HOUSE_OVERSIGHT_015502.jpg

290
M. Hoffman et al.

com’s most inefficient charities. Yet its mission of fulfilling wishes by children
with terminal illnesses is identical to that of the more efficient Make-A-Wish
Foundation. Worse yet, scams masquerading as charities persist. One man oper-
ating as The US Navy Veteran’s Association collected over 100 million dollars—
over 7 years!—before anyone bothered to investigate the charity.
3. In every culture and age, injunctions against murder have existed. If there is one
thing much of humanity seems to agree on, it’s that ending the life of another
without just cause which is among the worst of moral violations. Yet cultures
don’t consider the loss of useful life years in their definition, even though it is
relevant to the measure of harm done by the murder. Why is our morality so
much more sensitive to whether a life was lost than to how much life was lost?

There are numerous other examples of how our moral intuitions appear to be rife
with logical inconsistencies. In this chapter, we use game theory to provide insight
on a range of moral puzzles similar to the puzzles described above.

What Is Game Theory and Why Is It Relevant?

In this section, we review the definition of a game, and of a Nash equilibrium, then
discuss how evolution and learning processes would yield moral intuitions consis-
tent with Nash equilibria.

Game theory is a tool for the analysis of social interactions. In a game, the payoff
to each player depends on their actions, as well as the actions of others. Consider
the Prisoner’s Dilemma (Chammah & Rapoport, 1965; see Fig. 1), a model that
captures the paradox of cooperation. Each of two players chooses whether to coop-
erate or to defect. Cooperating reduces a player’s payoff by c > 0 while increasing
the other’s payoffs by b > c . Players could be vampire bats with the option of
sharing blood, or firms with the option of letting each other use their databases, or
premed students deciding whether to take the time to help one another to study. The
payoffs, b and c, may represent likelihood of surviving and leaving offspring, prof-
its, or chance of getting into a good medical school.

Solutions to such games are analyzed using the concept of a Nash equilibrium¹—
a specification of each player’s action such that no player can increase his payoff by
deviating unilaterally. In the Prisoner’s Dilemma, the only Nash equilibrium is for
neither player to cooperate, since regardless of what the other player does, cooperation
reduces one’s own payoff.

¹ Note that we focus on the concept of Nash equilibrium in this chapter and not evolutionary stable
strategy (ESS), a refinement of Nash that might be more familiar to an evolutionary audience. ESS
are the Nash equilibria that are most relevant in evolutionary contexts. However, ESS is not well
defined in many of our games, so we will focus on the insights garnered from Nash and directly
discuss evolutionary dynamics when appropriate.

HOUSE_OVERSIGHT_015502