Scholarship on De Officiis tends to place the emphasis on those aspects of the treatise that outline the building blocks of a functioning commonwealth. What tends to receive rather less attention is Cicero’s theorizing of what to do in situations of communal breakdown. But in De Officiis he is as interested in injustice as he is in justice, in the ability of humans to inflict massive damage on each other, in the insufficiency of legislation to ensure harmonious co-existence, in fraud and abuse of power. To address the problem of harm and injustice Cicero calls for vigilance and intervention on the part of all members of the community and endorses ‘protective violence’ up to and including the license, indeed the duty, to kill tyrannical figures that threaten the fabric of communal life. This chapter argues that Cicero’s ethical extremism animates the entire treatise. To render this claim plausible it explores the historical circumstances that gave rise to it and traces its ubiquitous presence within De Officiis, with a particular focus on the conceptual strategies used to justify murder.

On the Ides of March 44 BC, a momentous occasion took place in the history of Rome: Julius Caesar was assassinated in a crowded meeting of the senate.1 Almost immediately the scramble to define, legitimize, and record the act was set in motion. Marcus Junius Brutus, we are told, raised his dagger in the air and called on Cicero, presumably hoping he would be the ideal advocate for their deed; after all, Cicero had spoken out vigorously against tyranny in his published works, and this is the line they wanted to take now: that Caesar was a tyrant justly slain. For the same reason, the assassins took control over their image by rebranding themselves as ‘Liberators’ – that is, as the men who had freed Rome from Caesar’s rule. On the afternoon of the Ides, Brutus and Cassius attempted to address the people of Rome in a contio – a public meeting hastily convened in the forum. But there was little public support either then or in the meetings that followed.

The most obvious use of philosophy within Cicero’s speeches is as a source of invective: Stoicism against Cato in the Pro Murena, Epicureanism in In Pisonem. However, even here Cicero is careful to show that philosophical adherence itself is not a fault; but only faulty adherence. Elsewhere in the speeches, Cicero draws on Stoic theories of society in constructing his views of the relationship between the res publica, crisis, and tyranny and in articulating the justification for tyrant killing: this line of argument can be traced from the Catilinarians through Pro Milone down to the Philippics.

Tyrannicide is a political act, which Ford describes as ‘a circle within a circle within a circle’ limited to striking down illegitimate, capricious or impious rulers and constitutes the ‘only respectable link between ethics and political violence’.1 It is parasitic in nature, being reliant on extant illegitimacy for its legitimacy. Its history is also subject to the history of tyranny and is nearly as old; as soon as archaic Greece came to regard tyranny as negative, tyrannicide became legitimate. This chapter also considers two other concepts: tyrannophobia and tyrannophilia. Tyrannophobia, as defined by Hobbes, is an under-identified but simmering presence in tyrannical discourse which impacts on the ability to diagnose tyranny’s presence. Tyrannophilia, as defined by Mark Lilla, describes the interrelationships between theoretical discourse and political support of tyranny. Much of this book focuses on those discussing tyranny, rather than tyrants and tyrannophilia, but this chapter locates the connections between them.

Chapter Six analyses the De Justa Reipublicae Christianae Authoritate (1590) of the pseudonymous ‘Guiliemus Rossaeus’ to demonstrate how a deep analysis of the relationship between natural and divine law, in scholastic terms, was used to justify the deposition and assassination of Henri III. Rossaeus' rich engagement with Jesuit and Dominican casuistry, and the Thomist commentary tradition, made his rejection of heretic tyranny a question of individual conscience as well as of French heresy laws. This demonstrates that Leaguer analyses of papal power at this academic level were not simply a recapitulation of medieval ecclesiological debates but offered a fresh synthesis of the Thomist sources. Such theories were as much a contribution to European Catholic political-theological debate as they were an immediate polemical response to Henri III’s perceived tyranny.