 Call the properties that are classified as intrinsic by (4) interior properties, and call the properties that are classified as non-intrinsic by (4) exterior properties. An important question is what meaning ‘in virtue’ is meant to have in (4). One possible answer is that it is meant to have a reading corresponding to metaphysical grounding, where metaphysical grounding is a non-causal explanatory relation on states of affairs, such that, if one state of affairs metaphysically grounds another state of affairs then it metaphysically necessitates it. Under such a reading of ‘in virtue’, (5) is necessarily true. 