The Commens Dictionary

Quote from ‘Letters to Paul Carus’


… the division of the elementary kinds of reasoning into three heads was made by me in my first lectures and was published in 1869 in Harris’s Journal of Speculative Philosophy. I still consider that it had a sound basis. Only in almost everything I printed before the beginning of this century I more or less mixed up Hypothesis and Induction … .

The general body of logicians had also at all times come very near recognizing the trichotomy. They only failed to do so by having so narrow and formalistic a conception of inference ( as necessarily having formulated judgments for its premises) that they did not recognize Hypothesis (or, as I now term it, retroduction) as an inference … .

1910 [c.]
CP 8.227-228
‘Hypothesis [as a form of reasoning]’ (pub. 03.02.13-17:59). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Feb 03, 2013, 17:59 by Sami Paavola
Last revised: 
Jan 02, 2016, 16:14 by Mats Bergman