The Stoics have sometimes been credited with concern for appropriately moral motivation, based on their distinction between those actions they classify as appropriate (kathēkonta) and those they characterize, in addition, as done on the basis of virtue (katorthōmata). This chapter argues that the Kantian and Stoic views closely resemble one another in this respect: just as Kant’s motive of duty requires a singular interest in the rightness of dutiful action, so the Stoics suppose that virtue and actions that originate in virtue are the only objects of fully rational desire. Both theories recognize, as well, that many of our cognitions are not transparent to ourselves, so that we are often unaware of our own motives. This recognition speaks to the depth and complexity of Stoic intellectualist psychology and underlies Kant’s claim that the effort to understand our own moral condition is a “wide” duty of virtue.

This chapter argues against a dominant reading of the Stoics according to which all appropriate actions (kathēkonta), whether drinking when thirsty or standing firm at a critical juncture in battle, count equally as “duties” (officia). All scholars interpret the Stoic Sage’s perfection to imply that absolutely every token action of the Sage counts as a (morally) perfect action (katorthōma), with the result that there is no category of actions constituted by the morally permissible. Appreciating the significance of the misunderstood Stoic category of “intermediate appropriate actions,” however, makes clear that there are actions that follow nature, but that are simply concerned with pursuing “promoted indifferents.” Thus, it is argued that the Stoic position recognizes a class of permissible actions – even for the Sage, whose perfection consists rather in never acting contrary to virtue. The Stoics are thus much closer to Kant and their Socratic heritage than has been previously recognized.

The concept of a ‘formula’ (Formel) plays an important, if complicated, role in Kant’s ethics, especially in the Groundwork. The concept of a formula also plays an important role in Stoic accounts of moral reasoning in the Latin sources, Cicero and Seneca. This chapter explores the place and function of this concept in Stoic ethics and its origins in Roman legal theory and practice. It then raises the question of the relationship between the Kantian and Stoic uses of the concept, asking whether this is a case of direct influence of Stoicism on Kant’s moral philosophy. The chapter comes to no definite conclusion on the question, but aims to provide comparative materials that may help others to address the question.

Cicero’s De Officiis offers the most extensive discussion of the Stoic concept of duty (Greek kathēkon). The chapter addresses the way Cicero introduces into his treatise, with the support of relevant examples, the topic of conflict between different duties and their corresponding actions. The first part of the chapter discusses the influence of the Stoic Panaetius’ treatise ‘On Duty’ on Cicero and Cicero’s divergence from Panaetius in his treatment of conflict of duties. The second part of the chapter analyses how duty applies to different social relationships in De Officiis and how these duties are prioritized, in case of conflict, according to the specific circumstances of action. It is thereby shown that the idea of conflict of duties in Cicero excludes ‘tragic dilemmas’, supporting the Stoic view that there is only one dutiful action to be discharged on every occasion. Finally, the third part of the chapter presents the conflict between the ‘expedient’ and ‘honourable’ courses of action in De Officiis and Cicero’s attempt to present, in line with Stoic views, such a conflict as merely apparent.