Shepherd’s philosophy centers on her rejection of Hume’s arguments against the demonstrability of causal principles. According to Shepherd, the causal maxim—everything that begins to exist must have a cause—is demonstratively true. She begins her first major philosophical work with a proof of this maxim. While scholars have complained that the proof seems blatantly circular, a closer look at Shepherd’s texts and their Lockean background dispels this worry. Shepherd’s premises are motivated not by the causal maxim or her theory of causation, (...) but by a metaphysics that distinguishes between substances and affections and by an empirical understanding of a ‘beginning of existence.’. (shrink)