James Madison warned us about the costs of war.
War comes with an extremely high price tag. According to the Cost of War Project by the Watson Institute at Brown University, the U.S. spent $2.26 trillion on the war in Afghanistan alone. That comes to over $300 million spent every single day over the span of two decades.
In 2018, the Watson Institute calculated that America’s “war on terror” had cost the equivalent of $23,000 per taxpayer.
But the average person has no sense of the cost of America’s neverending wars. That’s because the government primarily pays for its wars by borrowing money, effectively pushing the cost to future generations.
Imagine if every taxpayer had to write that $23,000 check.
We might reconsider perpetual war.
James Madison thought so.
In 1792, Madison argued that the cost of war should be borne by those who wage it.
He wrote that the best way to limit the number of wars would be to make the people pay the full cost immediately instead of financing them with debt and putting the onus on future generations to bear the cost. This would force politicians, and the population at large, to count the cost of war before rushing headlong into hostilities. Madison reasoned that if the people knew the actual cost of war and had to pony up the funds, it would reduce the number of wars. People would make a more concerted effort to resolve conflict peacefully.
Madison made this argument in a newspaper article responding to a plan offered by French philosopher Jean-Jacques Rousseau years earilier that was supposed to introduce “perpetual peace” in Europe.
As Madison summarized it, Rousseau’s plan involved a confederation of sovereigns, under a council of deputies. In practice, Rousseau was advocating for an international court and a league of states. This body would arbitrate external controversies among nations and guarantee their respective governments against internal revolutions. It sounds a lot like a blueprint for the United Nations.
Madison wrote that this plan would be impossible to execute “among governments which feel so many allurements to war.” He also predicted that such an international body would “perpetuate arbitrary power wherever it existed.”
Looking at the operation of the modern U.N. proves Madison was entirely correct.
More broadly, Madison viewed perpetual peace as a utopian dream. But he wasn’t criticizing those who quest for peace. In fact, Madison encouraged it.
“A universal and perpetual peace, it is to be feared, is in the catalogue of events, which will never exist but in the imaginations of visionary philosophers, or in the breasts of benevolent enthusiasts. It is still however true, that war contains so much folly, as well as wickedness, that much is to be hoped from the progress of reason; and if any thing is to be hoped, every thing ought to be tried.” [Emphasis added]
Madison’s issue was with a plan for peace that merely created another centralized political body and that ignored the realities of why wars start and how they are funded.
In Madison’s view, war powers should be kept out of the hands of individuals. He wrote war should “be declared by the authority of the people, whose toils and treasures are to support its burdens, instead of the government which is to reap its fruits.”
In the general distribution of powers, we find that of declaring war expressly vested in the congress, where every other legislative power is declared to be vested; and without any other qualification than what is common to every other legislative act. The constitutional idea of this power would seem then clearly to be, that it is of a legislative and not an executive nature…
Those who are to conduct a war cannot in the nature of things, be proper or safe judges, whether a war ought to be commenced, continued, or concluded. They are barred from the latter functions by a great principle in free government, analogous to that which separates the sword from the purse, or the power of executing from the power of enacting laws.
Beyond this separation of powers, Madison wrote in his 1792 newspaper article that “each generation should be made to bear the burden of its own wars, instead of carrying them on, at the expence of other generations.” Furthermore, Madison proposed that “war taxes” should be levied in such a way as to make it clear what those dollars are paying for.
“Each generation should not only bear its own burdens, but that the taxes composing them, should include a due proportion of such as by their direct operation keep the people awake, along with those, which being wrapped up in other payments, may leave them asleep, to misapplications of their money.”
Madison reasoned that “were a nation to impose such restraints on itself, avarice [extreme greed for wealth or material gain] would be sure to calculate the expences of ambition.”
“In the equipoise [balance of forces or interests] of these passions, reason would be free to decide for the public good; and an ample reward would accrue to the state, first, from the avoidance of all its wars of folly, secondly, from the vigor of its unwasted resources for wars of necessity and defence. Were all nations to follow the example, the reward would be doubled to each; and the temple of Janus  might be shut, never to be opened more.”
Madison’s plan is rooted in common sense. People will quickly spend other people’s money, but they will tend to be frugal with their own. If the people had to pay for their own wars, they would be far less likely to cheerlead their representatives when they drag them into hostilities. They would be more likely to hold the political class accountable. And ultimately we’d enjoy more years of peace.
Rousseau was dead by the time Madison wrote his article. Madison reason that if Rousseau was still alive, he perhaps would come to a different conclusion.
“After tracing the past frequency of wars to a will in the government independent of the will of the people; to the practice by each generation of taxing the principal of its debts on future generations; and to the facility with which each generation is seduced into assumptions of the interest, by the deceptive species of taxes which pay it; he would contemplate, in a reform of every government subjecting its will to that of the people, in a subjection of each generation to the payment of its own debts, and in a substitution of a more palpable, in place of an imperceptible mode of paying them, the only hope of UNIVERSAL AND PERPETUAL PEACE.”
 In ancient Rome, the gates of the temple of Janus (the god of beginnings) were closed during periods of peace and opened in times of war.