The Commens Dictionary

Quote from ‘Harvard Lectures on the Logic of Science. Lecture VIII: Forms of Induction and Hypothesis’


Hypothesis is to be explained in a similar manner to induction. Hypothesis is quite a different thing from induction and is usually so considered although I have not found any definition given of it which brings out the difference distinctly. But it will be acknowledged that a hypothesis is a categorical assertion of something we have not experienced. Now in induction there is nothing of this sort. [—] Hypothesis is in fact the inference of a minor proposition as in the following examples respecting light.

We find that light gives certain peculiar fringes. Required an explanation of the fact. We reflect that ether waves would give the same fringes. We have therefore only to suppose that light is ether waves and the marvel is explained.

We have then three different kinds of inference. Deduction or inference à priori. Induction or inference à particularis, and Hypothesis or inference a posteriori.

W 1:266-267
‘À Posteriori Reasoning’ (pub. 28.01.13-20:39). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Jan 28, 2013, 20:39 by Sami Paavola
Last revised: 
Jan 07, 2014, 01:00 by Commens Admin