If we want peace, stop the arms trade.

“Si vis pacem, para bellum”. "If you want peace, prepare for war" attributed to a Roman military writer Flavius Vegetius Renatus circa 375 AD.

This saying is generally accepted without criticism. But is it true?

Take suicide. The impulse to suicide is widespread, but the method is situation specific. For instance, in Bristol, people living nearer the suspension bridge were shown to be more at risk, and suicide rates dropped when barriers were erected. So, behaviour depends on two factors: desire and availability of an instrument. The same goes for death by shooting. Americans have easy access to guns, so, surprise surprise, they have high death rates by shooting.

By building up arms, politicians make it more likely that they will be used. It is in the interests of arms manufacturers to have wars, because that creates demand for their products.

If the Vegetius saying was true, the USA would be the most peaceable nation on earth, since it spends as much as the rest of the world combines. It is clearly not the most peaceable nation on earth, in fact the reverse is true.

I cannot find the source, but there is a story of two tribes who had a tradition of warring against each other. It was fairly ritualised, carried out on a regular annual basis, using clubs. A kind of deadly annual sports competition. Someone should have introduced them to football, but instead, they sold them a batch of machine guns and ammunition. Instead of deaths in single figures, the tribes wiped each other out.

True or not, the story shows how improving technology makes war more deadly. This is not to idealise swords and arrows, and the machete can kill you just as dead as the AK 47, but the machete is labour intensive, less productive.

Let's do a thought experiment. Take two countries, A and B, who dislike each other. An arms salesman goes to a country A and sells arms. He then goes to B and tells them that A has bought arms, so they need to defend themselves. B buys arms. And so on. An arms race is a mutually enforcing system.

This has relevance to Gaza. Israel and Hamas were both prepared for war. They got it. Now they have set the stage for yet more war.

Vegetius was wrong. If we want peace, we have to stop arming ourselves, stop selling arms into conflict areas, and start working to secure justice and sustainable economic systems.