Rozeboom Rozeboom

In a recent note, Horwich challenges the foundations of Hempel's classic paradox of confirmation by a clever example purporting to show that under Nicod's Criterion, data can be made to confirm a hypothesis with which they are logically incompatible. Specifically, Horwich observes that 'Pb' is formally equivalent to ''. The latter has form '' with '∼P___ · ∼Pb' for 'Ψ' and '___ ≠ b' for 'ϕ', while the observation that distinct objects a and b both lack P, i.e. that —Pa · ∼Pb · a ≠ b, can be expressed as 'Ψa · ϕa' for these same instantiations of the predicate markers. Accordingly, if an uncertain generality '' were always to be confirmed by an observation of form 'Ψa · ϕa', as Nicod's Criterion has long been presumed to say, then we could confirm that b has P by observing that b and some other object both lack P—a flagrant absurdity.