Jean-Baptiste André
@jbaptistandre.bsky.social
Evolutionary biologist studying human behavior and societies through adaptationist reasoning. CNRS researcher @ Ecole Normale Supérieure-PSL & Institut Jean Nicod.
6/ Read the article @royalsocietypublishing.org
👉 doi.org/10.1098/rspb...
Evolutionary parsimony: an equilibrium refinement that sharply constrains the space of outcomes in games with multiple equilibria | Proceedings of the Royal Society B: Biological Sciences
Evolutionary game theory loses much of its predictive power in games with multiple
equilibria. For such games, this article introduces a simple and general refinement
principle, grounded in evolutiona...
doi.org
September 24, 2025 at 8:54 AM
6/ Read the article @royalsocietypublishing.org
👉 doi.org/10.1098/rspb...
5/ Main consequence: in plausible evolutionary equilibria, reciprocal cooperation is guided by real cues of mutual benefit, never by bizarre rules tied to arbitrary cues unrelated to payoffs.
September 24, 2025 at 8:54 AM
5/ Main consequence: in plausible evolutionary equilibria, reciprocal cooperation is guided by real cues of mutual benefit, never by bizarre rules tied to arbitrary cues unrelated to payoffs.
4/ What this article shows:
In reality, the bizarre strategies of the folk theorem simply have no chance of ever emerging in the first place. So there is no need for mechanisms to choose between them—the problem is essentially an artefact of misapplied game theory.
In reality, the bizarre strategies of the folk theorem simply have no chance of ever emerging in the first place. So there is no need for mechanisms to choose between them—the problem is essentially an artefact of misapplied game theory.
September 24, 2025 at 8:54 AM
4/ What this article shows:
In reality, the bizarre strategies of the folk theorem simply have no chance of ever emerging in the first place. So there is no need for mechanisms to choose between them—the problem is essentially an artefact of misapplied game theory.
In reality, the bizarre strategies of the folk theorem simply have no chance of ever emerging in the first place. So there is no need for mechanisms to choose between them—the problem is essentially an artefact of misapplied game theory.
3/ The most common solution in the literature: group selection.
Since equilibria are too many, you (supposedly) need group selection to pick the most cooperative ones.
Since equilibria are too many, you (supposedly) need group selection to pick the most cooperative ones.
September 24, 2025 at 8:54 AM
3/ The most common solution in the literature: group selection.
Since equilibria are too many, you (supposedly) need group selection to pick the most cooperative ones.
Since equilibria are too many, you (supposedly) need group selection to pick the most cooperative ones.
2/ Why is this a problem?
Because it prevents game theory from making precise predictions about social behavior.
Because it prevents game theory from making precise predictions about social behavior.
September 24, 2025 at 8:54 AM
2/ Why is this a problem?
Because it prevents game theory from making precise predictions about social behavior.
Because it prevents game theory from making precise predictions about social behavior.
1/ The old problem: the folk theorem and the extravagant diversity of equilibria in repeated games.
Game theory allows a proliferation of bizarre, counterintuitive patterns of behavior to qualify as equilibria.
Game theory allows a proliferation of bizarre, counterintuitive patterns of behavior to qualify as equilibria.
September 24, 2025 at 8:54 AM
1/ The old problem: the folk theorem and the extravagant diversity of equilibria in repeated games.
Game theory allows a proliferation of bizarre, counterintuitive patterns of behavior to qualify as equilibria.
Game theory allows a proliferation of bizarre, counterintuitive patterns of behavior to qualify as equilibria.