A lot of mistakes come from assuming rationality means “thinks the same way I do” rather than “reasons from premises I might not share.”
Less than 1/1000 economists predicted the financial collapse, because they reasoned from assumptions like “the market is self-correcting” or “housing prices never go down.” (Sometimes both at the same time, which is rarely rational.)
Back in 2008 I wrote an article saying the next war w/Russia would be over Sevastopol/Crimea. I was told by Eurocrats that was impossible, because it would be irrational: the energy trade was too big to risk, Putin needed it. Rational. Putin didn’t see it that way, either then or now: Crimea and Sevastopol were Russian regions, strategically and emotionally important. When Ukraine seemed serious about cancelling the Sevastopol naval base lease, he acted.
Right now I hear a lot of people saying things like “never give into nuclear blackmail because then Russia will keep using it” or “Putin is rational, he would never use nuclear weapons.”
Now I don’t think he will, but I don’t think it’s impossible, even if one considers Putin rational. All he has to have is a scenario where he believes that he will get more than he will lose.
So, imagine that at some point Russia wants to end the war with Ukraine but doesn’t or can’t conquer enough to force a peace. Or imagine that there is a fake peace (no peace treaty) and Ukraine keeps dropping artillery shells into territory Russia says is theirs now.
Putin might, rationally, decide that the way to force a peace is to indicate that if war continues, he’ll go nuclear and if people don’t believe him, drop a tac-nuke or two to prove he’s not bluffing. (Remember, blackmailers who kidnap people often DO kill the victim. They aren’t bluffing.)
He thinks that the West is not really willing to risk a nuclear war and that if he is willing to risk one they will back down, especially if what he wants isn’t really that big. That’s a rational belief. It might be wrong, but it’s not irrational.
Or perhaps Putin gets into a scenario where he’s losing the war badly, and believes that if he does either he loses power and maybe his life; or that the Western maximalists will succeed in breaking up Russia. If the only way to stop that is to drop a nuke or two, why not? The US dropped nukes on Japan for less reason, although it’s true that no one else had nukes back then.
But what does the West do? If they tit-for-tat, and drop a tac-nuke or two, that means general war: Ukraine doesn’t have nukes, remember, so a NATO country has to attack and that will lead to nuclear war pretty fast if Putin thinks he can’t win a general war. (This is also true of a conventional war against Russia by NATO. Once he’s used tac-nukes, what makes you think he’ll stop when faced by a much more powerful enemy?)
The idea that Putin won’t use nukes is based on the idea that the risk of armageddon is always greater than whatever he expects to achieve. But what if he figures he can only die once or that Russia will cease to exist if he doesn’t use them, or that using them is the only way to stop a long drawn out fake peace? Also, remember that to some people dying by nukes and dying any other way is still just dying.
Now I have to say that think Russia is very unlikely to use nukes , even tac-nukes, but I also feel uneasy ruling it entirely because it is quite easy to come up with scenarios where Russian leadership decides the gain is worth the risks. This is even true if Russia feels backed into a corner, or if they are in an Afghanistan or Spanish Ulcer situation (Napoleon constantly losing troops in Spain). An ongoing bleeding which can’t otherwise be stopped might be worth risking nuclear war. If you’re going to lose anyway without it, why not risk it?
This, by the way, is why fighting a nuclear superpower over what they consider a core interest (notice “they”, not what you think, but what they think) is so risky and why the USSR and the US danced around each other like ponderous elephants. “If we really fight, we both lose.”
If Russia wants to win in Ukraine more than we (and given our support for Ukraine, it is “we”) do, they may well use nukes. Pretending it’s impossible is stupid and very very dangerous.