The Objectivism Boundary — agreement is ontological (hypothetical oughts, no unchosen duties); the seam is life-vs-action, man qua man, the analytic/synthetic rejection, and egoism vs. EGT
Philippa Foot — Natural Goodness, Read Against the Vault — sourced (SEP + 1967 primary): functional core without essence; she abandoned the hypothetical-imperative view the vault holds; Sheriff ≠ trolley; not “what survives”