Nobody has ever fought a war over the oxygen in the air because there's plenty of oxygen to go around. We fight over things that are scarce and valuable. Historically, most wars have been fought over land and people. If you win you get to force your subjects to collect raw materials from the land. Sometimes these raw materials are mineral resources. Historically, most slaves have been forced to cultivate food.

It's hard to comprehend how important food staples used to be. In Edo Japan, wealth was measured in koku (石). One koku is (in theory) enough rice to feed one man for one year. The amount of koku a daimyo controlled was basically how many people he owned because a region's food staple production determined its carrying capacity and the human population grew until it hit carrying capacity. In other words, we bred until we were on the edge of starving to death. Most wars have ultimately been fought over land because land determines food production and food production was a matter of life and death.

My grandfather, who grew up in Taiwan before the green revolution, was too poor to afford rice. He ate sweet potatoes instead.

The green revolution of the 1950s and the 1960s increased food production faster than our population growth. On the Chinese version of TikTok[1] there's a video of a guy eating a bowl of white rice with a spoonful of soy sauce. The comments are all of people feeling sorry for him. We have so much food these days that eating nothing but rice makes you surprisingly poor even by Chinese standards.

World War II ended in 1945—right before the green revolution. There has been no direct war between major world powers between then and now. I don't think this is a coincidence. Wars are usually about land and land is usually about food production and food production skyrocketed in the decades after World War II. (Birth control became widely adopted around the same time too.)

We still have small wars. We fight over oil and ideologies. But cars and capitalism aren't as important as food production. Fighting wars over food is stupid when food is cheap. Less fighting over food means less fighting overall. Countries being at peace with each other set the conditions for us to build more complex, interdependent trade networks. I think the idea that we're all human beings, regardless of our race, religion, sex and country of origin gained increasing power because cooperation is a winning strategy when there is enough to go around.

I predict that if per capita food production returns to the levels of 1914 1776[2] then so will humankind's ethics.

  1. 抖音 came first. Technically, TikTok is the American version of 抖音. ↩︎

  2. Edit: See comment by Kaj_Sotala. ↩︎

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In 1821, Japan was a feudal isolationist polity.

In 1921, Japan was an industrial Western-style empire.

In 2021, Japan is a post-industrial, democratic, liberalish nation-state.

What got Japan to break out of its isolation? The United States threatened to burn down its capitol.

What got Japan to abandon its empire? The United States actually did burn down its capitol. B-29s dropped firebombs on defenseless cities full of women, children and the elderly. 100,000 civilians were killed in Tokyo alone.

This isn't a criticism of the United States. Between Nazi Germany, the Japanese Empire, the Soviet Union and the United States, the United States was the closest thing there was to "the good guys".

My great grandfather served on the US Merchant Marine. His job was to operate ships carrying weapons and equipment from the United States to Europe while dodging U-boats. After Germany surrendered, he wanted to drop punitive atomic bombs on German cities.

I understand his perspective. He was a Jew.

The Advance of Modern Civilization

"It took centuries for science to dawn over the Muggle world, it only happened slowly, but the stronger science got, the further that sort of hatred retreated." Harry's voice was quiet, now. "I don't know exactly why it worked that way, but that's how it happened historically. As though there's something in science like the shine of the Patronus Charm, driving back all sorts of darkness and madness, not right away, but it seems to follow wherever science goes."

―Chapter 47 of Harry Potter and the Methods of Rationality by Eliezar Yudkowsky

Harry James Potter-Evans-Verres claims that the advance of science reduced hatred. We had science in 1945. But did we really have less hatred then in, say, 1845?

Yes. Yes we did. Slavery was legal in the United States in 1845. It ended because the industrial capacity of the Union crushed the plantation-based economy of the Confederacy. Just like the industrial capacity of the United States and manpower of the Soviet Union crushed their enemies in World War II.

