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’


Every time a man really reasons, in that sense, he is clearly or obscurely conscious that his present inference belongs to a general class of cases in which an analogous conclusion might be drawn; and his approval of this reasoning consists in a belief that by acting on the same principle in all cases he will on the whole be advancing his knowledge more than by not drawing such conclusions. If this be true, as the reader’s self-observation may satisfy him that it is, a man cannot truly reason without having some notions about the classification of arguments. But 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.

HP 2:891-892
‘Logica Utens’ (pub. 31.01.13-20:21). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Jan 31, 2013, 20:21 by Sami Paavola
Last revised: 
Jan 07, 2014, 01:00 by Commens Admin