Maybe war has declined because people value their lives more now

"The past is a foreign country; they do things differently there." — LP Hartley

In my last post, I argued against a possible explanation for the recent decline in war: that wars have become more destructive, and thus more costly to wage. This explanation doesn’t work. Often, pre-modern wars were devastating.¹ Rome lost a fourth of its military-age population in the first three years of the Second Punic War alone. But this didn’t reduce Rome’s appetite for war.² Be it ancient Greek and Indian wars, Mongol invasions or the Second World War, losing had steep costs. But war continued.

A better explanation is that returns on peace have risen. Interstate trade has become extremely valuable, especially between great powers (who are likely to have the most destructive wars in the first place). Damaging a state that supplies valuable resources can hurt more than it helps.

A compelling explanation I’ve seen less often is: wars have become more costly. But not in the raw number of casualties. Maybe people just value their lives more in the modern age.

Why would we think so? Here are a few reasons.

Increased life expectancy

Via Our World in Data

As late as 1870, the global average life expectancy was under 30 years. Today, it has more than doubled to 71 years, and just four countries have a life expectancy below 55 years. 

People were simply putting less on the line by going to war in the pre-modern era. If the war didn’t kill them, something else would in likely a decade or less. Their death would also be painful if it was due to disease or malnourishment, or if they died as a non-combatant in a war (perhaps the same one they chose not to fight in?).

BTW, this also suggests that ranking historical atrocities by lives lost may be a bit misguided. This way, when you divide the casualties in a particular war by the global population at the time, many historical atrocities with fewer raw casualties than modern atrocities turn out to be “bloodier” (because they killed a larger fraction of the global population). With this adjustment, the five greatest atrocities are, in order, the An Lushan rebellion (which ranks 4th in raw casualties), the Mongol conquests (3rd), the mideast slave trade (9th), the fall of the Ming dynasty (5th), and the fall of Rome (15th). The Second World War, which has the highest death toll of any recorded atrocity, sinks to 9th place.³

Perhaps the relevant metric is life years lost, not lives. This could result in modern conflicts that killed a lower proportion of the global population being considered the “bloodiest”, because they caused more loss of life in an important sense.

Increased happiness

While we certainly don’t have subjective wellbeing survey results from the pre-modern era, we have a few reasons to think that people are generally happier today (and therefore, probably less willing to put their lives on the line in a war).

First, modern people enjoy better economic outcomes. The canonical example of this is lighting, from William Nordhaus’ famous paper. In Babylon, a day’s hard work would produce enough to light a room for ten minutes. By the end of the 20th century, the same amount of labor could buy ten years of light.⁴

The inflation-adjusted price of light in cents per 1000 lumen-hours, via William Nordhaus’ paper

But this still doesn’t take into account goods that pre-modern people couldn’t buy at any price. Charlemagne couldn’t get antibiotics to treat his painful and ultimately fatal lung infection for the combined fortunes of united Europe. If you wanted to send a message or travel from one side of the world to another in less than a day, you were simply out of luck. A Spotify subscription and a pair of headphones can bring you instant world-class music from a dizzying array of genres—a luxury out of reach for even kings of yore. 

Many modern combatants leave behind a life that would be considered royal by pre-modern standards when they go to war.

In fact, since pre-modern war often brought widespread hunger, guaranteed army rations and potential loot could sometimes even have been a better deal than starving as a non-combatant.

Second, we experience the anguish of losing a loved one much less often. 

We saw in the previous section that life expectancy was below 30 years until the late 20th century. 

Child mortality was just as dismal. As the chart below shows, death rates across 43 historical cultures were strikingly similar: every fourth newborn died in its first year of life. One in two died before reaching the age of 15. Today, the global infant and child mortality rates are 2.9% and 4.6% respectively—still awful, but far better. 

Via Our World in Data

Larger costs to kin if we die

Labor in the past didn’t produce amazing economic returns. GDP per capita was low and basically constant for most of the last twenty centuries. Individual income wasn’t far above subsistence level.

Probably the best-known chart in all of economics, via Our World in Data

Only in the last couple hundred years has economic growth exploded. The average person in the UK today has a higher income in two weeks than an average person in the past had in an entire year. 

This means that pre-modern families didn’t lose out on huge sources of income if someone from their family died fighting in a war. In fact, in times of significant hardship or widespread joblessness (such as during a war), it could have been in the selfish best interests of the family to send members who were consuming more than they were producing to war. Particularly if the family were required by social pressure or law to send conscripts. 

Reduced belief in an afterlife

If fewer modern people believe in life after death, they may attach more value to their lives and be less willing to risk death fighting a war. 

Do fewer modern people believe in an afterlife?

According to Pew, 80% of US adults believe in a potentially happy afterlife—73% in heaven, and 7% in neither heaven nor hell but an afterlife of some sort. The US numbers are unusually high though.

Belief in an afterlife is much less common in Europe: according to the World Values Survey, 44% in Great Britain, and 30-45% in most European countries. China is the lowest of any country surveyed, at just over 10%. Religious unaffiliation—which I’d expect to map closely with a reduced belief in an afterlife—is on the rise in the US.

In contrast, belief in the afterlife features prominently in almost all ancient religions, and folk and major religions before the Industrial Revolution. Of course, this isn’t to say that everyone in pre-modern societies believed in an afterlife. But I’d be surprised if the Enlightenment and the Scientific Revolution haven’t meaningfully increased skepticism against religious and spiritual claims.

It’s also entirely possible that people believe in an afterlife with less conviction now in a way that wouldn’t be captured by Pew and World Values Surveys’ results. A person who thinks heaven is a weak but non-trivial possibility and an afterlife believer who is much more convinced would both answer “yes” to “do you believe in heaven?”. It seems likely to me that pre-modern afterlife believers were more convinced of their position than modern ones are, as they hadn’t been exposed to the now-commonly accepted scientific dogma against life after death. 

Summary

Today, people lead longer and happier lives. Their survival is more economically beneficial to their kin. Fewer people believe in an afterlife, and less fervently than their ancestors did—hence, they probably value their time in the mortal plane more.

These factors suggest that people today should be more unwilling to fight in a war today, and could partially explain why, as Robert O’Connell writes in Of Arms and Men, “war has fallen upon hard times.”

1. The “intuition” for modern wars being more destructive is that technology has made weapons more lethal. This reasoning is faulty, though—improvements in technology also mean better defense, like faster vehicles and stronger armor. Further, most casualties in modern atrocities such as the Rwanda genocide and the World Wars weren’t due to some advanced military technology, but intentional starvation, exposure to the elements and crude mass executions. Both these arguments are from Azar Gat’s paper.

2. This example is from Azar Gat’s paper.

3. Pinker, Steven. The Better Angels of Our Nature: Why Violence Has Declined. New York, Penguin Books, 2011, p. 195.

4. This example is from Tim Harford’s article.