r/GAMETHEORY • u/Academic-Sound-7903 • 2d ago
Super-rationality extended to asymmetric games and dynamic games: sharing and welcoming feedback
Hello!
I am a researcher at ETH Zurich, Switzerland and I wanted to share some research I have been working on for more than 20 years (and which dates back to even more than 30 years through my mentor's work). I thought perhaps this might be interesting to the game theory community and it would be an opportunity to get feedback and make it a bit more visible.
It essentially comes down to a generalization of Douglas Hofstadter's super-rationality to non-symmetric games (normal form) and to dynamic games (extensive form) with or without perfect information, and its application to build a deterministic extension of quantum physics and for negotiations. The definitions and algorithms are peer-reviewed and published (except without perfect information, which is a preprint).
This is all based on the philosophical work by Jean-Pierre Dupuy, a Professor at Stanford University who was my mentor on this direction, and who wrote the two seeding papers in 1992 and in 2000. It took me years to digest his brilliant ideas. Dupuy suggested that classical game theory (Nash, Subgame Perfect Equilibrium) suffers from the backward induction paradox, and that this could be solved by completely changing the way we think about time and free choice.
Dupuy constructed a philosophical framework which he called Counterfactual Decision Theory ("Two temporalities, Two rationalities: a new look at Newcomb's paradox", 1992 [1]) that reconciles free choice and being correctly predicted: a compatibilistic form of free will. He also commonly refers to it in the philosophers' community as "projected time". Instead of considering the future as open and the past as fixed, he suggested to do the exact opposite: in an idealized, theoretical setup, the future is already known to all, and the past depends counterfactually on it. This makes it rational to pick one box in Newcomb's problem. He defined an ad-hoc prediction as a prediction that turns out to be correct, but that could have been incorrect if what is being predicted had happened differently ("could" in the formal sense of modal logic) and an essential prediction (we now call it Perfect Prediction) as a prediction that is correct, and that would also have been correct if what is being predicted had been different (counterfactual dependency in the sense of Lewis; not to be confused with logical implication). The fundamental difference with Causal Decision Theory is that counterfactual dependencies can be backtracking, and the difference with Evidential Decision Theory is that we are talking about probabilities of subjunctive conditionals, not about conditional probabilities (the two being different or not is known as Adam's thesis and is discussed in the philosophical literature).
Dupuy then suggested ("Philosophical foundations of a new concept of equilibrium in the social sciences: Projected equilibrium", 2000 [2]) that this can be the basis of a completely new kind of game theory. He started with the centipede game and suggested the concept of a Projected Equilibrium (we now call it Perfect Prediction Equilibrium), as a fixpoint problem, and went through a few examples. The fundamental idea is that Perfect Prediction leads to preemption: if a player were to select an outcome that a past player does not like, this would have led to a deviation in the past, which is a logical contradiction. This corresponds to a Kantian form of ethics with a categorical imperative that Dupuy formulated as "Never act in such a way that, if your action had been anticipated, it would not be within your power to carry it out." Dupuy conjectured that the equilibrium always exists, is always unique, and is always Pareto-optimal.
In 2004, I was able to formally define the definition and algorithm for all dynamic games in general position (it means there are no ties in payoffs) and with perfect information. I was also able to prove that his conjecture was correct for these games. With the help of another colleague of us, Stéphane Reiche, it took us ten years of submissions and rejections until we finally managed to get it published ("Perfect Prediction Equilibrium", 2014 [3]) after presenting in 2014 at an international Economic Philosophy conference. At that point, we thought there was a link with Douglas Hofstadter's superrationality, but this was more an analogy than a formal link.
In 2017, I managed to give definitions and algorithms for (possibly asymmetric) games in normal form in general position, and to show that (i) it does not always exist, (ii) when it does, it is unique and (iii) in the particular case of symmetric games, when it exists, it is always a Hofstadter equilibrium (superrationality, the max of the diagonal). Since I did not know for sure it was the "same" concept as the Perfect Prediction Equilibrium, I called it Perfectly Transparent Equilibrium. This time it took less time to publish ("Perfect Prediction in normal form: Superrational thinking extended to non-symmetric games", 2020 [4])
Then, to prove that these were the same, I suggested ("Games in Minkowski spacetime", 2020 [5]) to unify games in normal form and games in extensive form with perfect information to a broader category of so-called Spacetime Games. Such games can also be mapped as a subset of extensive form games with imperfect information, through a "linearization" of the dependency graph of decisions (interestingly, Lorentz transforms in relativity theory correspond to Thompson transforms in game theory!). Then I defined and gave algorithms for our equilibrium on dynamic games with imperfect information ("Perfect Prediction in Minkowski Spacetime: Perfectly Transparent Equilibrium for Dynamic Games with Imperfect Information", 2019 [6]), which finally showed that the Perfect Prediction Equilibrium and the Perfectly Transparent Equilibrium are the one and same. I now use the term "Perfect Prediction Equilibrium" for them all.
Now, about applications:
- I am actively looking into quantum physics, because the assumption of free choice we are changing is the exact same one that is needed in impossibility theorems (Bell inequalities, Kochen-Specker) and that prevents a deterministic extension. With my research assistant, Michael Baczyk, we published ("Nashian game theory is incompatible with quantum physics", 2023 [7]) a paper showing that Nash equilibria are incompatible with quantum physics and that a non-Nashian approach (such as the Perfect Prediction Equilibrium) is needed. (note that this is not the same as Quantum Game Theory; we convert general quantum experiments into (classical) spacetime games ("Spacetime Games Subsume Causal Contextuality Scenarios", 2026 [8]).
- This can also be used for negotiations: if two parties disagree, and the Nash equilibrium is not optimal, they can agree to sign a contract that commits them to the Perfect Prediction Equilibrium.
I started an online book to explain all of this in simpler terms than the formalism of the papers [9].
I hope I did not break any rules sharing this, not being very familiar with Reddit (otherwise I can delete). I hope this can generate some interest (there is so much more to explore in non-Nashian game theory) and I would kindly welcome any feedback from the community.
Thank you,
Ghislain Fourny
[1] https://www.sciencedirect.com/science/chapter/edited-volume/abs/pii/B9780080410500500236
[2] https://philpapers.org/rec/DUPPFO
[3] https://arxiv.org/abs/1409.6172
[4] https://www.sciencedirect.com/science/article/pii/S0022249620300183
[5] https://arxiv.org/abs/2004.11217
[6] https://arxiv.org/abs/1905.04196
[7] https://link.springer.com/article/10.1007/s40509-023-00309-0
[8] https://link.springer.com/article/10.1007/s10773-026-06295-4