  Counterfactual Thinking is a human cognitive ability studied in a wide
variety of domains. It captures the process of reasoning about a past event
that did not occur, namely what would have happened had this event occurred,
or, otherwise, to reason about an event that did occur but what would ensue had
it not. Given the wide cognitive empowerment of counterfactual reasoning in the
human individual, the question arises of how the presence of individuals with
this capability may improve cooperation in populations of self-regarding
individuals. Here we propose a mathematical model, grounded on Evolutionary
Game Theory, to examine the population dynamics emerging from the interplay
between counterfactual thinking and social learning (i.e., individuals that
learn from the actions and success of others) whenever the individuals in the
population face a collective dilemma. Our results suggest that counterfactual
reasoning fosters coordination in collective action problems occurring in large
populations, and has a limited impact on cooperation dilemmas in which
coordination is not required. Moreover, we show that a small prevalence of
individuals resorting to counterfactual thinking is enough to nudge an entire
population towards highly cooperative standards.
