The Commens Dictionary
Quote from ‘The Proper Treatment of Hypotheses: a Preliminary Chapter, toward an Examination of Hume's Argument against Miracles, in its Logic and in its History’
… the classification of arguments is the chief business of the science of logic; so that every man who reasons (in the above sense) has necessarily a rudimentary science of logic, good or bad. The slang of the medieval universities called this his logica utens, - his “logic in possession”, - in contradistinction to logica docens, or the legitimate doctrine that is to be learned by study.
‘Logica Docens’ (pub. 31.01.13-20:18). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from http://www.commens.org/dictionary/entry/quote-proper-treatment-hypotheses-preliminary-chapter-toward-examination-humes-2.