 Another influential view on the rationality of emotions is that they help solve the commitment problem (Schelling 1960; Hirshleifer 1987; Frank 1988), which is the problem of convincing potential cooperative partners that one will fulfill promises and threats even when narrowly self-interested considerations would demand otherwise. For example, Frank (1988) has described the expression of sympathy as a mechanism to convince potential cooperators that one will behave honestly in future interactions even in the presence of temptation, and the expression of anger as a mechanism to convince potential cooperators that one will behave aggressively if messed with even when aggression is costly. These emotional signals are said to be credible because hard to fake, and they end up benefitting both partners, because they help secure the parties’ willingness to cooperate honestly in mutually beneficial projects (see also Ross &amp; Dumouchel 2004; O’Connor 2016).