As explained in Chapter III, to reason on the ground of a particular proposition some S is P is a precarious procedure in which the introduction of the instantiated term must be done "critically" (III-2). The "formalization" or algorithmic description of the rules that justify arguments with such premisses has finally become a reality due to the work of Frege. Altogether we have now more than enough reasons to focus our attention, in our search for the logic of indefinite terms, upon traditional treatments of particular propositions, and especially upon the import and use of particular premisses. Let us start with a brief survey of some influential opinions throughout the centuries.