How can humans make precommitments?

How can you precommit to something where the commitment is carried out only after you know your commitment strategy has failed?

It would seem to make it impossible to commit to blackmail when the action of blackmail has negative utility. How can you possibly convince your rational future self to carry out a commitment they know will not work?

You could attempt to adopt a strategy of always following your commitments. From your current perspective this is useful but once you have learned your strategy has failed, what’s to prevent you from just disregarding the strategy?

If a commitment strategy will fail you don’t want to make the commitment but if you will not follow the commitment even when the strategy fails then you never made the commitment in the first place.

For example, in nuclear war why would you ever retaliate? Once you know your strategy of nuclear deterrence has failed, shooting back will only cause more civilian casualties.

I’m not saying commitments aren’t useful, I’m just not sure how you can make them. How do you prevent your future self from reasoning their way out of them?

I apologize if reading this makes it harder for any of you to make precommitments. I’m hoping someone has a better solution than simply tricking your future self.