8 There are necessary truths that apply to all possible worlds. Natural alternative: recognize that it is hard enough to figure out what is true in this world, and there is no reliable way of establishing what is true in all possible worlds, so abandon the concept of necessity.

All possible, given what? That's what I find lacking. All possible just becomes all thinkable, which then becomes an argument over semantic commitments.

I believe EY is thinking of Pearl's do(x) action on a causal model, so that the "given what" is well defined as the causal model and associated state. Given everything else in the model except for the event changed by the intervention do(x) and it's causal effects.