 First, ethics. In Plato’s Euthyphro, the eponymous Euthyphro is asked by Socrates to consider the following question: Is that which is pious loved by the gods because it is pious, or is it pious because it is loved by the gods? (Euthyphro 10a). This is a very early example of a request for a metaphysical explanation, for the connection between piety and being loved by the gods imagined in the second horn does not seem to be a causal connection, but a constitutive one (although what Plato means by “because” in the first horn, and the overall structure of Plato’s argument, remains controversial). Requests for explanation abound in moral philosophy: one of the key aims of first-order moral philosophy is to explain why the right actions are right and the wrong ones are wrong (Fogal &amp; Risberg 2020), and of metaethics is to systematize those explanations. Fine (2012: 37) distinguishes between three different explanatory relations: metaphysical, normative, and natural, apparently suggesting that normative explanations and metaphysical explanations are different kinds of explanation. However, explanations in the moral realm (e.g., that an action is bad because it causes pain, or that something has intrinsic value just in case it is valuable in virtue of its intrinsic properties) are often considered paradigm cases of metaphysical explanations. Berker (2018), who is a unionist, argues at length that it is metaphysical grounding (and thus metaphysical explanation) that is at issue in moral philosophy.