Policy Papers

Escaping the Thucydides Trap in political commentary

Neville Morley |

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Executive Summary

  • Thucydides (c.460-404 BCE) wrote an account of the Peloponnesian War between Athens and Sparta (431-404 BCE).
  • He is often seen as the founder of critical historiography, but also as a pioneering political theorist, since he claims his account of the past will be useful in understanding present and future events.
  • Thucydides is currently much in vogue, cited as an authority on global developments such as US-China relations and Brexit, as well as factionalism and populism within democratic politics. However, he did not offer simple principles of political behaviour, based on a timeless and universal human nature, although this is how he is often portrayed today.
  • Rather, he presented a detailed narrative, including reconstructions of speeches and debates, to encourage his readers to reflect on the complex and unpredictable nature of events, the limitations of democratic deliberation, and the power of political rhetoric. It is a high irony that Thucydides himself is now being deployed as a rhetorical device.
  • The more enduring and valid policy lesson to draw from Thucydides is not that human nature is a fixed entity through time, from which secure prognostications can be made, but that democracies are vulnerable to cognitive biases of various kinds, which can be manipulated by adroit rhetoricians.

In recent years, the fifth-century BCE Greek author Thucydides has been perhaps the most widely cited classical authority, appearing in a surprisingly wide range of contexts from discussions of US-China relations to Brexit. Commentators have noted his presence in the Trump White House, cited both by political advisers and military figures, and he has also become more prominent in British political discourse. In many cases, however, he appears simply as an authoritative name attached to a few quotes; the nature of his work, an account of the war between Athens and Sparta known today as the Peloponnesian War (431-404), and the long history of its reception and influence, remains concealed.

Thucydides’ Life and Work

We know relatively little about Thucydides beyond what he says about himself; the two surviving ancient biographies are both much later and of doubtful reliability. He was born around 460 BCE, into an upper-class Athenian family with substantial property – including gold mines – in Thrace. He kept out of politics, but in 424, aged about 36, he was elected as one of the ten Athenian strategoi (generals) and despatched to the northern Aegean, doubtless because of his ties to the region. This was not a success; he failed to arrive in time to save an allied city from falling to the Spartans, and as a result the demos (the citizen body) voted to exile him. He used this opportunity to gather material for a detailed account of the war (which he does not call a ‘history’, a term not yet in common use). He had, he claims, begun writing at its outbreak because he recognised the war’s significance; now he was able to gather testimony from both sides, treating it all critically. Ancient sources and modern historians disagree about when exactly Thucydides died; the work is unfinished, ending in 411, but shows awareness of later events, including the end of the war in 404.

Thucydides was highly regarded as an author in antiquity, but not widely imitated; his style was considered too dense and complicated, and his scrupulous neutrality, not hesitating to criticise his own city, was disparaged. The work was lost to western Europe in the medieval period, but after Byzantine copies were recovered, edited and translated from the fifteenth century onwards, it came to be regarded as a foundation of both critical historiography and political thought. As Thomas Hobbes, who translated it into English, said, Thucydides was “the most politic historiographer that ever writ”.

Reading Thucydides

Thucydides’ work is long and forbidding. A full understanding requires a sense of how he conceives the totality of events and their interconnections, but it is possible to gain insight into key issues – and to make use of the work as a source of ideas and contemporary comparisons – by focusing on a more limited number of passages. Certainly this is how Thucydides has often been read by those who cite him confidently. Studying specific set-piece episodes sheds considerable light on how Thucydides is deployed in contemporary debates. This paper aims to survey the most prominent and important episodes.

Most critical is how Thucydides is read – what kind of author he is assumed to be, and how his text is understood. He is traditionally seen as a historian, and often as the model historian – with his image changing in line with changing views of the historian’s task. He is presented as the master narrator in the eighteenth century, and as the archetypal critical, scientific historian in the nineteenth. Historical readings see Thucydides as focusing on the accurate reconstruction of events as an end in itself, noting how in his introduction he disparages the fact that most people believe any old rubbish about the past and fail to enquire into it critically (1.20-1). In this tradition he is read primarily as a reliable source of information about the past, including exemplary models (the inspiring Athenian leader Pericles) and analogies (the Peloponnesian War as a comparator for the Cold War). This approach tends to downplay the literary elements of Thucydides’ work, as potentially undermining the veracity of his reporting.

