For example, in the 14th century, [[William of Ockham]] wrote down the words that would result by reading the laws out.<ref>William of Ockham, ''Summa Logicae'', part II, sections 32 and 33.</ref> [[Jean Buridan]], in his {{lang|la|Summulae de Dialectica}}, also describes rules of conversion that follow the lines of De Morgan's laws.<ref>Jean Buridan, ''Summula de Dialectica''. Trans. Gyula Klima. New Haven: Yale University Press, 2001. See especially Treatise 1, Chapter 7, Section 5. {{ISBN|0-300-08425-0}}</ref> Still, De Morgan is given credit for stating the laws in the terms of modern formal logic, and incorporating them into the language of logic. De Morgan's laws can be proved easily, and may even seem trivial.<ref>{{cite web |url=http://www.engr.iupui.edu/~orr/webpages/cpt120/mathbios/ademo.htm |title=Augustus De Morgan (1806–1871) |archive-url=https://web.archive.org/web/20100715185655/http://www.engr.iupui.edu/~orr/webpages/cpt120/mathbios/ademo.htm |archive-date=2010-07-15 |author=Robert H. Orr |publisher=[[Indiana University–Purdue University Indianapolis]] }}</ref> Nonetheless, these laws are helpful in making valid inferences in proofs and deductive arguments.