World 3

Popper divided reality into three categories. World 1 is physical objects and states (matter, energy, brains). World 2 is subjective mental states (beliefs, sensations, experiences). World 3 is the realm of objective thought-contents: theories, arguments, problems, conjectures, and their logical relations. A proof’s validity, a contradiction between two claims, or an unsolved problem belongs to World 3 — it holds whether or not anyone currently grasps it. On Popper’s account World 3 is created by humans yet, once made, has objective features we discover rather than invent, much as the natural numbers generate prime-distribution facts no one decided. (This exposition follows the standard Popper account; CF’s own writings reference the three-worlds doctrine only in passing.)

CF (Elliot Temple’s philosophy) does not foreground the “three worlds” labels — and indeed prefers David Deutsch’s explanation-based view of the reality of abstractions to Popper’s three-worlds framing — but it depends heavily on the underlying insight that ideas have objective content standing apart from their holder. This grounds the rule, stated directly in CF, that ideas are judged by their content, not their source: not by the credentials, prestige, or popularity of whoever advances them (see content over source). It is also why CF frames refutation as targeting the idea, not the person: a criticism succeeds or fails on whether it identifies a real flaw in the argument’s content, an objective matter.

The view opposes psychologism, which would reduce logic and knowledge to World 2 mental events. It supports CF’s commitment to objective truth and to treating knowledge as criticizable public content — the precondition for genuine error correction and rational debate rather than mere clashes of opinion.