The Commens Dictionary

Quote from ‘Harvard Lectures on the Logic of Science. Lecture X: Grounds of Induction’


But the manner in which they have attained to certainty indicates a very different general strength of the three kinds of inference. [—] Thus we have in order of strength Deduction, Induction, Hypothesis. Deduction, in fact, is the only demonstration; yet no one thinks of questioning a good induction, while hypothesis is proverbially dangerous. Hypotheses non fingo, said Newton, striving to place his theory on a basis of strict induction. Yet it is hypotheses with which we must start; the baby when he lies turning his fingers before his eyes is making a hypothesis as to the connection of what he sees and what he feels. Hypotheses give us our facts. Induction extends our knowledge. Deduction makes it distinct.

W 1:283
‘Hypothesis [as a form of reasoning]’ (pub. 02.02.13-17:12). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Feb 02, 2013, 17:12 by Sami Paavola
Last revised: 
Jan 07, 2014, 01:00 by Commens Admin