Pulse
16 Nov 2026
In 1943, the German theologian Dietrich Bonhoeffer was arrested by the Gestapo for his involvement in the July 20, 1944, plot to assassinate Hitler. He was imprisoned, moved to the Buchenwald concentration camp, and subsequently executed on April 9, 1945, at Flossenbürg concentration camp – just weeks before the war ended.
While Bonhoeffer’s association with the aforementioned plot is widely accepted by mainstream historical scholarship, the precise extent and specifics of his involvement are still being discussed.
This article focuses on the broader question of the moral legitimacy of tyrannicide within the framework of Christian ethics. Are Christians who are specifically commanded not to commit murder (Exodus 20:13) permitted in certain circumstances to assassinate a head of state?
We begin with a definition of tyrannicide.
According to Shannon Brincat, ‘The struggle to craft a working and agreed definition of tyrannicide has resulted in differing emphases on the concept.’ Some writers focus on the nature of the killing of political figures and internationally protected persons, while others are concerned with the political motives underlying the act. Still others focus their attention on the methods used to accomplish the assassination.
For our purposes, we will use the definition offered by the Catholic Encyclopaedia:
Tyrannicide literally is the killing of a tyrant, and usually is taken to mean the killing of a tyrant by a private person for the common good.
It goes on to describe the two classes of tyrants which are helpful for our deliberation.
There are two classes of tyrants whose circumstances are widely apart – tyrants by usurpation and tyrants by oppression. A tyrant by usurpation (tyrannus in titula) is one who unjustly displaced or attempts to displace the legitimate supreme ruler, and he can be considered in the act of usurpation or in subsequent peaceful possession of the supreme power. A tyrant by oppression (tyrannus in regimine) is a supreme ruler who uses his power arbitrarily and oppressively.
With this basic definition in mind, we explore what the Christian tradition has to say about tyrannicide by examining the writings of the great thirteenth-century theologian, Thomas Aquinas. The Angelic Doctor treated this topic in varying degrees of depth in three works: his Commentary on the Sentences of Peter Lombard, the Summa Theologiae, and On Kingship (De Regno).
Space does not allow us to trace Aquinas’ thought in all these works. We will focus on his mature treatments of the subject in the Summa Theologiae and De Regno, which should help us to grasp his position and argument.
SUMMA THEOLOGIAE
Aquinas’ discussion of tyrannicide is found in the section of the Summa Theologiae (Ia, IIae, q.95, art. 4) where he presents his understanding of the different types and divisions of the law. There is natural law and there is civil law, Aquinas teaches, the latter being derived from and grounded in the former.
Reason, Aquinas argues, demands that human laws must always be directed at the common good. All forms of government – Aquinas names monarchy, aristocracy, oligarchy and democracy, following Aristotle – are governed by laws.
All except one: Tyranny. ‘There is also tyrannical government,’ Aquinas writes, ‘which is altogether corrupt, which, therefore, has no corresponding law.’ A tyrannical government is here characterised as lawless insofar as it is governed by the caprice and impulses of the tyrant.
In ST IIa, IIae, q.42, arts. 1 and 2, Aquinas discusses the question of sedition where the topic of tyrants is also briefly addressed. He begins by stating that sedition is a sin which is analogous to war and strife: ‘Sedition is a special sin, having something in common with war and strife, and differing somewhat from them.’
Elaborating on this premise, Aquinas goes on to argue that sedition is a sin because it ‘is contrary to the unity of the multitude, viz. the people of a city or kingdom.’ Additionally, and more pointedly, sedition is a sin because it violates the common good:
Accordingly, the sin of sedition is first and chiefly in its authors, who sin most grievously; and secondly it is in those who are led by them to disturb the common good.
Tyranny, Aquinas asserts, is a form of sedition, perhaps even its most serious and insidious manifestation. He explains: ‘A tyrannical government is not just, because it is directed, not to the common good, but to the private good of the ruler …’ He adds:
… it is the tyrant … that is guilty of sedition, since he encourages discord and sedition among his subjects, that he may lord over them more securely; for this is tyranny, being conducive to the private good of the ruler, and to the injury of the multitude.
Thus, those who oppose such a government are not themselves guilty of sedition – if the opposition is measured and not excessive such that it does not cause more damage than it seeks to mitigate:
Consequently, there is no sedition in disturbing a government of this kind, unless indeed the tyrant’s rule be disturbed so inordinately, that his subjects suffer greater harm from the consequent disturbance than from the tyrant’s government.
Aquinas does not directly address the measures that can legitimately be taken to ‘disturb’ the tyrannical government. Does the great Doctor of the Church endorse tyrannicide?
