War

War has been the constant background condition of the political order the conservative tradition seeks to preserve. The Roman, medieval, and early-modern statecraft from which the tradition draws was practical statecraft addressing the perennial question of how a community defends itself from external threat while remaining a community worth defending. The tradition’s contribution has been to insist that the second concern constrains the first: a war fought without moral limits damages the polity that fights it as surely as a war refused damages the polity that should have fought.

What the conservative defends, in this domain, is the just-war framework — the conditions under which a state may resort to force and the limits on how it may use force once resort is justified — as the accumulated wisdom of Christian and classical reflection on the practical reality of political violence.

Key takeaways

• War, in the conservative tradition, is an enduring feature of political life under a fallen human nature — not a problem to be solved by institutional design but a condition to be limited by prudence, moral law, and the just-war framework the Western tradition has developed across two millennia.
• The conservative reading treats peace as a contingent achievement of statecraft and military readiness rather than as the natural state of mankind, and is wary of both the pacifist position that condemns all use of force and the crusading position that authorises it without restraint.
• The dispute between conservatives and their critics is less about whether war is terrible — the tradition is unsparing on this — than about whether its prevention is best secured by international institutions, by hegemonic balance, or by the older combination of national strength, allied commitments, and explicit moral limits on the conduct of war itself.

History and context

The classical inheritance contributed two foundational sources. Thucydides’ History of the Peloponnesian War (c. 400 BC) supplied the realist analysis of war’s causes — fear, honour, interest — that the Western tradition has never been able to forget, even when it has wished to. Cicero’s De Officiis (44 BC) supplied the earliest systematic articulation of conditions on the just resort to war: legitimate authority, just cause, and proper conduct in the prosecution of the cause.¹

The Christian elaboration came in two stages. Augustine, writing in the City of God (413–426) and in scattered letters, accepted the classical conditions and added the moral framework: war is a remedy for grave injustice in a fallen world, undertaken with the love of peace as its ultimate end, and never as the expression of vengeance, cruelty, or lust for domination. Thomas Aquinas systematised this framework in the Summa Theologiae (II-II, q. 40), setting out the three conditions — legitimate authority, just cause, right intention — that constitute the jus ad bellum and indicating the further conditions of proportionality and distinction that constitute the jus in bello.²

The early-modern jurists adapted the framework to the emerging state system. Francisco de Vitoria’s lectures De Indis (1539) extended the just-war analysis to the Spanish encounter with the New World, holding that conquest could not be justified by mere religious difference and that the indigenous peoples possessed political authority that the conqueror was bound to respect. Hugo Grotius’s De Jure Belli ac Pacis (1625) supplied the synthesis that founded the modern law of war: that the conduct of states toward one another, even outside the framework of a shared sovereign, was bound by natural law and by the customs of nations.³

The twentieth century produced both the most destructive wars in human history and the most ambitious efforts to abolish war as an instrument of policy. The League of Nations (1920), the Kellogg-Briand Pact (1928), and the United Nations Charter (1945) each represented an attempt to subordinate the resort to war to a legal regime. The conservative assessment of these institutions has been mixed: respectful of their aims, sceptical of their capacity, and attentive to the way that the legal-internationalist framework has tended to coexist with rather than displace the older logic of national interest and strategic balance. Reinhold Niebuhr’s Moral Man and Immoral Society (1932) and The Children of Light and the Children of Darkness (1944) supplied the realist theological framework that shaped the broader American conservative reading of the postwar order: a position of “Christian realism” that supported the United Nations without expecting it to abolish the conditions that made war recurrent.⁴

The post-1945 nuclear age produced new questions and a partial re-elaboration of the just-war tradition. The bishops of the Roman Catholic Church, in The Challenge of Peace (1983), engaged the morality of nuclear deterrence with seriousness; James Turner Johnson, Paul Ramsey, and Michael Walzer developed the academic just-war revival of the 1970s and 1980s, with Walzer’s Just and Unjust Wars (1977) becoming the standard text.⁵ Conservative thinkers including George Weigel and Joseph Bottum elaborated the just-war framework in light of the wars that followed September 11, 2001, with sustained disagreement about whether the post-2003 Iraq War met the conditions of just cause and reasonable hope of success.

