In a methodological milieu characterized by efforts to bring the methods of philosophy closer to the methods of the sciences, one can find, with increasing regularity, meta-ethical arguments relying on scientific theory or data. The received view appears to be that, not only is it implausible to think that a scientific vindication of a non-mentalist moral semantics will be forthcoming but that evidence from a variety of sciences threatens to undermine non-mentalist views. My aim is to push back against this (...) apparent consensus. The well-established phenomenon whereby moral judgments influence our attributions of putatively purely descriptive properties has come to be known as the Knobe Effect. Joshua Knobe has attempted to explain this surprising phenomenon by arguing that our folk psychological judgments are partially constituted by moral judgments. Drawing on an argument originally offered by Moore, I argue that if some instantiation of Knobe’s explanatory strategy is accurate, we have good reason to believe that mentalist moral semantics are untenable. (shrink)