To answer this question, we must turn to what he has to say about homicide and the role of private individuals and public authority. Summa Theologiae II-II, q. 64, art. 3, makes it quite clear that Aquinas prohibits private individuals from killing evildoers. He reserves this act for public authority that is entrusted with the common good.
Here is his explanation in full:
… it is lawful to kill an evildoer in so far as it is directed to the welfare of the whole community, so that it belongs to him alone who has charge of the community’s welfare. Thus it belongs to a physician to cut off a decayed limb, when he has been entrusted with the care of the health of the whole body. Now the care of the common good is entrusted to persons of rank having public authority: wherefore they alone, and not private individuals, can lawfully put evildoers to death.
The term ‘evildoer’ here is broad enough to include the tyrant.
Thus, private citizens are prohibited from taking the law in their own hands by assassinating a tyrant. However, those in authority can bring the tyrant to trial and lawfully execute him.
DE REGNO
In De Reno (On Kingship), written originally for the King of Cyprus (traditionally identified either as Hugh II or Hugh III), Aquinas revisits the question of the tyrannical government. Delineating the qualities of a good king, Aquinas then argues that a tyrant possesses the exact opposite of those qualities.
Aquinas addresses the question of how to respond to a tyrant in Book 1, Chapter 7, titled ‘How Provision Might Be Made that the King May not Fall into Tyranny.’ He begins by counselling caution in responding to a tyrant, lest the consequences of a premature attempt to overthrow him prove worse than the rule of the tyrant itself.
Indeed, if there be not an excess of tyranny it is more expedient to tolerate the milder tyrant for a while than by acting against the tyrant, to become involved in many perils more grievous than the tyranny itself.
Even when the rule of the tyrant becomes intolerable, it is not permissible for a private individual to assassinate him. ‘If the excess of tyranny is unbearable,’ he writes, ‘some have the opinion that it would be an act of virtue for strong men to slay the tyrant …’ He cites the example of Aioth (Ehud) who slew Eglon, King of Moab (Judges 3:14ff) – an incident cited by some as biblical justification for tyrannicide.
Aquinas insists that such vigilantism is not in conformity with apostolic teaching, citing 1 Peter 2:18-19, which admonishes Christians to be subjected to their masters – even those that are ‘froward’. He points to the example of the early Christians who endured the rule of tyrants:
Wherefore, when many emperors of the Romans tyrannically persecuted the faith of Christ, a great number both of the nobility and the common people were converted to the faith and were praised for patiently bearing death for Christ.
However, this does not mean that there cannot be a just and lawful overthrow and even execution of tyrants. Consistent with his other writings on the subject, Aquinas states in De Regno that ‘it seems that to proceed against the cruelty of tyrants is an action to be undertaken, not through the private presumption of a few, but rather by public authority.’
In De Regno, however, Aquinas also underscores the legitimate role of the ‘multitude’ in deposing a tyrant. What he says here bears reproducing in full:
If to provide itself with a king belongs to the right of a given multitude, it is not unjust that the king be disposed or have his power restricted by the same multitude if, becoming a tyrant, he abuses the royal power. It must not be thought that such a multitude is acting unfaithfully in deposing the tyrant, even though it had previously subjected itself to him in perpetuity, because he himself has deserved that the covenant with his subjects should be kept, since, in ruling the multitude, he did not act faithfully as the office of a king demands.
It would be quite wrong to think that Aquinas is here encouraging violent insurrection in order to depose a tyrannical ruler.
By ‘multitude’ he was not referring to mob politics. Rather, he was referring to that community or corporate body which has exercised its legitimate right and duty to appoint a king through legitimate procedures. That very same body, Aquinas argues, also has the right to depose the king by the same legitimate procedures should he become a tyrant.
CONCLUSION
Based on this reading, it is clear that Aquinas prohibits private acts to depose a tyrant by assassination, insisting that only public authority or the multitude have the right to overthrow him.
How, then, should we evaluate Bonhoeffer’s conspiracy to assassinate Hitler based on Aquinas’ teaching on tyrannicide?
Space does not allow us to answer this question in detail. It may suffice to suggest that a case can be made towards the justification of the intentions of Bonhoeffer and his co-conspirators.
In a situation where all legal and institutional checks have either been eradicated or become complicit – as was the case in Nazi Germany – the ‘appeal to higher authority’ is well-nigh impossible. In fact, it can be said that the conspirators now form that nascent public authority as many in the group were high-ranking military officers, civil servants and intellectuals.
Seen in this way, these conspirators were not ‘private individuals’ but the de facto remnant of a responsible public authority, acting in place of a ruling authority, and using proportionate force for the common good.
Dr Roland Chia is Chew Hock Hin Professor at Trinity Theological College (Singapore).