However, there is a separate tradition that sees Thucydides as primarily a political theorist, using historical data as the basis for deriving general laws of human behaviour. This reading is based on Thucydides’ claim for the usefulness of his work for someone who wants to understand events that ‘because of the human thing would recur in more or less the same manner in future’ (1.22.4). As with many key lines in Thucydides, there are significant issues of translation – ‘the human thing’, the most literal reading, is often rendered as ‘human nature’, which gives a different impression from ‘ people being the way they are’ – but it is clear that he perceives regularities in human affairs, so that studying the past can illuminate the present and future. Primed by this idea, plenty of readers have identified parallels in his work with their own times. However, there is a further tendency to assume Thucydides is basically a modern political theorist before modernity, even though actual normative political principles are difficult if not impossible to identify in his work. It seems more plausible to assume that his approach is not ‘modern’, but still engaged in the project of thinking about politics (in the broadest sense); his work opens up complexity and ambiguity, rather than seeking to reduce everything to simple or simplistic principles.

The Origins of Wars

Over the last decade, arguably the most prominent evocation of Thucydides – certainly in the American and Chinese media – has been the so-called ‘Thucydides Trap’, a phrase popularised by the Harvard political theorist Graham Allison. This takes Thucydides’ statement about the ‘truest cause’ of the war, that ‘what made war inevitable was the growth of Athenian power and the fear which this caused in Sparta’ (1.23.6), as a general principle that recurs in similar situations. Whenever a ‘rising’ power confronts an ‘established’ power, war is more likely than not. Allison identifies sixteen historical examples, including the Napoleonic, Crimean and World Wars, in which the ‘Trap’ can be identified, but his primary focus is on current relations between the United States and China, offering his work as a warning against complacency. As a result, the Chinese premier and other top officials have regularly engaged with the idea of the Thucydides Trap in order to reject its applicability, while it has become common currency not only in debates about Pacific security issues but in other Asian conflicts such as the relationships between India and China and Pakistan and India.

As an account of Thucydides, rather than simply attaching Thucydides’ name to an already familiar idea from international relations theory, this is problematic. The original Greek is rather more ambiguous and complex. The statement is more literally translated as ‘compelled the Spartans to war’, without the same implication of inevitability. Further, while Thucydides offers this as his own judgement about the ‘truest but least discussed’ cause of the war, he follows it with a detailed account of how war actually broke out, through a sequence of events and decisions, by individuals and states all pursuing their own interests. In other words, far from offering a single universal principle to explain events, Thucydides offers a complex study of the interplay of individual and state decisions, the characters of different peoples, short-term events and underlying structures, and chance.

Thucydides describes debates, at Athens and Sparta, in the run-up to the war, in which claims are made about state motivation; for example, the Athenian description of the acquisition of their empire: ‘fear was the strongest motive, followed later by honour and then by self-interest as well’ (1.75.3). The idea that all states are driven by some combination of these three motives has become established as a basic tenet of ‘Realism’ in International Relations theory. Certainly Thucydides’ characters claim these are universal motives, but it is not obvious that we should take this at face value, since the speakers are seeking to persuade others of their case. In addition the subsequent narrative shows that all three motives, fear, honour and self-interest, can be understood in very different ways and heavily influenced by emotions, rather than being the clear bases for rational calculation that Realism supposedly promotes (and ascribes to Thucydides).

Democracy Celebrates Itself: the Funeral Oration

The source of many of the most familiar quotations from Thucydides – ‘the many not the few’; ‘our constitution is called a democracy’; ‘the whole earth is the tomb of famous men’; ‘happiness depends on freedom and freedom on courage’; ‘freedom is the sure possession of those alone who have the courage to defend it’ – is the so-called Funeral Oration, delivered by the Athenian politician Pericles at the end of the first year of the war (2.35-46). Pericles’ praise of Athens and its society has been adopted by modern liberal democracies as a statement of their own values (including the ill-fated draft constitution of the European Union of 2003), while his call for citizens to fight to defend it has been deployed to justify conscription in the First World War, used widely on war memorials (especially in ANZAC contexts, but also on the Bomber Command memorial in Green Park) and cited by veterans’ organisations to emphasise their contribution.

It seems unlikely that the speech recorded in Thucydides is a perfect transcript of what Pericles actually said. He admitted that it was difficult for him, as for other witnesses, to recall precise details of speeches, and so he set down what it was most appropriate for speakers to have said in the circumstances, while sticking as closely as possible to what was actually said (1.22.1). The exact meaning of this gnomic phrase has troubled generations of historians, to whom it looks alarmingly like non-historical invention. It is generally assumed that Thucydides used speeches for several purposes at once: characterising the speakers’ views (including ones they might not have expressed openly in reality), presenting their character, and summing up a situation and the options available to those making a decision.

