Duty is often contrasted with affection, as one can act out of duty without feeling affection for the person whose well-being is the object of that duty. But is it possible to act out of duty (or, out of justice), without benevolence? It seems that this is possible as well--a "motivating" or general virtue, whether it be general justice or charity or benevolence, is not necessary for someone to act justly out of the virtue of justice.

Is it necessarily Kantian to speak of duty? No. But it seems undeniable that a Thomistic understanding of duty (and its relation to virtue) is different from the account of duty given by Kant.