Knecht, for “able to be reached” substitute “labeled fizzbin”. I have told you when to label something fizzbin. The labeling algorithm does not make use of the concept of “possibility”, but it does make use of surgery on causal graphs (the same sort of surgery that is involved in computing counterfactuals); you must have a modular model of the world in which you can ask, “If by fiat node A had value a1, what value would its descendant node B (probably) take on?” This well-specified computation does not have to be interpreted as indicating physical possibility, and in fact, in all but one cases, the world thus computed will not be realized.
The algorithm does use a list of actions, but you do not have to interpret these actions as physically possible (all except one will end up not being taken). I have simply told you flatly to label them “fizzbin” as part of this useful optimization algorithm.
Knecht, for “able to be reached” substitute “labeled fizzbin”. I have told you when to label something fizzbin. The labeling algorithm does not make use of the concept of “possibility”, but it does make use of surgery on causal graphs (the same sort of surgery that is involved in computing counterfactuals); you must have a modular model of the world in which you can ask, “If by fiat node A had value a1, what value would its descendant node B (probably) take on?” This well-specified computation does not have to be interpreted as indicating physical possibility, and in fact, in all but one cases, the world thus computed will not be realized.
The algorithm does use a list of actions, but you do not have to interpret these actions as physically possible (all except one will end up not being taken). I have simply told you flatly to label them “fizzbin” as part of this useful optimization algorithm.