Are you noticing the pattern yet? Modern industrial societies produce so much of everything they outcompete slave-based societies[1] based around raw materials.

The Enlightenment, that was what it was called in the Muggle world. It has something to do with seeking the truth, I think... with being able to change your mind from what you grew up believing... with thinking logically, realizing that there's no reason to hate someone because their skin is a different color, just like there's no reason to hate Hermione Granger... or maybe there's something to it that even I don't understand. But the Enlightenment is something that you and I belong to now, both of us. Fixing Slytherin House is just one of the things we have to do.

―Harry James Potter-Evans-Verres in Chapter 47 of Harry Potter and the Methods of Rationality by Eliezar Yudkowsky

Harry James Potter-Evans-Verres believes hatred decreased because Enlightenment ideals encouraged us to change our minds. I claim hatred decreased because the material bounty of technological advancement increased the competitive advantage of cooperation compared to violence.

Is there a way to test this? To do so we'd need to examine a nation where Enlightenment ideals came before industrialization or a nation where industrialization came before Enlightenment ideals. History provides us with both.

  • Meiji Japan industrialized without subscribing to Enlightenment ideals.
  • The United States was founded with Enlightenment ideals before it industrialized.

What happened?

  • The United States exterminated the Native Americans. The United States' universalist ideals took hold after it industrialized, not before. It had people in concentration camps all the way up to 1945.
  • Meiji Japan comitted atrocity after atrocity even after it industrialized, all the way up to 1945.
  • Meiji Japan abolished the samurai class.
  • The United States abolished slavery (eventually).

The ultimate strategic objectives for Japan's and the United States' East Asian conquests were identical. They both wanted buffer states against the Soviet Union and access to raw materials. If Japan and the United States had such similar interests then why did the United States build up its conquests while Japan enslaved them? Japan did industrialize Korea and Manchuria. The United States did a better job because it had 5× the industrial capacity of the Japanese Empire at the Japanese Empire's peak. The United States had so much wheat it shipped the surplus to starving occupied Japan for free. Japanese cuisine is dominated by rice. The United States shipped so much wheat to Japan it basically created a national dish. Ramen noodles are popular in Japan today because they needed a way to eat all that wheat.

It's hard to hate other people for hogging all the wheat when there is too much wheat to go around. We have so much corn we ferment it into ethanol so we can burn it[2].

Subjugating other people requires coordination. The more of value we produce, the less it's worthwhile to spend that coordination extracting tiny bits of material value from other people. It you want to bring hatred to modern lows and equality to modern highs, it's not enough just to industrialize a little. You have to industrialize a nation so much its people can't be bothered to oppress others because they have better things to do with their time. Hatred has decreased because we live in the golden age of all golden ages.

  1. This post is focused on conflicts between civilizations. I'm ignoring hunter-gatherers and pastoralists. ↩︎

  2. Technically, there is an even stronger causation in the opposite direction: we grow so much corn because we can burn it. The economics of biofuels are beyond the scope of this comment. ↩︎

I thought what broke Japan was a credible threat of being nuked rather than the firebombings

Worth noting that Northern states abolished slavery long before industrialization. Perhaps even more striking, the British Empire (mostly) abolished slavery during the peak of its profitability. In both cases (and many others across the world), moral arguments seem to have played a very large role.

The historian Bret Devereaux argues that most wars were indeed fought over land, but that fighting over land had already became unprofitable by World War 1, and wars kept happening anyway because people's intuitions and institutions had not caught up:

As Azar Gat notes in War in Human Civilization (2006), for most of human history, war ‘paid,’ at least for the elites who made decisions. In pre-industrial societies, returns to capital investment were very low. They could – and did – build roads and infrastructure, irrigation systems and the like, but the production multiplier for such investments was fairly low. For antiquity, the Roman Empire probably represents close to the best that could be achieved with such capital investments and one estimate, by Richard Saller, puts the total gains per capita at perhaps 25% over three centuries (a very rough estimate, but focus on the implied scale here; the real number could be 15% or 30%, but it absolutely isn’t 1000% or 100% or even probably 50%).

