Formally, a free-rider refers to someone who enjoys the benefits available to others without undertaking similar efforts (Fontaine, 2014). Naturally, this carries negative moral connotations. The free-rider is best illustrated in the famous Prisoner’s Dilemma. Presenting it in its basic formulation, Mayer (2014) writes:
The police have arrested two suspects in a crime, but lack evidence they would need to convict them. The police separate the prisoners for questioning. Each now faces a well-
Source: https://michigantoday.umich.edu/2019/09/26/the-prisoners-dilemma/
defined choice: to cooperate with his partner by remaining silent when questioned, or to defect by implicating his partner. If both cooperate by staying silent, the frustrated police can only imprison them for a short time on lesser charges. If, however, one defects (gives his partner up) while the other cooperates (stays mum), the defector gets a reward of serving no prison time, while his partner will get sent away for many years. If both defect (each implicates the other), they each get an intermediate number of years in prison (p. 15).
In the Prisoner’s Dilemma, each prisoner is faced with two possible actions: paying for the public good (to cooperate), or free-riding on other’s efforts (to defect). Let us illustrate this with dummy numbers:
| I cooperate | I defect | |
| Accomplice cooperates | 2 years each | 0 years for me, 10 years for him |
| Accomplice defects | 0 years for him, 10 years for me | 5 years each |
The temptation of free-riding enters when one realises that the best state of affairs is if one defects while their partner cooperates. Although collective action would bring about an arguably better state of affairs (4 collective years in prison instead of 10), we are better-served by letting our accomplice bear the cost of our crime while we go scot-free.
With respect to population growth, we can imagine a similar trade-off between an individual person and the global community. Where it is a tautology that we either reproduce or do not reproduce, we can assign reproduction to defection and non-reproduction to cooperation (since reproduction is harmful to the planet, as postulated, making it value-positive to the individual but value-negative to the planet and therefore the international community).
The impact on the environment that one incurs from his decision to bear a child is borne by the rest of the international community, but the pleasure of having a child is felt only by the person whose desires are satisfied via childbirth.