Cicero sets out to define for his son how he should conduct himself when faced with moral decisions. He proposes that the best kinds of decisions are those based on honorableness and utility. Honorable action arises from accordance with the four human virtues (wisdom, justice, greatness of spirit, and moderation). It also concerns the public good, while utility is comprised of things that preserve individual human lives and are thus concerned with the private good.

Obviously, benefits for the public come into conflict with benefits for the private good. In Book III, Cicero tries to reconcile situations in which what is honorable is at odds with what is useful. He argues that other philosophers have wrongly defined anything useful to also be honorable. According to Cicero, something that is useful to one person could also be disgraceful, and, hence, not honorable. Cicero seems to favor honorableness over utility, as actions that are honorable tend to benefit the greatest number of people.

Deciding whether to act in accordance with honorableness or usefulness would have weighed heavy on Cicero's mind at the time of On Duties' writing. If one associates the public good with honorableness and thus service to the Republic, or Senate, it makes sense that Cicero would favor it.