Steven Diggin

This paper argues that ethical propositions can legitimately be used as evidence for and against empirical conclusions. Specifically, I argue that this thesis is entailed by several uncontroversial assumptions about ethical metaphysics and epistemology. I also outline several examples of ethical-to-empirical inferences where it is extremely plausible that one can rationally rely upon their ethical evidence in order to gain a justified belief in an empirical conclusion. The main upshot is that ethical propositions can, under perfectly standard conditions, play both direct and indirect evidential roles in (social) scientific inquiry.

Plausible probabilistic accounts of evidential support entail that every true proposition is evidence for itself. This paper defends this surprising principle against a series of recent objections from Jessica Brown. Specifically, the paper argues that: (i) explanationist accounts of evidential support convergently entail that every true proposition is self-evident, and (ii) it is often felicitous to cite a true proposition as evidence for itself, just not under that description. The paper also develops an objection involving the apparent impossibility of believing P on the evidential basis of P itself, but gives a reason not to be too worried about this objection. Establishing that every true proposition is self-evident saves probabilistic accounts of evidential support from absurdity, paves the way for a non-sceptical infallibilist theory of knowledge and has distinctive practical consequences.