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.
A logical principle is said to be an empty or merely formal proposition, because it can add nothing to the premisses of the argument it governs, although it is relevant; so that it implies no fact except such as is presupposed in all discourse…
W 4:167-168; CP 3.166, 168
‘Logical Principle’ (pub. 23.03.18-15:04). 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-5.