Digital Companion to C. S. Peirce
1902 | Logic (exact) | DPP 2:25; CP 3.621
… the essential office of the copula is to express a relation of a general term or terms to the universe. The universe must be well known and mutually known to be known and agreed to exist, in some sense, between speaker and hearer, between the mind as appealing to its own further consideration and the mind as so appealed to, or there can be no communication, or “common ground,” at all. The universe is, thus, not a mere concept, but is the most real of experiences.
‘Common Ground’. 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/common-ground, 09.06.2023.