Several philosophers have tried to resolve Carroll's paradox. Bertrand Russell discussed the paradox briefly in § 38 of "The Principles of Mathematics" (1903), distinguishing between "implication" (associated with the form "if "p", then "q""), which he held to be a relation between "unasserted" propositions, and "inference" (associated with the form ""p", therefore "q""), which he held to be a relation between "asserted" propositions; having made this distinction, Russell could deny that the Tortoise's attempt to treat "inferring" "Z" from "A" and "B" as equivalent to, or dependent on, agreeing to the "hypothetical" "If "A" and "B" are true, then "Z" is true."