In the case of the Funeral Oration, we are offered an image of Athens as an open, liberal democracy, and of Pericles as its embodiment. Many readers think Thucydides was an admirer of Pericles (as ‘the first man’ who was able to control the irrational demos without them realising), or indeed that the whole point of his history was to justify Pericles’ policy, and see this speech as a simple heroization. A more critical reading emphasises how far Pericles’ account of Athens is rather odd – in his call for citizens to become ‘lovers of the city’, in his dismissal of wives and families – and even coercive, a subtle indictment of his imperious style and imperial plans that had led Athens into an avoidable war.

Plague and Civil War

Pericles, having persuaded the Athenians to reject the Spartan ultimatum and therefore precipitated war, pursued a strategy of exhaustion; rather than confronting the invading Spartan forces, the Athenians withdrew within their walls and relied on their fleet for supplies and to strike at the enemy elsewhere. This was deeply unpopular with citizens who saw their fields being ravaged. Whether the plan would have succeeded eventually is one of the key counterfactuals of Thucydides’ account, since the concentration of people in the city led to a devastating outbreak of plague (the precise nature of which is fiercely disputed) and to the death of Pericles. His successors adopted more aggressive strategies, since (Thucydides claims) they lacked his authority and so pandered to the whims of the people.

Thucydides’ depiction of the plague (2.47-54), and the way the Athenians responded to it by abandoning social norms and behavioural restraints, is a powerful piece of social analysis. It is echoed in his description of the ‘stasis’ (civil breakdown or internal conflict) in the city-state of Corcyra (3.70-83), in which the political community collapsed into democratic and oligarchic factions, each seeking outside help to defeat the other. In both cases, we are given a sense of the fragility of society, its vulnerability to external events (plague, war). The Corcyrean stasis shows the process of escalating polarisation, in which factional loyalty trumps communal and even family ties, and the collapse of common norms and values, so that ‘moderation’ comes to be seen as cowardice and pre-emptive violence against the enemy is simply common sense. It is suggested that the passage influenced Hobbes’ depiction of the ‘war of all against all’ in the state of nature; it has certainly seemed to some recent commentators to offer a prescient image of contemporary political infighting, polarisation and culture war.

The Mytilenean Debate and Democratic Deliberation

The Athenian ‘empire’ had originated as a defensive alliance against the Persians, known today as the Delian League. Originally, all members contributed ships and men, with Athens having greater influence as the largest power. Over time, however, Athens increasingly used the League’s ships as its own navy, a process that was accelerated by having other members contribute money to support Athenian ships rather than sending their own forces – which also, Thucydides notes (1.99) reduced their ability to rebel, as they had outsourced most of their military capacity. The outbreak of war appeared to some of these ‘allies’ as an opportunity to escape Athenian tyranny, and in 428 BCE the city of Mytilene, the largest city-state on Lesbos, revolted. Athenian forces blockaded the city, and a fleet sent by Sparta to support the Mytileneans arrived too late.

The focus of Thucydides’ account of this episode (3.36-49) is the debate in the Athenian assembly about the treatment of the defeated Mytileneans. This was the day after the demos had voted to massacre the entire male population and sell the women and children into slavery. Thucydides presents two speeches, one by Cleon, the populist politician (or ‘demagogue’) who became prominent in Athenian politics after the death of Pericles, and one by the otherwise unknown Diodotus. The former argues for consistency in decision-making, disparaging the rhetoric of those who seek to be cleverer than the ordinary citizens, and for the need to deter other potential rebels; the latter argues that milder punishment will be more effective, as otherwise rebels will always fight to the death rather than surrendering. It is notable that neither speaker offers any arguments grounded in ethics, only pragmatism. The assembly narrowly voted to rescind the previous day’s order, and despatched a ship to Mytilene with its new decision; this arrived just in time to prevent the massacre.

In recent years, the Mytilenean Debate has been cited in the context of Brexit, as the key example of a democracy changing its mind without the legitimacy of this change of heart being called into question. Thucydides appears to be more interested in what the episode reveals about Athenian thinking at this stage in the war – the willingness to take ruthless action in defence of its empire, the exclusion of ethical considerations from decision-making – and about the workings of Athenian democracy. Both Cleon and Diodotus comment on the susceptibility of the citizens to emotional reactions and rhetorical manipulation – as a means of presenting themselves as honest and trustworthy – with the latter suggesting that it is necessary for well-meaning politicians to lie to the people for their own good. As readers, we can identify the ways in which they seek to manipulate their audience with loaded words and arguments, and are encouraged to reflect on how far this account of democracy is true; we are put in the position of hearing the persuasive words of clever speakers and having to work out how to resist them.

