Ketner on Percy and Peirce

To descend to more particular similarities, we might first notice that when we initially come to realize our personhood, we find that we are in a world, as Percy in Lost in the Cosmos (p. 96) phrases it, as opposed to just an environment. An environment, in his sense, is a setting in which only efficient causal relations are to be found. A world, on the other hand, along with environmental factors, also includes significance, meaning, interpretation, understanding, and selves. These additional factors Percy places under the heading of triadic behavior, or sign-use. Percy's discovery was that such triadic relations cannot be reduced to conglomerates of dyadic relations. Or, worlds are not reducible to environments. In this point Percy is actually an independent rediscoverer (see Percy's "The Delta Factor") of the almost identical principle noticed by Peirce about 1866. I have traced aspects of these two parallel discoveries elsewhere ("Peirce's 'Most Lucid and Interesting Paper': An Introduction to Cenopythagoreanism") in considerable detail.

It is a major confirmation of my thesis that Percy, after a period of intense immersion in the literature of existentialism, rediscovered this point independently. Only later did he come to realize that Peirce had worked it out almost a century earlier. That the two thinkers are so close on this fundamental point is a major confirmation, and hence perhaps the principal point of comparison that tends to support pragmaticism really being an existentialism.

-- Kenneth Ketner, in A Thief of Peirce, Appendix II: "Pragmaticism an Existentialism?" p. 291-2.