Mental causation is one of the most discussed topics in the philosophy of mind. The well-known exclusion problem is, however, often confused with a different problem called the qua problem. Contrary to conventional wisdom, Davidson's anomalous monism does not suffer from the exclusion problem, although it may seem to engender the qua problem. That is, a given mental event can be causally related to the effect to be explained (ruling out the exclusion problem). But it won't be related in virtue of its mental properties. It won't be related qua mental. The critics of anomalous monism say the mental event c is a cause of the effect e. But, the critics ask, in virtue of what is c a cause of e? This question, I argue, contains an unnoticed equivocation. There is an ambiguity in the critics' formulation of the qua problem. There are in fact two different in virtue of questions, one epistemological and one metaphysical, which are confused in the literature. I review some of the relevant parts of the philosophical literature on mental causation, causation and causal laws. And then after surveying the interpretative debate about what the historical Hume really said, I put forth my own view on the disambiguated metaphysical in virtue of question. The Reverse view, as I call it, answers a Euthyphro question about causes and laws in a novel, quasi-Humean way.