Humans are intuitively cooperative(1). Humans are also capable of deliberation, which includes social comparison(2), self-reflection(3) and mental simulation of the future(4). Does deliberation undermine or sustain cooperation? Some studies suggest that deliberation is positively associated with cooperation(5), whereas other work indicates that deliberation (vis-a-vis intuition) impairs cooperation in social dilemmas(6,7). Do some aspects of reasoning qualify whether deliberation sustains cooperation or impairs it? Here, we propose that wise reasoning(8-10)-that is, taking a bigger-picture perspective of the situation, including sensitivity to temporal and social interdependence between events-helps to integrate self-protective and cooperative goals, thereby sustaining cooperation when deliberating. Study 1 demonstrated that individual differences in wise reasoning about personal conflicts moderated the impact of naturalistic and experimentally manipulated deliberation time on cooperation. Studies 2 and 3 manipulated an observer perspective, the key aspect of wise reasoning, which eliminated the negative effect of deliberation time on cooperation. Under these circumstances, participants reported being guided by interdependent goals when making their decisions; thus, in these conditions, deliberation sustained cooperation. Combining scholarship on wisdom and behavioural economics, the present insights qualify the relationship between deliberation and prosociality, and highlight conditions under which wisdom promotes prosociality.