Digital Companion to C. S. Peirce
1906 | The Basis of Pragmaticism | EP 2:382-283
A relation of reason is not purely dyadic: it is a relation through a sign: that is why it is dicible. Consequently the relation involved in duality is not dicible, but surd; and duality must contain as an ingredient of it a surd disquiparance.
The double relation of equiparance which constitutes duality is surd. It may be described in words, but those words can only be understood by means of reference to certain experiences; just as a person may be told that a piece of textile fabric is a yard wide, yet can never know what is meant except through an experience immediate or mediate of a certain bar laid up in the Westminster palace.
‘Duality’. Term 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/term/duality, 10.06.2023.