The Commens Dictionary

Quote from ‘Letter to J. H. Kehler’


Skipping a great deal, I now take up the third great class of Reasonings, which I call Retroductions. [—] By the third class of reasonings one only infers that a certain state of things may be true and that the indications of its being so are sufficient to warrant further examination. [—] The reason for accepting the Retroductive conclusion, is that man must trust to his power of getting at the truth simply because it is all he has to guide him; and moreover when we look at the instincts of various animals, we are struck with wonder at how they lead those creatures toward rational behaviour. [—]

I do not, at present, feel quite convinced that any logical form can be assigned that will cover all “Retroductions”. For what I mean by a Retroduction is simply a conjecture which arises in the mind.

NEM 3:203-204
‘Retroduction’ (pub. 12.03.13-19:10). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Mar 12, 2013, 19:10 by Sami Paavola
Last revised: 
Jan 07, 2014, 00:58 by Commens Admin