The Melian Dialogue and the Pathologies of Power

By 416, Athens and Sparta had fought themselves to a standstill, and signed a peace treaty. Neither side saw this as anything more than a temporary cessation in hostilities, and Athens in particular took the opportunity to extend its power elsewhere. It despatched a force to the neutral island of Melos and demanded its unconditional surrender. Thucydides (5.84-116) presents a dialogue between the Athenian commanders and the Melian leaders, in which the latter desperately tried to persuade the former to relent. Eventually the Melians decided that they preferred doomed resistance to the loss of their independence; the siege lasted about six months, and ended with the predicted slaughter of the male citizens and the enslavement of the women and children.

Even more than the other speeches in his account, it is hard to see the Melian Dialogue as anything other than Thucydides’ own invention; he was not present and there were few if any surviving witnesses to interrogate later, and it too much resembles the script of a tragic play. The question is what function it serves in his narrative, besides its intrinsic drama. Certainly it offers an example of Athens’ entirely instrumentalist attitude at this stage in the war, their refusal even to consider arguments about ethics, norms or historical obligations, and their blithe dismissal of the suggestion that their ruthlessness might have adverse consequences. You’ll set an example for others that will be turned against you, say the Melians, and no neutral state will ever trust you. That’s fine, the Athenians respond; if we let you live, it looks like weakness, and we’re mainly concerned with deterring our subjects from rebellion. The gods are not going to save you – why imagine that they’re on your side rather than ours? The Spartans won’t come to rescue you, either. Your obsession with honour rather than safety is going to lead you into disaster; you must be the only people who imagine that what might happen in future is more certain than what is. happening to you now if you don’t surrender.

For modern scholars who see Thucydides as a political theorist, the Melian Dialogue is the key source text for the reconstruction of his ideas. It is conventionally understood as the founding statement of ‘Realism’: the world is anarchic (i.e. there are no over-arching international institutions or norms to regulate inter-state behaviour), and so the only rational approach is to proceed on the basis of calculations of power and advantage. ‘Stand up to your equals, defer to your superiors, and be moderate towards your inferiors,’ as the Athenians say at the end. And more famously, early in the exchange, ‘questions of justice apply only between equals; otherwise the powerful exact what they can and the weak endure what they have to’ (often quoted as ‘the strong do what they can and the weak suffer what they must’). These ideas, interpreted as normative political principles, have inspired a whole tradition of thought in International Relations, as well as being deployed to characterise situations of power imbalance, such as the negotiations between Greece, the EU and the IMF (Yanis Varoufakis, formerly Greek Finance Minister, called his book on the crisis And the Weak Suffer What They Must?) – or the negotiations between the United Kingdom and the EU.

But it is important to stress that these are words that Thucydides puts into the mouths of his characters, not his own explicit theory of inter-state politics; it is an enormous interpretative leap to assume that he agreed with them or saw them as true statements about the world, especially given that this was the attitude that subsequently led Athens into disaster. That isn’t to say that he agreed with the Melians instead; they appear to be equally delusional and irrational in their decision-making. Rather, we can see this as a powerful depiction of the ways that both the powerful and the weak think and speak, the equally problematic ways in which they view the world, and the dynamics of the relationship between them. Like the agon (contest scene) in the Greek tragedies that it somewhat resembles, the Melian Dialogue is intended to make visible the competing perspectives and assumptions of its protagonists; it does offer understanding of events that are likely to recur in future, as Thucydides had promised, but in the form of questions and contestable ideas, not universal laws of history or politics.

The Sicilian Debate and the Limits of Human Judgement

For many readers of Thucydides, the culmination of the narrative is the Sicilian Expedition of 415-13, in which the Athenians – powered by the unchallengeable arrogance depicted in the Melian Dialogue – launched an ambitious expedition against the city of Syracuse, that failed miserably and brought about their defeat. Thucydides’ account in fact continues for another book (albeit an unpolished and rather disjointed one), and the war continued for nearly ten more years before Athens finally surrendered, but there is a powerful sense that this was the turning point, after which Athens had lost any hope of defeating Sparta but could only lose, sooner or later. The depiction of the disastrous expedition (6.63-7.87), and especially the final battle and the ignominious retreat, is a powerful piece of historiography, but the more obviously ‘useful’ element of this section is Thucydides’ account of the debate in the Athenian assembly over the launching of the expedition (6.9-24), setting the cautious and conservative Nicias against the flamboyant, ambitious young Alcibiades.

