power · Curated Lever · 4-7 min
Does peace require everyone to want peace?
Peace can survive hostile intentions when the system changes what aggression is expected to cost - and when restraint remains credible too.
The intuitive answer
The intuitive story says peace exists because all sides agree that war is wrong. Shared norms can matter, but this explanation is fragile: one actor with different preferences would be enough to break the system.
The short answer
No. Wanting war and choosing war are different things. Rules, defensive capability, information, and credible collective commitments can make aggression costlier and less likely to succeed, so even a hostile actor may prefer restraint or bargaining. But deterrence is conditional: threats that lack credibility may fail, while threatening preparations can make opponents feel less safe and produce escalation instead.
The unseen lever
The hidden variable is not goodwill. It is the expected payoff from each available action: attack, wait, negotiate, reassure, or cooperate.
- 01Begin with what an actor expects to gain from aggression.
- 02Defensive capability raises the cost of attack only when opponents believe defenders can and will use it.
- 03A credible bargain offers another route to the objective without paying war's expected cost.
- 04Higher expected costs and a credible alternative make attack less worthwhile, supporting stable peace.
- 05But defensive preparation can also raise threat perception, trigger counter-arming, and weaken trust when intentions are hard to distinguish.
Concepts that unlock it
Bargaining range
The set of deals both sides prefer to the expected cost and risk of fighting.
Deterrence
Changing another actor's choice by making aggression look too costly or unlikely to succeed.
Credible commitment
A promise or threat others have good reason to expect will be carried out.
Security dilemma
A situation where one actor's attempt to become safer makes another feel less safe.
Collective defence
An arrangement in which participants promise assistance when one of them is attacked.
What if?
What if members of a defensive alliance kept the same military capability but repeatedly failed to support one another?
Check your understanding
Can you move the mechanism?
Question 1 of 2
Why can peace persist even when one state would prefer to gain something by force?
Choose the best explanation.
Question 2 of 2
An alliance keeps the same weapons and forces, but repeatedly fails to support members it promised to defend. What changes first?
Choose the best explanation.
Evidence and limits
What supports this answer?
Because war is costly and risky, bargaining models usually imply a range of settlements that both sides would prefer to fighting, provided they can identify and enforce such a settlement.
Limit: Leaders may value outcomes differently from citizens who bear war's costs.Limit: Misperception, emotion, domestic politics, indivisible claims, and implementation constraints can narrow or obscure the bargaining range.James D. Fearon; International Organization - Rationalist Explanations for War ↗Private information about capability or resolve, combined with incentives to exaggerate, can prevent opponents from locating a mutually preferable bargain.
Limit: Signals may reveal information, but costly signals can also escalate a crisis.James D. Fearon; International Organization - Rationalist Explanations for War ↗A peaceful bargain can fail when one side cannot credibly promise not to exploit a future shift in bargaining power.
Limit: Not every power transition creates a commitment problem or war.Robert Powell; International Organization - War as a Commitment Problem ↗Even status-quo states can become less secure when measures taken for defence appear threatening and trigger countermeasures.
Limit: The dilemma is weaker when defensive postures are distinguishable from offensive ones.Limit: Some actors are expansionist; the security dilemma does not assume all conflict is accidental.Robert Jervis; World Politics - Cooperation Under the Security Dilemma ↗International institutions can change the choice environment by prohibiting force, authorizing collective self-defence, and specifying procedures for cooperation, even though rules do not enforce themselves.
Limit: A legal rule is evidence of institutional design, not proof that violations will always be prevented or punished.United Nations - Charter of the United Nations ↗A collective-defence commitment can deter by changing an aggressor's expectation of third-party intervention, but credibility depends on the agreement's content and expected implementation.
Limit: Capability without believed willingness may not deter.Limit: Ambiguity can sometimes reduce entrapment but can also weaken deterrence.North Atlantic Treaty Organization - The North Atlantic Treaty ↗Brett Ashley Leeds; American Journal of Political Science - Do Alliances Deter Aggression? The Influence of Military Alliances on the Initiation of Militarized Interstate Disputes ↗The empirical literature does not support the blanket claim that every defensive alliance always prevents war.
Limit: Alliance formation is endogenous: states form alliances partly because they already face danger, complicating causal inference.Michael R. Kenwick, John A. Vasquez, and Matthew A. Powers; The Journal of Politics - Do Alliances Really Deter? ↗Brett Ashley Leeds; American Journal of Political Science - Do Alliances Deter Aggression? The Influence of Military Alliances on the Initiation of Militarized Interstate Disputes ↗Peace does not logically require every actor to value peace for its own sake; it can persist when rules, capabilities, information, and credible commitments make aggression less attractive than restraint or bargaining.
Limit: The claim is about possibility and mechanism, not a guarantee or moral endorsement of deterrence.Limit: Peace can also be supported by legitimacy, norms, interdependence, domestic institutions, reconciliation, and accurate information.James D. Fearon; International Organization - Rationalist Explanations for War ↗Robert Jervis; World Politics - Cooperation Under the Security Dilemma ↗