Paul K. Chappell, author of The Art of Waging Peace, delivers his lecture “Why World Peace is Possible” Friday, Aug. 19, 2016 in the Hall of Philosophy.

In 1878, Floyd Hatfield may or may not have stolen Randolph McCoy’s hog. There was a trial and Hatfield was acquitted on the testimony of Bill Staton, a McCoy married to a Hatfield. Two years later, Randolph’s nephews brutally murdered Staton and by 1888, more than 12 people had been killed, a house burned to the ground and seven Hatfields and McCoys sentenced to life in prison. More than a century later, the names Hatfield and McCoy remain synonymous in America with the senseless violence of a bygone era.

But should they be? The question is not whether this particular violence war senseless but whether it was unique. Friday at the Hall of Philosophy, Capt. Paul K. Chappell argued that a sense of disrespect — e.g. you took something from me — lies behind every single war. Eventually, Chappell said, people will learn other means of resolving conflict, ending nuclear weapons and environmental destruction the same way humanity has dramatically reduced violence.

“There are two possible futures: First, 5,000 years from now, people will look back on us and say, ‘Can you believe we used to wage war, use nuclear weapons and destroy the environment?’ ” said Chappell, author of  The Art of Waging Peace. “Second is 5,000 years from now, the world is in ruin and there are no humans”

Chappell tried to prove that violence could be overcome by highlighting the unbelievable progress humans have made in other areas.

He began with a thought experiment: Imagine you are transported to medieval England and your task is to convince the people that all white men should vote. Your first obstacle is not about voting, but about convincing Europeans that “white people” is an actual identifiable group. For one, these people were not white, but fairly brown from working in the sun all day. But more importantly, it would have been absurd to medieval Britons that they were the same and should have equal rights as other Europeans. The British regarded the Irish as subhuman. At the time it was legal for a British man to rape and murder Irish people with impunity. Up until World War I, Chappell said, the French saw the Germans as gorillas.

“Now what would happen today if a French politician called a German subhuman?” Chappell said. “The circle of who we consider human is much wider than ever before, and it must become wider, but we’ve made progress.”

The second problem is that the people would have considered voting a sin because kings were ordained by God, Chappell said. Today, democracy is so popular that even dictatorships such as Russia hold “elections.”

Second thought experiment: Go to a Harvard classroom in 1800 and convince the students that women should have the right to vote. Today, even places without women’s rights have women’s rights movements, but at the turn of the 19th century, not even women believed women should have right to vote.

This belief was undergirded by the myth that women were intellectually inferior and that their minds could not handle the responsibilities of voting, going to college and owning property. It’s obviously untrue today, Chappell said, but in the 19th century it was science. Even Darwin argued it.

Chappell continued with thought experiments for proving animal sacrifice and slavery wrong.

“What if we are just like those people? What if we are also very wrong about other issues?” Chappell said. “What if people in the future will look at us the way we look at people who supported slavery, thought the Irish were subhuman and supported animal sacrifice?”

The big myth today is that humans are naturally violent, Chappell said, and therefore war can never be stopped. No one says that ebola, cholera and other illnesses are just human nature, Chappell said, but they do about violence.

But if humans are naturally violent, Chappell asked, then why does violence inflict such trauma on the human mind?

“If humans are naturally violent, war would make people better mentally healthy,” Chappell said.

Chappell quoted a military study by psychiatrists Roy Swank and Walter Marchand that found 98 percent of soldiers sustained trauma after 60 days of continuous day-night combat. The other two percent are already psychopaths, he said. It’s why the Army rotates troops and gives soldiers days off.

Even inflicting violence is traumatizing, Chappell said. He gave a chilling thought experiment: Imagine you have to spend an entire day with a 5-year-old girl in a park, learning everything about her and her hopes and dreams. Then at the end of the day, you have to look her in the eye and bash her skull in with a hammer.

That trauma, however, reduces if you don’t have to look her in the eye, Chappell said. It reduces more if you shoot her with a rifle from 300 feet, Chappell said, and even more if you drop bombs from thousands of feet in the air. It’s a familiar argument for those following gun-control debates, as advocates argue that shooting someone from far away with a click makes it easier to kill them than, say, having to deliberately stab someone inches away from you

“The war system is able to create all these forms of distance to reduce the amount of people traumatized,” Chappell said.

The son of a Korean War veteran traumatized by his experience, Chappell said, was extremely rageful and violent as a kid. He learned to deal with it in part through martial arts, which teaches respect for everyone, including your opponent. The reason for this, Chappell said, is that all violence comes out of a feeling of disrespect and respecting your enemy can resolve conflict before it starts.

It’s the reason everyone reveres Nelson Mandela, Martin Luther King Jr. and Malala Yousafzai. Mandela respected his prison guards, and Yousafzai her shooters.

“They get their moral authority from their ability to convey respect,” Chappell said.

Listening is the best path toward showing respect, Chappell said, and if everyone did more of it, both international and civilian violence could be dramatically reduced.

“In all of human history I don’t think anyone has seriously said, ‘I can’t stand it when people listen to me,’ ” Chappell said.