Professor Moore’s two central theses in Causing, Aiding, and the Superfluity of Accomplice Liability are, first, that we should recognize not just one, but four distinct types or “desert bases” of accomplice liability; and second, that once we have done this clearly, we will also see that accomplice liability is superfluous—that the criminal law does not need a distinct doctrine of complicity.

The four kinds of accomplice who are properly held criminally liable are (a) “truly causal accomplices,” whose acts are indeed causes of the relevant resulting harm; (b) “necessary accomplices,” on whose acts or omissions the resulting harm counterfactually depends; (c) “chance-raising accomplices,” whose acts increase the chance that the harm will ensue but are neither causes of, nor counterfactually necessary for, that harm’s occurrence; and (d) “subjectively culpable accomplices,” who seek to encourage or assist a principal but whose acts actually make no difference at all. But, Moore argues, the grounds for these types of accomplice liability are not peculiar to complicity; they are the four types of desert bases (causation, counterfactual dependence, chance-raising, purely subjective culpability) for criminal liability generally, of “principals” as much as of “accomplices.” Those classed as accomplices are indeed, “in general and on average,” less blameworthy than those classed as principals (for instance, because they generally make a lesser causal contribution to the harm’s occurrence), but, according to Moore, this difference in degree of blame-worthiness is only usual, rather than exceptionless, and is not enough to warrant a categorical distinction between “principals” and “accomplices.”

Moore’s distinctions between the four desert bases depend upon, and help to explicate further, the account of causation that he has been developing over the last decade or so, but I will not be concerned with that account in this brief Response. I will instead, in Part I, ask some questions about the third and fourth desert bases that Moore identifies, before arguing in Part II that there is still some room for a distinctive doctrine of complicity and thus for accomplice liability as a distinctive type of liability. That argument will appeal to the mens rea of accomplice liability rather than to the actus reus (which is the focus of Moore’s argument): my claim is therefore that, even if all that Moore says about the actus reus is right, it does not warrant his conclusion that “aiding another to cause a harm is not a distinct basis for blame and punishment.”