The Commens Dictionary

Quote from ‘Letters to Lady Welby’


I now come to Thirdness. To me, who have for forty years considered the matter from every point of view that I could discover, the inadequacy of Secondness to cover all that is in our minds is so evident that I scarce know how to begin to persuade any person of it who is not already convinced of it. Yet I see a great many thinkers who are trying to construct a system without putting any thirdness into it. Among them are some of my best friends who acknowledge themselves indebted to me for ideas but have never learned the principal lesson. Very well. It is highly proper that Secondness should be searched to its very bottom. Thus only can the indispensableness and irreducibility of thirdness be made out, although for him who has the mind to grasp it, it is sufficient to say that no branching of a line can result from putting one line on the end of another. My friend Schröder fell in love with my algebra of dyadic relations. The few pages I gave to it in my Note B in the ‘Studies in Logic by Members of the Johns Hopkins University’ were proportionate to its importance. His book is profound, but its profundity only makes it more clear that Secondness cannot compass Thirdness. (He is careful to avoid ever saying that it can, but he does go so far as to say that Secondness is the more important. So it is, considering that Thirdness cannot be understood without Secondness. But as to its application, it is so inferior to Thirdness as to be in that aspect quite in a different world.) Even in the most degenerate form of Thirdness, and thirdness has two grades of degeneracy, something may be detected which is not mere secondness. If you take any ordinary triadic relation, you will always find a mental element in it. Brute action is secondness, any mentality involves thirdness. Analyze for instance the relation involved in ‘A gives B to C.’ Now what is giving? It does not consist [in] A’s putting B away from him and C’s subsequently taking B up. It is not necessary that any material transfer should take place. It consists in A’s making C the possessor according to Law. There must be some kind of law before there can be any kind of giving, – be it but the law of the strongest. But now suppose that giving did consist merely in A’s laying down the B which C subsequently picks up. That would be a degenerate form of Thirdness in which the thirdness is externally appended. In A’s putting away B, there is no thirdness. In C’s taking B, there is no thirdness. But if you say that these two acts constitute a single operation by virtue of the identity of the B, you transcend the mere brute fact, you introduce a mental element [—]

I have not sufficiently applied myself to the study of the degenerate forms of Thirdness, though I think I see that it has two distinct grades of degeneracy. In its genuine form, Thirdness is the triadic relation existing between a sign, its object, and the interpreting thought, itself a sign, considered as constituting the mode of being of a sign.

CP 8.331-332
‘Thirdness’ (pub. 09.03.13-15:14). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from
Mar 09, 2013, 15:14 by Sami Paavola
Last revised: 
Jan 07, 2014, 00:58 by Commens Admin