ABSTRACT
The public opinion on moral issues in the US has become more liberal for some issues, such as attitudes towards gay rights, while it has remained mostly stable for others, such as abortion. Only rarely does it become more conservative. Meanwhile, the population ratios of liberals and conservatives have remained largely unaltered over time. What is it then that drives moral norm change in the liberal direction in society? In this work we build on Moral Foundations Theory and investigate the assumptions and predictions made by a recent mathematical model on the dynamics of public opinion, in order to identify a micromechanism that could explain the outcome. In more detail, liberals tend to rely on a narrower set of moral foundations than do conservatives. According to the model, this fact should influence the speed and direction of moral opinion change among both liberals and conservatives.