Decades ago, when I began teaching international history, I used to ask students if they thought it was possible for nations to end their fighting of wars against one another.

Their responses varied. But the more pessimistic conclusions were sometimes tempered by the contention that, if the world’s nations faced a common foe, such as an invasion from another planet, this would finally pull them together.

I was reminded of this on March 23, when the UN Secretary-General, António Guterres, called for “an immediate global ceasefire.” The time had come, he said, to “end the sickness of war and fight the disease that is ravaging our world.” A UN summary noted that the Secretary-General had “urged warring parties across the world to lay down their weapons in support of the bigger battle against COVID-19: the common enemy that is now threatening all of humankind.”

If human beings behaved rationally, they would certainly recognize their common enemy and back this proposal.

After all, why not work cooperatively to save humanity from massive global death and economic collapse rather than continue to devote $1.8 trillion a year to waging wars and engaging in vast military buildups with the goal of slaughtering one another?

The U.S. government alone is currently spending a record $738 billion a year on its ever-growing military machine — considerably more than it allocates every year for health, education, and all other civilian services. How about using these enormous resources, now earmarked for war and war preparations, to meet the needs of its own people, such as coping with the coronavirus pandemic?

And surely other heavily-armed governments, currently shoveling the human and economic wealth of their nations down the rathole of war, would also benefit by a reordering of their priorities.

Furthermore, with the world swept by a deadly pandemic — and maybe only the first of many in the coming decades — how are nations going to maintain the necessary armed forces to fight wars? Soldiers, like sailors, live in close proximity with one another and, as a result, their ranks are likely to be decimated by disease.

As illustrated by the recent dismissal from command of a U.S. Navy captain who warned of the spread of the coronavirus on his aircraft carrier, top military officials are likely to resist recognizing the deteriorating health of their military personnel. But that willful ignorance won’t put an effective combat or military occupation force in the field. It might even lead to widespread resistance and revolts among the troops, as disease and death sweep through their cramped barracks and ships’ sleeping quarters.

Nevertheless, as history shows us, we are not living in a thoroughly rational world.

Nations — and, before their existence, competing territories — have been squandering human and economic resources on war and war preparations for millennia. Even 75 years after the obliteration of Hiroshima and Nagasaki with atomic bombs, nations continue to arm themselves with roughly 14,000 nuclear weapons, preparing for — and sometimes threatening — a nuclear war that will destroy most life on earth.

Moreover, the coronavirus pandemic might be strengthening authoritarian political tendencies that, traditionally, have gone hand-in-hand with militarism. Recognizing the fear and panic that are already gripping the general public, power-hungry government officials are using the crisis to proclaim a state of emergency and cut back political freedom.

In Hungary, Prime Minister Viktor Orbàn convinced parliament, controlled by his party, to cancel all elections, suspend its ability to legislate, and give him the right to rule by decree indefinitely. In the United States, Donald Trump, after initially making light of the pandemic, did a total reversal — declaring “a national emergency” and reinventing himself as a “war president.”

Recently, under cover of the coronavirus crisis, Trump has escalated his military threats against other nations, ordering stepped-up action by the U.S. forces forces that risks war with Iran and, also, portends a U.S. military attack upon Venezuela.

In short, the jury is still out on whether the coronavirus pandemic will weaken or strengthen war and militarism. Much will depend on what the public of heavily-armed nations will demand. Will they press for a reorientation of their countries’ priorities from waging war to meeting human needs?

Or, despite the enormous challenges posed by the disease pandemic, will they once again rally behind their flag-waving rulers — all too often unscrupulous and incompetent — and pour their blood and treasure into war?

Given the world’s long history of violent international conflict, it would be foolish to bet on humanity turning over a new leaf.

But, on the other hand, there have been occasions when human beings have worked together to solve their common problems. Perhaps they will do so again.

Dr. Lawrence Wittner, syndicated by PeaceVoice, is Professor of History emeritus at SUNY/Albany and the author of “Confronting the Bomb” (Stanford University Press).