True acausal trade can only really work in toy problems, since the number of possible utility functions for agents across possible worlds almost certainly grows much faster with agent complexity than the agents’ abilities to reason about all those possible worlds. Whether the multiverse is deterministic or not isn’t really relevant.
Even in the toy problem case, I think of it as more similar to the concept of execution of a will than to a concept of trade. We carry out the allocation of resources of an agent that would have valued those allocations, despite them no longer existing in our causal universe.
There are some elements relevant to acausal trade in this real-world phenomenon. The decedent can’t know or meaningfully affect what the executors actually do, except via a decision structure that applies to both but is external to both (the law in this example, some decision theory in more general acausal trade). The executors now can’t affect what the decedent did in the past, or change the decedent’s actual utility in any way. The will mainly serves the role of a partial utility function which in this example is communicated, but in pure acausal trade many such functions must be inferred.
I think the fact that the multiverse is deterministic does play a role, since if an agent’s utility function covers the entire multiverse and the agent cares about the other branches, its decision theory would suffer paralysis since any action have the same expected utility—the total amount of utility available for the agent within the multiverse, which is predetermined. Utility functions seem to only make sense when constrained to one branch and the agent treats its branch as the sole universe, only in this scenario will different actions have different expected utilities.
You are not entitled to the assumption that the other parts of the multiverse remain constant and uncorrelated to what you do. The multiverse could be superdeterministic. Failing to take into account your causes means you have a worldview in which there are two underdetermined events in the multiverse, the big bang and what you are about to do. Both versions can not be heeding local causation and everything is connected.
It makes life a whole lot more practical if you do assume it.
True acausal trade can only really work in toy problems, since the number of possible utility functions for agents across possible worlds almost certainly grows much faster with agent complexity than the agents’ abilities to reason about all those possible worlds. Whether the multiverse is deterministic or not isn’t really relevant.
Even in the toy problem case, I think of it as more similar to the concept of execution of a will than to a concept of trade. We carry out the allocation of resources of an agent that would have valued those allocations, despite them no longer existing in our causal universe.
There are some elements relevant to acausal trade in this real-world phenomenon. The decedent can’t know or meaningfully affect what the executors actually do, except via a decision structure that applies to both but is external to both (the law in this example, some decision theory in more general acausal trade). The executors now can’t affect what the decedent did in the past, or change the decedent’s actual utility in any way. The will mainly serves the role of a partial utility function which in this example is communicated, but in pure acausal trade many such functions must be inferred.
I think the fact that the multiverse is deterministic does play a role, since if an agent’s utility function covers the entire multiverse and the agent cares about the other branches, its decision theory would suffer paralysis since any action have the same expected utility—the total amount of utility available for the agent within the multiverse, which is predetermined. Utility functions seem to only make sense when constrained to one branch and the agent treats its branch as the sole universe, only in this scenario will different actions have different expected utilities.
You are not entitled to the assumption that the other parts of the multiverse remain constant and uncorrelated to what you do. The multiverse could be superdeterministic. Failing to take into account your causes means you have a worldview in which there are two underdetermined events in the multiverse, the big bang and what you are about to do. Both versions can not be heeding local causation and everything is connected.
It makes life a whole lot more practical if you do assume it.