The evolution of morality and the role of commitment

Area of Science:

• Evolutionary game theory
• Behavioral economics
• Moral psychology

Background:

• Existing research on human cooperation often focuses on why humans deviate from Nash equilibrium in simultaneous games (e.g., prisoners' dilemmas).
• This perspective may not fully capture the complexities of human pro-social behavior and moral sentiments.
• Sequential games, like the ultimatum and trust games, offer a more relevant framework for understanding evolved human behavior.

Purpose of the Study:

• To investigate why humans do not play the subgame perfect Nash equilibrium in sequential games.
• To propose that commitment mechanisms in sequential games better explain human morality and behavior.
• To differentiate the evolutionary drivers of human morality from those in other species.

Main Methods:

• Theoretical analysis of game theory models, specifically sequential games (ultimatum and trust games).
• Examination of 'rationally irrational' behavior as a product of commitment strategies.
• Comparative analysis of evolutionary pressures on human and animal moral sentiments.

Main Results:

• Deviations from subgame perfect Nash equilibrium in sequential games are explained by evolved commitment mechanisms.
• This 'rationally irrational' behavior aligns with observed human traits like honesty, responsibility, anger, and vengefulness.
• Commitment does not require repeated interactions or specific population structures, offering a universal evolutionary explanation.

Conclusions:

• The evolutionary function of morality is to facilitate commitment to otherwise irrational behaviors.
• This framework explains the evolution of human moral sentiments, distinguishing them from those of other animals.
• Robert Frank's work on commitment and emotions provides a foundational, yet underutilized, perspective on the evolution of morality.