Social dilemmas are situations in which private interests are at odds with collective interests. Such situations arise because people frequently attach more weight to their short-term selfish interests than to the longterm interests of the group, organization, or society to which they belong. Many of the most challenging issues people face, from the interpersonal to the intergroup, are at their core social dilemmas.

Consider these examples. As individuals, we are each better off when we make use of public services such as schools, hospitals, and recreational grounds without contributing to their maintenance. However, if we each acted according to our narrow self-interest, then these resources would not be provided, and everyone would be worse off. Similarly, in the long run, everyone would benefit from a cleaner ...