Antirealism and the conditional fallacy: the semantic approach

The expression conditional fallacy identies a family of arguments
deemed to entail odd and false consequences for notions dened in terms of counterfactuals. The antirealist notion of truth is typically dened in terms of what a rational enquirer or a community of rational enquirers would believe if they were suitably informed. This notion is deemed to entail, via the conditional fallacy, odd and false propositions, for example that there exists necessarily a rational enquirer. If these consequences followed from the antirealist notion of truth, alethic antirealism should probably be rejected. In this paper we analyse the conditional fallacy from a semantic (i.e. model-theoretic) point of view. This allows us to identify with precision the philosophical commitments that ground the validity of this type of arguments. We show that the conditional fallacy arguments against alethic antirealism are valid only if controversial metaphysical assumptions are accepted. We suggest that the antirealist is not committed to the conditional fallacy because she is not committed to some of these assumptions.