But returns to violent land acquisition were very, very high. In those same three centuries, the Romans probably increased the productive capacity of their empire by conquest 1,200% (note that’s a comma, not a dot!), going from an Italian empire of perhaps 5,000,000 to a Mediterranean empire in excess of 60,000,000 (and because productivity per capita was so relatively insensitive to infrastructure investments, we can on some level extrapolate production straight out of population here in a way that we couldn’t discussing the modern world). Consequently, the ‘returns to warfare’ – if you won – were much higher than returns to peace. The largest and most prosperous states tended to become the largest and most prosperous states through lots of warfare and they tended to stay that way through even more of it.

This naturally produced a lot of very powerful incentives towards militarism in societies. Indeed, Gat argues (and I agree) that the state itself appears to have emerged as a stage in this competitive-militarism contest where the societies which were best at militarizing itself and coordinating those resources survived and aggregated new resources to themselves in conflict; everyone else could imitate or die (technically ‘or suffer state-extinction’ with most of the actual people being subjugated to the new states and later empires). Those incentives produce exactly the behaviors we see in EU4 and in the early-game of VickyII where the most successful states are the ones that are rapaciously expansionist. And this makes a lot of sense if you think about the really basic energy economy of these societies: nearly all of the energy they are using comes from the land, either in the form of crops grown to feed either humans or animals who then do work with that energy. Of course small amounts of wind and water power were used, but only small amounts.

As Gat notes, the industrial revolution changed this, breaking the agricultural energy economy. Suddenly it was possible, with steam power and machines, to use other kinds of energy (initially, burning coal) to do work (more than just heating things) – for the first time, societies could radically increase the amount of energy they could dispose of without expanding. Consequently – as we’ve seen – returns to infrastructure and other capital development suddenly became much higher. At the same time, these new industrial technologies made warfare much more destructive precisely because the societies doing the warfare now had at their disposal far larger amounts of energy. Industrial processes not only made explosives possible, they also enabled such explosives to be produced in tremendous quantities, creating massive, hyper-destructive armies. Those armies were so destructive, they tended to destroy the sort of now-very-valuable mechanical infrastructure of these new industrial economies; they made the land they acquired less valuable by acquiring it. So even as what we might term ‘returns to capital’ were going wildly up, the costs of war were also increasing, which mean that ‘returns to warfare’ were going down for the first time in history.

It’s not clear exactly where the two lines cross, but it seems abundantly clear that for the most developed economies, this happened sometime before 1914 because it is almost impossible to argue that anything that could have possibly been won in the First World War could have ever – even on the cynical terms of the competitive militarism of the pre-industrial world – been worth the expenditure in blood and treasure.

At the same time, Gat notes that human societies didn’t suddenly reinvent themselves in 1900. We have all of these institutions, these social habits, these values, these works of literature and culture which were produced to help our societies survive in the environment of competitive militarism that existed before 1900. It is hard to stress the magnitude of the shift Gat is talking about here – taking the modern state, the most efficient violence-machine ever developed by humans – and putting it in a world where war is maladaptive is roughly like dropping a polar bear in the Serengeti. Everything that bear has ever learned is suddenly pretty useless or actively harmful. So societies entered this brave new industrial world with a whole lot of habits and institutions designed to push them towards war because war used to be how one profited and survived.

This is a good point. My year of 1914 was too late. I failed to account for cultural inertia. I have changed the year to 1776.

This seems probably right.

I’m interested in the obvious followup questions of “how hard does this check out over more than 2 examples? How strong is the effect size of surplus food / how much food do you need? Do you need enlightenment memes separately from the food? Is food abundance sufficient or do you also need other kinds of abundance?”

Republican Rome is the example I know best, sorta fits?

