power · Curated Lever · 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.
In 30 seconds
No. Peace can persist when institutions and credible defence make aggression less attractive than restraint or bargaining - even for an actor that prefers conflict.
Read the full explanation ↓The unseen lever
The hidden variable is not goodwill. It is the expected payoff from each available action: attack, wait, negotiate, reassure, or cooperate.
triggerBegin with what an actor expects to gain from aggression. ↓depends onconditionDefensive capability raises the cost of attack only when opponents believe defenders can and will use it. ↓enablesmechanismA credible bargain offers another route to the objective without paying war's expected cost. ↓decreasesconstraintHigher expected costs and a credible alternative make attack less worthwhile, supporting stable peace. ↓decreasesoutcomeBut defensive preparation can also raise threat perception, trigger counter-arming, and weaken trust when intentions are hard to distinguish.
The deeper explanation
The short answer is the start, not the whole story.
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 forces underneath
A bargain is often cheaper than war
War destroys resources and produces uncertain outcomes. In bargaining models, that cost usually leaves room for an agreement both sides would prefer - if they can find it and trust it.
Information is strategic
States may hide capabilities or exaggerate resolve to obtain a better deal. That makes it harder to know which offers are acceptable and which threats are real.
Promises must survive tomorrow
A bargain can fail when one side expects the balance of power to change and cannot trust the future stronger side to keep today's agreement.
Other actors can change the calculation
A credible defensive commitment increases the expected response to aggression. Its effect depends on what allies have promised, whether they can act, and whether an opponent believes they will.
Defence can look like attack
Arming for protection can make an opponent feel threatened. When defensive and offensive preparations are difficult to distinguish, both sides can become less secure even if neither initially wants war.
Incentives
What each actor is trying to do
Potential aggressor
Seek gains through coercion or attack only when expected benefits exceed the combined risk of resistance, third-party intervention, economic cost, and failure.
Potential target
Build enough capability and support to discourage attack without making preparations look like evidence of offensive intent.
Ally or guarantor
Make support believable while retaining control over how it responds and avoiding promises it will not honour.
Institution
Lower uncertainty, create channels for bargaining, define violations, and coordinate responses.
The UN Charter
The Charter supplies a shared legal baseline: members must refrain from the threat or use of force, while Article 51 preserves individual and collective self-defence after an armed attack. The rule changes what can be justified and coordinated; it does not enforce itself.
NATO Article 5
Article 5 treats an attack on one ally as an attack on all, but each ally takes the action it deems necessary. This illustrates the design problem: a commitment must be strong enough to affect an opponent's expectations while remaining politically implementable.
A rapidly shifting balance of power
Imagine State A becoming much stronger next year. A bargain acceptable today may not reassure State B if A cannot credibly promise not to demand more later. The issue is not simply hostility; it is whether today's restraint can bind tomorrow's power.
Who can gain
- States protected by a credible, genuinely defensive arrangement may face a lower risk of coercion.
- All parties can benefit when information and commitments make a cheaper bargain easier to identify and preserve.
Who can bear the cost
- An actor seeking gains through force loses room for a cheap or isolated attack when a collective response is credible.
- Citizens can bear the fiscal, political, and escalation costs of maintaining deterrent capability even when no war occurs.
Second-order effects
- A defensive commitment can reassure the protected state yet alarm outsiders, changing their arming and alliance choices.
- Repeated failure to honour commitments can weaken future deterrence beyond the immediate crisis.
- An overly automatic response can strengthen credibility but reduce political flexibility and increase entrapment risk.
Use the lever elsewhere
The mechanism travels.
Arms-control verification
Verification can reduce uncertainty about capabilities and compliance, making bargains easier to sustain; it cannot remove all strategic incentives to conceal information.
Ceasefire guarantees
Monitoring and third-party guarantees can make renewed attack more observable and costly, but only if enforcement promises are believable.
Cyber conflict
Attribution uncertainty makes it difficult to communicate red lines and predict responses, weakening both bargaining and deterrence.
Common overstatements
More military power always means more peace. No. Capability can deter, but it can also appear offensive and trigger counter-arming. The effect depends on posture, geography, communication, and whether defence can be distinguished from preparation for attack.
A signed alliance automatically makes a threat credible. No. Agreements differ, and empirical results vary by their content and historical setting. Credibility requires expected capability and follow-through, not words alone.
If war is costly, rational actors would never fight. The bargaining puzzle explains why war needs an additional mechanism, not why it is impossible. Private information, incentives to bluff, commitment problems, domestic incentives, and misperception can still break bargaining.
Where the answer stops
The expected-payoff model explains a strategic channel; it does not claim leaders calculate perfectly or that moral beliefs are irrelevant.
The answer synthesizes several schools of international-relations research rather than presenting one theory as complete.
The alliance counterfactual describes directional pressures, not a forecast with a numerical probability.
Peace is not proof that every actor has become peaceful. It may instead show that a system has made restraint, negotiation, or coexistence more attractive than aggression. The harder lesson is that this outcome must be maintained: credibility without reassurance can provoke, reassurance without capability can invite testing, and neither law nor force works independently of institutions and judgment.
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 ↗