Sui generis
In sociology, the "sui generis" is what has been externalized, then internalized in the overall public and becomes a part of society that simply exists in its construct. It is not something that is not thought to have been created, because it is imbedded in everyone's way of thinking and being. Instances include the idea of love, or going to school, or clothing belonging to a specific gender. These examples are "sui generis" for they simply exist in society and are widely accepted without thoughts of where they come from or how they were created.
Abductive reasoning
In 1867, Peirce's "The Natural Classification of Arguments", hypothetical inference always deals with a cluster of characters (call them "P′, P′′, P′′′," etc.) known to occur at least whenever a certain character ("M") occurs. Note that categorical syllogisms have elements traditionally called middles, predicates, and subjects. For example: All "men" [middle] are "mortal" [predicate]; "Socrates" [subject] is a "man" [middle]; ergo "Socrates" [subject] is "mortal" [predicate]". Below, 'M' stands for a middle; 'P' for a predicate; 'S' for a subject. Note also that Peirce held that all deduction can be put into the form of the categorical syllogism Barbara (AAA-1).