I weakly agree with the claim that the offense/defense balance is not a useful way to project the implications of AI. However, I disagree strongly with how the post got there. Considering only cyber-security and per-capita death rate is not a sufficient basis for the claim that there is "little historical evidence for large changes in the O/D balance, even in response to technological revolutions."

There are good examples where technology greatly shifts the nature of war: castles favouring defense, before becoming negated by cannons. The machine gun and barbed wire are typically held as technologies that gave a significant defensive advantage in WWI, and were crucial in the development of trench warfare. Tanks similarly for offense. And so on. One would need to consider and reject these examples (which is certainly plausible, but needs to be actually engaged with).

I don't think the per capita mortality from war is a very useful measure of the O/D balance - it will be driven by many other confounding factors, and as you point out technologies alter the decision calculus of both sides of a conflict. Part of the problem with the O/D theory is a lack of well-defined measures (e.g.). From my impression of the literature, it also appears to fail in empirical predictions (e.g.). Cyber-security is a good example of an arena where O/D theory applies poorly (e.g.).  I think this section does well to support the claim that "shifting O/D balance doesn't dominantly affect the frequency and intensity of war", but it doesn't show that "technologies don't shift the O/D balance". 

So I disagree with the post by thinking that technologies can systematically favour aggressive vs. defensive actions and actors, but agree that this pattern doesn't necessarily result in strong implications about the rate or intensity of large-scale conflict. However, I think there can still be implications for non-state violence, especially when the technology enables an 'asymmetric weapon' - a cheap way to inflict very costly damages or demand costly defence. The prototypical example here being terrorist use of improvised explosives. This is an important channel for worries about future bioweapons.

The main thing is that the clean distinction between attackers and defenders in the theory of the offense-defense balance does not exist in practice. All attackers are also defenders and vice-versa.

I notice that this doesn't seem to apply to the scenario/conversation you started this post with. If a crazy person wants to destroy the world with an AI-created bioweapon, he's not also a defender.

Another scenario I worry about is AIs enabling value lock-in, and then value locked-in AIs/humans/groups would have an offensive advantage in manipulating other people's values (i.e., those who are not willing to value lock-in yet) while not having to be defenders.

Copying a comment from Substack:

If offence and defence both get faster, but all the relative speeds stay the same, I don’t see how that in itself favours offence (we get ICBMs, but the same rocketry + guidance etc tech means missile defence gets faster at the same rate). But ideas like this make sense, e.g. if there are any fixed lags in defence (like humans don’t get much faster at responding but need to be involved in defensive moves) then speed favours offence in that respect.

That is to say there could be a 'faster is different' effect, where in the AI case things might move too chaotically fast — faster than the human-friendly timescales of previous tech — to effectively defend. For instance, your model of cybersecurity might be a kind of cat-and-mouse game, where defenders are always on the back foot looking for exploits, but they patch them with a small (fixed) time lag. The lag might be insignificant historically, until the absolute lag begins to matter. Not sure I buy this though.

A related vague theme is that more powerful tech in some sense ‘turns up the volatility/variance’. And then maybe there’s some ‘risk of ruin’ asymmetry if you could dip below a point that’s irrecoverable, but can’t rise irrecoverably above a point. Going all in on such risky bets can still be good on expected value grounds, while also making it much more likely that you get wiped out, which is the thing at stake.

Also, embarassingly, I realise I don't have a very good sense of how exactly people operationalise the 'offence-defence balance'. One way could be something like 'cost to attacker of doing $1M of damage in equilibrium', or in terms of relative spending like Garfinkel and Dafoe do ("if investments into cybersecurity and into cyberattacks both double, should we expect successful attacks to become more or less feasible"). Or maybe something about the cost-per-attacker spending to hold on to some resource (or cost-per-defender spending to sieze it).

This is important because I don't currently know how to say that some technology is more or less defence-dominant than another, other than in a hand-wavery intuitive way. But in hand-wavey terms it sure seems like bioweapons are more offence-dominant than, say, fighter planes. Because it's already the case that you need to spend a lot of money to prevent most the damage someone could cause with not much money at all.

I see the AI stories — at least the ones I find most compelling — as being kinda openly idiosyncratic and unprecedented. The prior from previous new tech very much points against them, as you show. But the claim is just: yes, but we have stories about why things are different this time ¯\_(ツ)_/¯

Great post.

Forgive me if I'm thick, but isn't this equivalent to saying the elasticities of supply and demand for offense and defense rarely change over time? The price might go up or down, factor markets might change, but ratios remain stable?

This makes sense, but I worry it is not Hayekian enough. People are the ones who respond to price changes; nations are the ones who respond to price changes in the cost of defense, deterrence, and attack. In the long run, there is equilibrium. But in the short run, everyone is making adjustments all the time and the costs fluctuate wildly, as does who has the upper hand. 

The Athenians have the upper hand until Spartans figure out siege warfare, the 11th century nobles of Aragon and Barcelona are consolidated and made more subservient to the King-count Jaume II by his monopoly on trebuchets, the Mongols had logistics advances that gave them a 60 year moat.

The question isn't whether there is equilibrium, but how long until we get there, which equilibrium is it, and what mischief is caused in the meantime. Human action and choices determines the answer to these questions.