Thomas Jefferson once compressed one of the great lessons of political history into a single sentence: "War is an instrument entirely inefficient toward redressing wrong; and multiplies, instead of indemnifying losses."
It is tempting to dismiss such words as pacifist idealism. Nations sometimes must fight. An invasion cannot necessarily be stopped by diplomacy, and a population facing extermination can hardly be told that violence is philosophically undesirable. Jefferson himself belonged to a revolutionary generation that had taken up arms against Britain. His point was therefore more sophisticated than the proposition that force is never justified. The crucial word is redressing.
War is remarkably good at destroying things. It can destroy armies, governments, cities, infrastructure and sometimes entire political systems. What it is much less capable of doing is restoring the world that existed before the original wrong occurred. The dead do not return when the enemy is defeated. Destroyed families are not reconstructed by a peace treaty. Billions or trillions of dollars consumed by military expenditure do not reappear when the guns fall silent.
War therefore possesses a strange arithmetic. Country A suffers an injury worth X and goes to war seeking redress. By the time the conflict ends, Country A may have suffered another ten X in casualties and destruction, while Country B has suffered twenty X. The original grievance may technically have been resolved, but everybody involved is substantially worse off.
This is precisely what Jefferson meant by saying that war "multiplies, instead of indemnifying losses." His formulation was being quoted approvingly in nineteenth-century arguments for international arbitration precisely because the problem was already understood: even successful wars frequently cost more than the grievance they were intended to remedy.
The First World War provides the almost perfect demonstration. Whatever legitimate grievances existed in Europe in 1914, virtually none justified the civilisation-scale destruction that followed. Millions died, economies were crippled, empires collapsed and revolutionary movements flourished amid the wreckage. The settlement then generated grievances of its own, contributing to conditions from which another and even more destructive European war emerged.
The original wrongs had not simply been redressed. They had reproduced. This is one reason political leaders so frequently miscalculate wars. The decision is normally made by comparing the expected military cost against the immediate political objective. Can we defeat the enemy? Can we seize the territory? Can we destroy the nuclear facilities? Can we remove the dictator? Those questions are necessary, but insufficient. The more important question is what happens afterwards.
Suppose a military operation successfully destroys an enemy regime. What replaces it? Suppose bombing destroys a nuclear programme. How quickly can it be rebuilt, and does the attack persuade the targeted country that acquiring nuclear weapons is now essential for survival? Suppose an invasion eliminates a terrorist organisation. Does the occupation subsequently generate another generation of recruits?
Military victory and political success are not the same thing. Iraq should have permanently destroyed the illusion that they are. Saddam Hussein's regime was removed with extraordinary speed in 2003. As a conventional military operation, the initial American campaign was impressive. But destroying the Iraqi state created consequences that extended far beyond removing Saddam: insurgency, sectarian violence, Iranian expansion, enormous American expenditure and eventually conditions exploited by Islamic State. The statue came down quickly. History continued.
Afghanistan offers an even harsher example. Western forces could overthrow the Taliban government in weeks. They could not manufacture a durable Western-style political order over the following twenty years. Thousands died, immense resources were consumed, and when Western forces finally departed, the Taliban returned to Kabul. Again, Jefferson's arithmetic asserted itself.
This does not mean those wars can be reduced to simplistic slogans about American aggression, nor does it mean nothing worthwhile was achieved. It means that war must be evaluated by its complete consequences rather than the first military objective appearing on a politician's briefing paper.
The same warning applies whenever commentators enthusiastically demand military action today. The question should never merely be whether the enemy deserves punishment. Governments and terrorist organisations frequently deserve punishment. The question is whether the proposed punishment will produce a world preferable to the one existing beforehand. That is a much harder test.
Iran illustrates the problem particularly well. There are powerful arguments for preventing a hostile theocratic regime from acquiring nuclear weapons. There are equally powerful reasons to oppose its support for terrorism and regional proxies. But even if military action destroys Iranian facilities and kills senior commanders, the calculation cannot stop there.
What happens to the Strait of Hormuz? What happens to global oil prices? What happens if Iranian proxies attack American bases? What happens if terrorism spreads outside the Middle East? What happens if the Iranian regime concludes that only possession of an actual nuclear arsenal can protect it from future attack? The first explosion is easy to imagine. The twentieth consequence is not.
This is where advocates of war often have an intellectual advantage over their critics. The military objective is concrete. Destroy the bridge. Sink the ship. Capture the city. Kill the terrorist leader. The consequences of doing so spread outward through political, economic and social systems that are vastly more complicated. The commander can tell you whether the target was destroyed. Nobody can tell you with comparable certainty what political world that destruction will create five years later.
War also generates interests in its continuation. Military bureaucracies expand. Defence contractors acquire enormous orders. Politicians become reluctant to admit that lives already lost may have achieved little. National prestige becomes attached to victory. Each casualty becomes an argument for continuing because otherwise previous casualties supposedly "died for nothing." The losses themselves consequently become reasons for risking additional losses.
Jefferson's observation is therefore not merely moral. It is an argument about complex systems. Violence introduces enormous new variables into an already unstable situation. Every bomb produces effects beyond its target. Every death creates relatives, memories and sometimes desires for revenge. Every destroyed institution creates a vacuum. Every sanction produces adaptations. Every alliance generates counter-alliances. This is why wars are notoriously easier to begin than to end.
None of this establishes absolute pacifism. There are circumstances in which refusing to fight produces greater losses than fighting. Had Britain simply accepted Nazi domination of Europe, peace would hardly have represented a morally superior outcome. A nation under invasion possesses both the right and practical necessity of defending itself.
The Jeffersonian principle instead creates a presumption against war rather than an absolute prohibition. Before choosing force, statesmen should have to demonstrate not merely that a wrong exists, nor merely that the enemy is wicked, nor even merely that military victory is achievable. They should demonstrate that the likely consequences of war are preferable to the likely consequences of restraint.
That is an enormously demanding standard. It should be. Human beings have an understandable desire to see wrongs punished. When nations are attacked, humiliated or threatened, the demand to "do something" becomes overwhelming. Military force offers the most dramatic something available. Aircraft launch, missiles streak across television screens and politicians appear suddenly decisive.
Diplomacy looks weak by comparison because successful diplomacy often produces no dramatic pictures at all. Yet restraint can require considerably more courage than retaliation. A statesman must sometimes endure accusations of weakness while calculating that tomorrow's consequences matter more than today's applause. He must distinguish between protecting genuine national interests and satisfying the emotional desire to strike back.
Jefferson understood the terrible asymmetry at the centre of warfare. Destruction can occur in seconds; reconstruction takes decades. A missile costing a few million dollars can destroy infrastructure worth hundreds of millions. A bullet can end a life that took twenty years to raise and educate. A political order painstakingly assembled over generations can disappear during several months of civil war.
War destroys accumulated capital, human, physical, institutional and moral, far faster than civilisation can recreate it. That is why the burden of proof must always rest with those proposing war. Sometimes they will meet that burden. Sometimes war really is the least terrible alternative available.
But history repeatedly vindicates Jefferson's warning. Nations go to war seeking compensation for one wrong and emerge carrying ten new ones. They seek security and manufacture enemies. They seek territory and inherit insurgencies. They seek vengeance and create another generation seeking vengeance in return.
War promises to settle accounts. Far more often, it merely adds another column of losses to the ledger.