# A Theory of Equilibrium in the Offense-Defense Balance

The offense-defense balance is a concept that compares how easy it is to protect vs conquer or destroy resources. For example, autonomous weapons and AI systems might make attacks easier and more scalable compared to defensive measures. The balance matters because when offense has the advantage, it can create instability and increase the likelihood of conflict.

I claim that worries over a massively upset offense-defense balance make the same mistake as peak oil apocalypse prophecies.

### Peak Oil

Peak oil hysteria was seeded in the environmentalism and energy crisis of the 1970s and reached its apogee in the early 2000s with a flood of books, documentaries, and movements predicting civilizational collapse.

In some ways, the predictions of peak oil prophets did come true. Oil prices rose to an all-time [peak in 2008](https://www.macrotrends.net/1369/crude-oil-price-history-chart), and [oil consumption](https://ourworldindata.org/grapher/oil-consumption-by-country?tab=chart&country=~USA) in the US reached its peak around the same time. Few, if any, of the forecasted societal or economic collapses came to fruition though.

The problem with the peak oil predictions was a selective extrapolation of some trends, while holding the adaptation of others constant. They projected rising oil prices and squabbles over the remaining finite supply that would force more and more uses for oil to shut down, but they didn’t project the new substitutes and oil sources that these high prices would create.

When oil prices rise from $100 to $200 a barrel, it doesn’t double everyone’s energy costs. $200 oil prices don’t force all plastic manufacturers to pay $200 for their chemical inputs, for example. They force them to substitute petroleum and use $150 dollars of vegetable oil instead. The new $200 price is an *upper bound* on what previous oil consumers pay after the price increase. Any consumers with substitutes that cost less than $200 will use those instead. So even in the most extreme world where oil runs out, most oil consumers aren’t faced with infinite costs and forced to shut down. Instead, they are only forced to pay for their next best substitute.

### Offense-Defense Balance

As an example of how this mistake applies to the offense-defense balance, consider the offense-defense balance of presidential assassination. In the 19th century, guns were inaccurate at long ranges, so assassins needed to get close. Security used this defensive advantage to protect the president, but some assassins did slip through. Accurate, long range rifles are a massive upset to the offense-defense balance of presidential assassinations. Instead of needing to sneak up on the president in a theatre, you could sit half a kilometer away and take shots from there. These accurate guns are cheap and accessible.

But it would be a mistake to predict some large increase in the rate of presidential assassination. That prediction only makes sense if you extrapolate one trend in offensive capabilities, but hold everyone else’s adaptation constant. A rise in the offensive capability of assassins doesn’t force the secret service to accept a higher rate of presidential assassination. They are just forced to buy [The Beast](https://en.wikipedia.org/wiki/Presidential_state_car_(United_States)) and put them behind glass.

Applying this to the future, consider drone-powered assassination. Assassin drones with bombs strapped to them will be small, fast, cheap, and potentially autonomous. This will make it easier to attempt to assassinate world leaders, but again it would be a mistake to project a new era of instability and terrorism based on this change. The death of a world leader is extremely costly. So any adaptation that the secret service can use to neutralize drone assassins that’s cheaper than letting more presidents die will be used. The effect of this shift of the Offense-Defense balance won’t be more deaths, it will be investment into powerful EMPs or counter-drones, or good old bullet proof glass.

The usual extrapolations of the offense-defense balance you hear are *upper bounds* of the costs that new offensive technologies can impose on defenders. If new technology enables $10,000 of drones to destroy a $10,000,000,000 dollar aircraft carrier, the actual cost imposed on defenders will not be losing all of their carriers. As long as there is any investment they can make that costs less than $10,000,000,000 dollars and neutralizes the drones, they will make it. Thus, shifts in the offense-defense balance are attenuated and somewhat self balancing: the more value that is imperiled by a new offensive technology, the more options that defenders can afford to neutralize it.

When the offense-defense balance changes due to some technology, prices and investment adjust to maintain a more stable equilibrium.