Published online by Cambridge University Press: 24 September 2015
To evaluate the overall good/welfare of any action, policy or institutional choice we need some way of comparing the benefits and losses to those affected: we need to make interpersonal comparisons of the good/welfare. Yet sceptics have worried either: (1) that such comparisons are impossible as they involve an impossible introspection across individuals, getting ‘into their minds’; (2) that they are indeterminate as individual-level information is compatible with a range of welfare numbers; or (3) that they are metaphysically mysterious as they assume the existence either of a social mind or of absolute levels of welfare when no such things exist. This article argues that such scepticism can potentially be addressed if we view the problem of interpersonal comparisons as fundamentally an epistemic problem – that is, as a problem of forming justified beliefs about the overall good based on evidence of the individual good.
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17 I am very grateful for extremely helpful comments on this article from participants of a 2011 NYU Political Theory group meeting, a 2011 LSE Choice Group session, a 2012 Harvard-MIT special political theory seminar, and a 2015 Paris seminar in Normative Political Philosophy at the Ecole des Hautes Etudes en Sciences Sociales, and also to detailed comments from Russell Hardin, Sean Ingham, Michael Kates, Dimitri Landa, Christian List, Bernard Manin, Michael Rosen, Kai Spiekermann and Lucas Stanczyk.
18 Proof: As (h ∧ ¬h) → h therefore Cr(h ∧ ¬h) ≤ Cr(h). As h → (h v ¬h) therefore Cr(h) ≤ Cr(h v ¬h). (In fact, given Additivity, not only does Coherence entail Boundedness, but the converse is true too. Proof: As Y → ¬ (¬Y) therefore Cr(Y) + Cr(¬Y) = Cr(Y v ¬Y) [From A1]. If X → Y then Cr(X v ¬Y) = Cr(X) + Cr(¬Y) [From A1]. Thus Cr(X v ¬Y) + Cr(¬X ∧ Y) = Cr((Xv ¬Y) v (¬X ∧Y)) = Cr(Y v ¬Y). Therefore Cr(X) + Cr(¬Y) + Cr(¬X ∧ Y) = Cr(Y) + Cr(¬Y). As Cr(¬X ∧Y) ≥ 0 [From Boundedness] therefore if X → Y then Cr (Y) ≥ Cr (X) QED.)