Rome fought a lot of wars, and they were usually pretty extractive: sometimes total wars in which the entire losing side was killed or enslaved, other times wars of conquest in which the losing states were basically left intact but made to give tribute (usually money and/or soldiers for the legions).  They definitely relied on  captured foreigners to work their farms, especially in Sicily where it was hard to escape, and they got so rich from tribute that they eliminated most taxes on citizens in the 160s BC.

It's not clear that Rome was short of food and slaves when it started those wars, though.  If anything, they sometimes had the opposite problem: around 50 BC so many farmers and farmers' sons were being recruited into the legions that Italian farmland wasn't being used well.  I think the popular consensus is that a lot of warfare and especially enslavement was a principal-agent issue: Roman generals were required by custom to split any captured booty with their soldiers, but were allowed to keep all the profits from slave-trading for themselves.  Enslaving a tribe of defeated Gauls was a great way to get rich, and you needed to be rich to advance in Roman politics.

To summarize, Roman warfare during the republic was definitely essential to Roman food security, but they got into a lot more wars than you'd predict from that factor alone.

Clear exceptions to the rule include the Social war (basically an Italian civil war), the third Punic war (eliminating the existential threat of Carthage), and some of Caesar's post-dictatorship adventures (civil war again).

This is deeply unconvincing. We didn't have a great power war in the 60s or the 70s because that would have meant nuclear war. High-level US government officials in internal documents describe Russia as an existential threat. Russian government documents, as I understand it, reflect terror of American willingness to use nukes. We haven't had a war between the US and China yet, but estimates of that holding true over the next five years are less confident than I'd like.

"Most wars have ultimately been fought over land because land determines food production and food production was a matter of life and death."

It seems like you're explaining the actions of kings with the preferences of peasants (and I am very unconvinced that a victorious war was better for the average peasant than peace), and I don't see that as particularly persuasive. 

It seems like you're explaining the actions of kings with the preferences of peasants (and I am very unconvinced that a victorious war was better for the average peasant than peace), and I don't see that as particularly persuasive.

Starving peasants revolt. Kings don't like revolts. Using starving peasants as soldiers to conquer new land is a way to divert peasant revolt by promising them the new land. And the king kills 2 birds with 1 stone, since starving peasants die killing neighbouring rivals. I'm not certain that's how it happens, but it's plausible and it solves all your qualms.

Keep in mind - oil is food production, as much or more than land is.   Moving workers to the right spots, running irrigation pumps, machinery, etc.  is all fueled by oil.  As is moving raw food to processing areas, and then to the actual hungry people.

In-group ethics don't have to be the same as between-group ethics. For most of history they weren't. Universal ethics is a new and WEIRD idea. If a society exists in a state of plenty, its members can behave in a nice, genteel manner to each other, even if they are viciously exploiting other societies to maintain their lifestyle.


World War II ended in 1945—right before the green revolution. There has been no direct war between major world powers between then and now. I don't think this is a coincidence.

Although I agree with the overarching point, I don't think this particular line of argument holds up. For instance, the invention of the Haber-Bosch process did nothing to stop the two bloodiest wars in human history from occurring almost immediately afterwards.

War happens when there's not enough food to feed the people in a nation. Another way of saying it would be that war happens where there's too many people in a nation to feed. Most individuals value breeding as a noble goal, and that's respectable. But nations encourage breeding because of competitive reasons: to have expandable soldiers for war (military compatition), to increase production of goods (trade/cultural competition), to support modernization (technological competition). New humans are like missiles. I predict human population will not stabilize by themselves. 1 of 3 things will happen:

  • human population will grow over 10 billions
  • there will be human non-proliferation treaties the like of nuclear weapon non-proliferation treaties (prefered but unlikely)
  • large, bad losses of already existing life (war, crime, famine, disease)

I predict that if per capita food production returns to the levels of 1914 then so will humankind's ethics.

UK will be testing this theory shortly.