‘You Reap What You Sow’. The Logic and History of the Reaper Argument

This paper re-examines the so-called Reaper Argument (RA), a paradox on future contingents transmitted through late Neoplatonic commentaries on Aristotle's de Interpretatione and through Cicero's philosophical writings. By comparing the testimonies of Ammonius, Stephanus, the Anonymous commentator, and Cicero, we argue that Cicero provides the earliest and most valuable witness, whose affinities with Stephanus strengthen the reliability of both against the standard priority accorded to Ammonius. On this textual basis, we reconstruct RA as a logically rigorous argument rather than a sophism, and we propose a formalization and an interpretation in terms of an ‘anchored semantics’, which should capture its internal reasoning. The analysis shows that RA does not rest on the Principle of Bivalence but on the Rule of Contradictory Pairs, and that its conclusion establishes a horizon-bound form of determinism: once a future instant is fixed, one of the two incompatible outcomes is already necessary. Finally, by situating RA within its Hellenistic context, we defend the plausibility of attributing the paradox to Diodorus Cronus.