Belief aims at the truth

Chapter 3 presents the alethic justification for probabilism, grounding degrees of belief in accuracy rather than action. Joyce's accuracy-dominance argument shows non-probabilistic credences are “inadmissible”—guaranteed less accurate than some probabilistic alternative in every possible world, measured by proper scoring rules like the Brier score. Easwaran addresses major challenges: credence-state dependence, the “separateness of propositions” objection, propriety requirements, and voluntarism concerns. He defends propriety through Lindley's theorem, showing any differentiable inaccuracy measure transforms uniquely into a proper scoring rule. Key discussions include purely alethic subjects (neural networks trained on classification), distinctions between alethic and evidential roles, and reciprocal grounding—showing how pragmatic agents can instrumentally value accuracy and alethic subjects can rationalize preferences. This bidirectional grounding demonstrates both roles genuinely capture doxastic normativity.