The noun logic, as it is known today, first entered the English language in 1362 by William Langland in its Middle English form logyk. According to the Oxford English Dictionary, logic is “a formal system using symbolic techniques and mathematical methods to establish truth-values in the physical sciences, in language, and in philosophical argument.” In layman's terms it is the art of reasoning.1 The roots of this word trace back to ancient Greece, where it was employed by Greek stoics and philosophers such as Aristotle. In ancient Greece, what is now logic (logos) described reasoning as pertaining to discussions and speech; however it no longer has these same connotations today.2
Logos comes from the prefix of the Greek word legein, meaning to say and was a term used by Greek philosophers in metaphysical and theological work.2 Logos appeared in Aristotle's work, Aristotle's Rhetoric, which stated that there are only three forms of reason in an argument. The first was ēthos, which referred to the speaker's credibility. The second was logos, which referred to the logical argument presented. The third was pathos, which referred to the emotional effect on the audience.3
Logos evolved into logiki, which also pertained to reasoning and logiki became logica, a word used in the Middle Ages.1 In the Middle Ages, logica was an area of study in schools. The curriculum consisted of the seven liberal arts that were branched into two categories: the trivium and quadrivium. The trivium consisted of grammar, rhetoric and logica; however logica was later renamed dialectic. The quadrivium consisted of the four mathematical sciences: arithmetic, astronomy, geometry and music.4 The division between the trivium and quadrivium suggests a division between mathematics and linguistics, which reinforces the fact that even in the Middle Ages, logic (or logica) pertained more to speech. Today however, the term is associated with mathematics, sciences and computing – the mathematical side.
Logica evolved into the Old French word logique, before entering Middle English as the word logic is known today. Some forms the word logic has taken as it evolved through Middle English into Modern English include logyk and logik.1
Logos also gave the English language the -ology suffix. While some words with this ending are exceptions, the suffix in many words does derive from logos. Logos became logie in French and eventually English adopted it in the form of a suffix -logy, which became the -ology suffix.5
Logic used to mean to speak in ancient Greece, but over the centuries it has been associated more with reasoning and has lost some connotations with speech, remaining as a system of reasoning. Logic is currently associated with reasoning for actions and decision making, often a thought process, not verbalized. It pertains more to mathematics and sciences, where logic used in problem solving.
1 "logic, n.". OED Online. September 2012. Oxford University Press. http://www.oed.com/view/Entry/109788?rskey=ScN5TW&result=1&isAdvanced=false (accessed November 17, 2012).
2 "Logos, n.". OED Online. September 2012. Oxford University Press. http://www.oed.com/view/Entry/109857?redirectedFrom=logos (accessed November 17, 2012).
3 Schiappa, Edward. "Rhetoric, Greek." In The Oxford Encyclopedia of Ancient Greece and Rome, Oxford University Press. (, n.d.). Retrieved 17 Nov. 2012, from http://www.oxfordreference.com.proxy.lib.uwaterloo.ca/view/10.1093/acref/9780195170726.001.0001/acref-9780195170726-e-1093
4 Copeland, Rita. "Trivium." In Encyclopedia of Rhetoric, Oxford University Press. (, n.d.). Retrieved 17 Nov. 2012, from http://www.oxfordreference.com.proxy.lib.uwaterloo.ca/view/10.1093/acref/9780195125955.001.0001/acref-9780195125955-e-253
5 "-logy, comb. form". OED Online. September 2012. Oxford University Press. http://www.oed.com/view/Entry/109868?rskey=MLRk58&result=2&isAdvanced=false (accessed November 17, 2012).