In this study we explore the endogenous determination of moral objections to free riding. We first derive the individually rational behavior for given preferences. The motivational structure is allowed to evolve evolutionarily based on the comparison of the relative reproductive success of all possible preference types. The tastes that emerge are not necessarily those assumed in models resorting to altruism or moral obligations. In general, an effective social conscience preventing free riding need not be evolutionarily stable. In the first model that we explore, moral objections to free riding and, in turn, voluntary contributions to the provision of public goods are not to be expected with one notable exception, namely unanimity games. In the second model that we explore, the evolutionarily stable probability that an individual develops social conscience is positive.