Certainty

Certainty, in its strong sense, means an idea is guaranteed error-proof: 100% certain, beyond any possibility of revision. CF, following fallibilism, denies that this is ever available. No matter how confident we feel or how carefully we double-check, we could have missed something, so we cannot get 100% certain proof of anything. This rejects infallibilism and the justificationist project of accumulating support to make an idea true or “less fallible.”

Crucially, CF denies certainty without sliding into skepticism. Being unable to be certain does not mean any particular idea is wrong, only that you stay open to correction; ideas are held with tentativity. You can still reach confident conclusions and act decisively.

CF’s distinctive move is to reject the replacement for certainty offered by most fallibilists: degrees of certainty, credences, or probabilities of ideas. Outside genuine statistical cases (dice, measurement), certainty numbers are basically made up — there is no way to determine that you are 90% rather than 80% certain — and assigning a certainty to every idea triggers an infinite regress, since each certainty judgment is itself an idea needing its own certainty. Instead, binary judgment asks only whether you know of a non-refuted criticism of an idea.

Where Objectivism speaks of “certainty” as a kind of contextual knowledge, CF prefers terms like proper or conclusive knowledge, since “certainty” sounds infallibilist.