There ought to be a limit to the way we think of free will's influence on responsibility in the first place. It's rarely the case, if ever, that a person's actions aren’t already predetermined by a complex of prior judgments, personal outlook and knowledge, and circumstance. When someone does something wrong, we may be tempted to think of ourselves as magnanimous for blaming the culprit for only her actions, but with truly transgressive acts we’re apt to blame not the person’s will, but her attitude. Is it wrong to hold someone to account for their attitude?
When we think of free will generally, it’s not the case of coercion we should be considering but the case of freedom. If, when coercion is absent, and one has an opportunity to reflect on personal attitudes towards others but doesn't, do we blame her for that restraint in character improvement? It makes little sense to do so until that untreated attitude gives way to some heinous act, but after the fact we ought to engage in some correction of her attitude if we truly believe her actions were wrong. This being the case, what form should that correction take?
A “Just Deserts” theory would have it that her failure to correct herself is what makes her deserving of penalty, but one would think that this view must presuppose a real, and more tangible notion of free will than most compatibilists may be willing to stomach. However, it doesn’t seem outside the bounds of justice to point out to our culprit that her actions were seen as wrong, and thus why the attitudes that led her to act so are, by extension, also wrongly held. Let’s call this “instructional” punishment. Correction through education, rather than rehabilitation.
This doesn’t ask us to buy into an ontology of free will; we only need to draw a line at its existential limit and treat people as-if they are freely willing agents to continue serving justice. Once we assume real desert must be addressed by anything greater than this wholly normative concept of “deserving”, then we’ve either seriously bought into free-will libertarianism already, or have some other idea of “deserving” for which freely willed action plays no role.
Can such deserts - which are detached from the normal mode of forming intentions and carrying them out - really exist?