The Commens Dictionary
Quote from ‘On the Algebra of Logic’
…a leading principle, which contains no fact not implied or observable in the premisses, is termed a logical principle, and the argument it governs is termed a complete, in contradistinction to an incomplete, argument, or enthymeme.
We may here distinguish between logical and extralogical validity; the former being that of a complete, the latter that of an incomplete argument.
W 4:167-168; CP 3.166, 168
‘Logical Validity’ (pub. 23.03.18-15:13). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from http://www.commens.org/dictionary/entry/quote-algebra-logic-7.