In this blog post, we will explore why people help others and uphold social norms without personal benefit, focusing on the reciprocity hypothesis and human social instincts.
In the movie ‘Titanic,’ the male lead Jack Dawson sacrifices himself to save the woman he loves as their ship sinks. Most viewers witnessing this scene would be moved by the protagonist’s sacrifice. Yet, questioning the protagonist’s sacrifice can help us understand cooperative behavior in human society.
While the above example is extreme, it represents a form of ‘altruistic behavior’. Altruistic behavior refers to actions that benefit others but result in a loss for the actor themselves. To easily understand altruistic behavior, consider a situation where high school student A borrows gym clothes from friend B. From B’s perspective, the clothes might get sweaty and dirty, making this an altruistic act requiring sacrifice. Therefore, not lending the clothes is the more beneficial decision for B. Even if A has frequently lent B their gym clothes before, or often treated B to delicious food, the fact that it is still more beneficial for B not to lend the clothes now remains unchanged. Yet, B lends the gym clothes to A, and we take this decision for granted. Why is that?
Let’s explain this question using the Reciprocity Hypothesis, one of the models explaining human altruistic behavior. According to this hypothesis, human altruistic behavior follows the principle: “I am only willing to help someone if they have helped me before.” In other words, if you lent me gym clothes before, I will lend you gym clothes now, or I will help you now so you will help me later. The principle of “an eye for an eye” forms the basis of reciprocity. Viewed from another angle, lending the gym clothes now (cooperative act) can be seen as an act of cooperation motivated by the fear that you might not lend them later (retaliatory act).
Let’s examine cooperative acts involving a third party. If B asks A to borrow gym clothes, C, who doesn’t know A, has no chance of receiving help later even if they lend the clothes. Yet even in this case, C is highly likely to lend the gym clothes to A. This stems from indirect reciprocity. According to indirect reciprocity, if my betrayal becomes known not only to my opponent but also to people around them, it could lead to greater retaliation, thus discouraging betrayal. In other words, if C refuses to lend the gym clothes to A, the cooperative relationship between B and C could be damaged, so C cooperates with A. This indirect reciprocity is more effective in smaller groups where bonds between members are stronger.
For the principle of reciprocity to hold, it presupposes that interactions between actors will continue. If there is no longer a need to cooperate in the future—that is, if there is no risk of retaliation—then betraying yields greater benefit. Therefore, the repeated reciprocity hypothesis can only explain situations where interactions between actors continue or are highly likely to repeat, leaving the end of the interaction uncertain.
Here, we see the limitation of the repeated reciprocity hypothesis. Altruistic acts like tipping occur even in situations unlikely to repeat, such as dining at a restaurant in a travel destination. In such cases, not tipping carries no risk of future retaliation. While not tipping would be personally advantageous, people choose to tip despite the loss. Thus, altruistic behavior in the absence of retaliation cannot be explained by the reciprocity hypothesis. This is because the reciprocity hypothesis assumes ‘retributive’ humans who seek to maximize their own interests. The retributive human has the limitation of being unable to consider social norms or agreements.
Furthermore, in systems like human society where many interact, the retaliation of the repetition-reciprocity hypothesis is difficult to enforce properly. When betrayal occurs in transactions involving many participants, it is hard to identify the betrayer. In this case, since retaliation against the betrayer is impossible, betrayal becomes the best choice for members to maximize their own benefit.
Even if the betrayer is identified, if punishing them incurs costs, it becomes difficult for anyone to step forward and retaliate.
As examined earlier, the Repetition-Reciprocity Hypothesis—which posits that cooperation arises because betrayal negatively impacts long-term transactions when interactions between actors are repeated—requires two premises. First, the probability of repeated transactions between the two actors must be high. Second, actors must behave according to the principle of reciprocity, “an eye for an eye.” The repetition-reciprocity hypothesis is appealing because it can explain altruistic behavior in countless recurring situations in our daily lives. However, it has limitations: not all situations where altruistic behavior occurs are repeated, and the principle of reciprocity does not apply well in transactions involving many parties. The reason the repetition-reciprocity hypothesis inevitably has limitations is that humans are not purely retaliatory. Humans strive to act in accordance with social norms and conventions even in non-repetitive situations. To address the limitations of the repetition-reciprocity hypothesis, consideration of this aspect of human behavior is necessary.
