 Here substantive means apt for grounding and autonomous means not apt for grounding. For example, perhaps essentialist facts are autonomous where essentialist facts are facts of the form: it is essential to \(x\) that \(\phi\). The idea is that just as definitions are not apt for proof, essentialist facts are not apt for grounding explanations, that is, they are autonomous (Dasgupta 2016: 6–9). The notion of an autonomous fact allows the adherent of this version of the PSR to avoid the Agrippan Trilemma without allowing for self-explanatory facts or infinite regresses. Chains of explanation terminate with autonomous facts, which are not brute because they are not apt for explanation. 