The conservative position

Three claims structure the tradition.

First, war is a perennial fact, not a soluble problem. The conservative reads the historical record — the unbroken sequence of wars across the recorded history of every continent — as evidence that the appetites and interests that produce war are constitutive of political life rather than incidental to a particular stage of it. This does not entail fatalism: particular wars can be prevented by particular acts of statecraft. But it does entail prudence about programmes whose announced goal is the abolition of war as such, since such programmes have a tendency to leave their subscribers unprepared for the wars that the programmes have not in fact abolished.

Second, the just-war framework remains the moral language of legitimate force. The conservative tradition treats the jus ad bellum and the jus in bello not as residual scholastic categories but as the working vocabulary in which the moral questions about force can be addressed. The framework supplies a discipline that the alternative vocabularies — humanitarian intervention, the responsibility to protect, geopolitical realism — supply only intermittently. The tradition’s contribution to twenty-first-century debate is to insist that these alternatives, where they are sound, are sound because they recover elements of the older framework, and where they are unsound, are unsound because they have departed from it.

Third, military strength is a condition of peace, not a threat to it. The peace the conservative seeks is the peace of a polity capable of defending itself: a polity that, by being capable of defence, deters the attacks that would otherwise produce wars. The Roman maxim si vis pacem, para bellum expressed an older form of the conviction. The post-1945 American Cold War strategy of containment, as articulated by George Kennan and refined by figures including Paul Nitze and James Schlesinger, applied the conviction to the Soviet threat with sufficient success that the long contest ended without general war.⁶

Differing positions

The pacifist position, in its strongest religious form, holds that the Christian commitment to non-violence makes participation in war morally impermissible for the believer. Stanley Hauerwas has developed the most sustained twentieth-century defence of this position within Protestant ethics. The conservative reply, working from the Augustinian and Thomistic inheritance, accepts the witness of the pacifist tradition as a particular calling — for monks, for certain religious communities — without conceding that it constitutes the binding doctrine of the universal Church or the principled rule of the political community. The state, on the conservative reading, bears a duty of protection that the Christian pacifist does not bear in his own person.

The realist position, in the academic tradition descending from Hans Morgenthau and the Cold War strategists, treats moral categories as supplements to or constraints on a fundamentally interest-based analysis of war. The conservative engagement with realism is sympathetic but unwilling to accept the full reduction. The tradition holds that interests themselves are partly constituted by moral commitments — that what a state takes to be in its interest depends on what kind of state it is — and that the realist’s exclusion of the moral dimension is incomplete as analysis even when it is shrewd as advice.

The cosmopolitan-liberal position, articulated most influentially by Michael Walzer in Just and Unjust Wars and by the “responsibility to protect” doctrine that gained currency after 2001, presses for an expanded right of humanitarian intervention against states that grossly mistreat their own populations. The conservative response is divided. The Catholic just-war revival has been broadly sympathetic; the realist and paleoconservative strands have been sceptical, pressing on the practical record of post-1990 interventions and on the institutional erosion that follows from the routine resort to force in the name of humanitarian principle.

References

1. Cicero, De Officiis, trans. Walter Miller (Cambridge, MA: Loeb Classical Library, 1913), I.34–40.
2. Augustine, Letters 138 and 189, in Political Writings, ed. E. M. Atkins and R. J. Dodaro (Cambridge: Cambridge University Press, 2001); Thomas Aquinas, Summa Theologiae, II-II, q. 40.
3. Francisco de Vitoria, Political Writings, ed. Anthony Pagden and Jeremy Lawrance (Cambridge: Cambridge University Press, 1991); Hugo Grotius, De Jure Belli ac Pacis, trans. Francis W. Kelsey (Oxford: Clarendon Press, 1925).
4. Reinhold Niebuhr, The Children of Light and the Children of Darkness (New York: Charles Scribner’s Sons, 1944).
5. Michael Walzer, Just and Unjust Wars: A Moral Argument with Historical Illustrations, 4th ed. (New York: Basic Books, 2006); James Turner Johnson, Morality and Contemporary Warfare (New Haven: Yale University Press, 1999).
6. George F. Kennan, American Diplomacy, expanded ed. (Chicago: University of Chicago Press, 1984).