There are echoes of the Mytilenean Debate in this depiction of democratic discourse and the power of rhetoric, but here the stakes are higher: the underlying question is why the Athenians came to make such a terrible decision. Thucydides emphasises their ignorance of the country they were about to invade and their confident over-estimation of their own strengths, suggesting his belief that the plan was doomed. We are offered the opportunity to consider why Nicias’ arguments proved insufficiently persuasive to the Athenians, and how Alcibiades’ speech pushed the right buttons. In modern terms, we could understand this as a study of different cognitive biases: among others, confirmation bias (all information is filtered through the Athenians’ belief in their own power and invincibility), groupthink and the bandwagon effect (‘in the face of this extreme passion on the part of the majority, anyone who felt otherwise was afraid of seeming disloyal if he voted against and therefore held his peace’: 6.24.4), and the Dunning-Kruger effect visible both in Alcibiades’ boundless confidence in his own talents and the Athenians’ arrogance. Again, the power of Thucydides’ account – while also a source of frustration for those readers who want clearer statements of his views – is the way that we experience this debate as spectators, being worked upon by the rhetoric of the speakers just as the original audience was, rather than cool evaluation and analysis of it.

The Sicilian Debate and the subsequent expedition are less widely cited in wider debates than other passages. The episode was evoked in the run-up to the invasion of Iraq; the historian Donald Kagan (associated with the neoconservatives, both directly and through his sons) had argued that the Sicilian Expedition could have succeeded with better planning and more luck, a claim that was interpreted as a means of dispelling concerns about the wisdom of the Iraq enterprise, while opponents of the war argued that it showed the inevitability of its failure. More recently, commentators on the Brexit project have claimed to identify parallels, especially in confident claims about the inevitability of success and attacks on naysayers as unpatriotic. If so, there must be concern about Thucydides’ sardonic comment on the reaction in Athens when news of the disaster arrived: ‘When they had taken it in, they turned their anger on the orators who had joined in promoting the expedition – as if they had not voted for it themselves…’ (8.1.2).


Thucydides’ modern reputation is as a hard-headed realist – if not a Realist, then at least someone who sees the world as it really is rather than through a filter of optimism or idealism – and as someone who truly understands events; “exiled Thucydides knew”, as W.H. Auden remarked on the rise of Hitler and the outbreak of the Second World War. This rests both on the assumption that human affairs – at least in the spheres of politics and war – are sufficiently regular that the past can illuminate the present, and on the power of Thucydides’ text to persuade readers to see such parallels. He does not, however, offer laws or principles to be applied, but dramatic scenes to be meditated upon – and a caution against any temptation to believe that we can fully grasp a situation or predict its outcome.

Further Reading

Thucydides’ work is available in many different modern translations and editions. The Oxford World Classics edition translated by Martin Hammond (2009) and the Cambridge Texts in the History of Political Thought edition translated by Jeremy Mynott (2013) have both been praised for their clarity and accuracy. The widely-used Landmark Thucydides edited by Robert B. Strassler (revised edition, 2008) has excellent maps and other supporting material, but is based on the rather unreliable 19th-century translation by Richard Crawley. The quotes from Thucydides in this paper are based on Mynott, using the standard format of book and chapter numbers. For Realism see works below by Crane and Gustafson.

G. Allison, Destined for War: can America and China escape Thucydides’s Trap? (Harvard University Press, 2017)

W.R. Connor, Thucydides (Princeton University Press, 1987)

G. Crane, Thucydides and the Ancient Simplicity: the Limits of Political Realism (University of California Press, 1998)

E. Greenwood, Thucydides and the Shaping of History (Bloomsbury Academic, 2006)

L.S. Gustafson, ed., Thucydides’ Theory of International Relations: a Lasting Possession (Louisiana State University Press, 2000)

G. Hawthorn, Thucydides on Politics: Back to the Present (Cambridge University Press, 2014)

D. Kagan, Thucydides: the Reinvention of History (Viking, 2009)

C. Lee & N. Morley, ed., A Handbook to the Reception of Thucydides (Wiley-Blackwell, 2015)

Web links

M. Crowley, ‘Why the White House is reading Greek history’, politico.com, 21 Jun 2017: https://www.politico.com/magazine/story/2017/06/21/why-the-white-house-is-reading-greek-history-215287

C. Higgins, 'The time a second referendum saved thousands of lives', Prospect Magzine, 18 Oct 2018 https://www.prospectmagazine.co.uk/magazine/the-time-a-second-referendum-saved-thousands-of-lives

C. Oliver, ‘Britain needs a last-minute Greek lesson’, politico.eu, 23 Feb 2019: https://www.politico.eu/article/britain-brexit-greece-needs-a-last-minute-greek-lesson/

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