Epistemic status: pretty unsure about this, but I'm unlikely to be thinking much about multiverse-wide cooperation for a while, and the thought seemed plausibly worth making public.
Oesterheld (pg. 51) gives five preconditions for agents who can benefit from multiverse-wide superrational cooperation (MSR), and has suggested that one intervention worth exploring is making people more consequentialist (pg. 78). Insofar as I understand his argument, I take him to be saying: 'in worlds where acausal decision theorists are more consequentialist, we have an increased ability to enter into multiverse-wide acausal trades which are beneficial from the perspective of both parties. We should thus increase the number of consequentialists, so that more trades of this kind are made.'
I think another way of creating benefits is to make causal decision theorists more Kantian. That is, I think a Kantian CDT agent would have reason to engage MSR, as they meet all five preconditions outlined, and I think would engage in all the positive-sum acausal trades outlined in Oesterheld's paper. So making CDT agents Kantian also increases the number of multiverse-wide trades made which are beneficial from the perspective of both parties.
Let me be clear on what I'm saying: I think many people's attractors for Kant will be with certain object-level views they take him to endorse, like the imperssibility of lying. That is not what I mean to refer to. I am instead referring to someone who endorses the following claim:
Kantian Claim: The proper object of rational evaluation is not located at the level of acts, but rather at the level of maxims, which are of the form: 'I will do A in contexts C in order to achieve E'. The test for such maxims are those that can be willed without contradiction to be a universal law. This is sometimes called the first categorical imperative.
The canonical example is 'promising'. Suppose I am deliberating over whether to break a promise; I cannot (it is usually assumed) coherently will promise-breaking to be a universalisable maxim. This is because one would be unable to act on such a maxim in a world universalised so as to achieve its on purpose. If such a maxim were universal, there could be no institution of promise-making.
Oesterheld offers examples, like counterfactual mugging, where he says CDT agents would not precommit to cooperate with agents in other parts of the multiverse.
Omega decides to play a game of heads or tails with you. You are told that if the coin comes up tails, Omega will ask you to give it $100. If it comes up heads, Omega will predict whether you would have given $100 if the coin had come up tails. If Omega predicts that you would have given it the money, it gives you $10,000; otherwise, you receive nothing. Omega then flips the coin. It comes up tails, and you are asked to pay $100.
Do you pay? Oesterheld claims yes, as long as the outcome of the coin-flip is unknown. He also claims that CDT agents would answer no, unless Omega predicted based on a future version of that CDT agent. I claim that the Kantian CDT agent should answer yes, as long as they too are uncertain about the outcome of the coin-flip. The maxim: 'in contexts where you have some choice of action , where acts and deliver, with certainty, outcomes and respectively, and then make choice ' can be universalised without contradiction, and delivers strictly better causal consequences than any other maxim. The Kantian CDT agent should thus pay.
I think the point generalises: Kantians care about furthering their ends, and so any situation whereby consequentialist EDT agents find deals to have high expected utility, so too will a Kantian CDT agent. This is because any scenario in which an act has positive evidential (but not causal) expected utility for consequentialist agents will be one in which agents who perform do better, overall, at furthering their ends in situations of type . Kantians will, then, precommit to performing in , as Kantians evaluate the rationality of maxims rather than simple acts. If we believe there are positive gains from multiverse-wide cooperation, then Kantian outreach to CDT agents is a way of helping us achieve gains from multiverse-wide acausal trade.