The Fall issue of JARS features a curious article entitled "Some Convergences and Divergences in the Realism of Charles Peirce and Ayn Rand." Peirce is the greatest of all American born philosophers: an extraordinarily subtle and penetrating philosopher whose complex cerebrations often take a visionary turn. Rand, who, along with William James, is the most widely read American philosopher, is also a "vision" philosopher, though her genius manifests itself in the ability to put across a vision and make it live in the hearts of her sympathetic readers rather than in creating a convincing philosophic system. The JARS article, by Marc Champagne, is a bit too subtle to get into here. Summarizing it in my own philosophic language, I would say that the greatest common denominator between Peirce and Rand is they both involved in a revolt against epistemological dualism: that is, neither of them are very comfortable with the notion that our knowledge of the world is mediated through the veil of ideas, or that it is useful to distinguish between essence and existence, between World 1 (physical reality) and World 3 (platonic Ideas or essences) objects. Where they differ, is in their strategies for evading the dualistic implications of realism. Rand's approach is largely verbal: she keeps insisting on the objectivity of concepts (as if such matters could be settled by mere assertion!) and drops hints about the horrors of Cartesian representationalism, particularly as it manifests itself in Kant's confused separation of phenomena and noumena. Peirce, a much more intellectually responsible philosopher, attempts to advance some very sophisticated metaphysical arguments to extricate himself from epistemological dualism. In the end, however, having denied the fundamental difference between reality and an individual's experience of reality, he winds up adopting something very close to idealism: he even goes so far as to suggest that "all is signs"--i.e., only World 3 objects exist.
Why are both these philosophers so down on epistemological dualism? I suspect that it derives from the fact that both Rand and Peirce believe in speculative metaphysics--i.e., they both hold that matters of fact can be determined by logical constructions. But once thoughts are distinguished from the existents in reality, speculative metaphysics, particularly of the rigorously logical variety, becomes a far less plausible undertaking. The world of Ideas (Popper's World 3 and Santayana's realm of essence) is infinite; and therefore, the number of logical combinations (or arguments) is also infinite. But only a small fraction of those infinite combinations will likely ever be found to describe something manifested in the world of matter (Popper's World 1), which means such manifestations are fortutious: there is nothing necessary about them. To find out whether a given logical combination corresponds with reality, one must look to the facts of the matter.