The Commens Dictionary

Quote from ‘A Neglected Argument for the Reality of God (G)’


[Qualitative Induction] consists of those inductions which are neither founded upon experience in one mass, as Crude Induction is, nor upon a collection of numerable instances of equal evidential values, but upon a stream of experience in which the relative evidential values of different parts of it have to be estimated according to our sense of the impressions they make upon us.

Qualitative Induction consists in the investigator’s first deducing from the retroductive hypothesis as great an evidential weight of genuine conditional predictions as he can conveniently undertake to make and to bring to the test, the condition under which he asserts them being that of the retroductive hypothesis having such degree and kind of truth as to assure their truth. In calling them “predictions,” I do not mean that they need relate to future events but that they must antecede the investigator’s knowledge of their truth, or at least that they must virtually antecede it.

1908 [c.]
CP 2.759
‘Qualitative Induction’ (pub. 13.01.15-17:45). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Jan 13, 2015, 17:45 by Mats Bergman
Last revised: 
Mar 04, 2016, 12:17 by Mats Bergman