  Towards the realization of a sustainable, fair and inclusive society, we
proposed a novel decision-making model that incorporates social norms in a
rational choice model from the standpoints of deontology and utilitarianism. We
proposed a hypothesis that interprets choice of action as the X-point for
individual utility function that increases with actions and social norm
function that decreases with actions. This hypothesis is based on humans
psychologically balancing the value of utility and norms in selecting actions.
Using the hypothesis and approximation, we were able to isolate and infer
utility function and norm function from real-world measurement data of actions
on environmental conditions and elucidate the interaction between the both
functions that led from current status to target actions. As examples of
collective data that aggregate decision-making of individuals, we looked at the
changes in power usage before and after the Great East Japan Earthquake and the
correlation between national GDP and CO2 emission in different countries. The
first example showed that the perceived benefits of power (i.e., utility of
power usage) was stronger than the power usage restrictions imposed by norms
after the earthquake, contrary to our expectation. The second example showed
that a reduction of CO2 emission in each country was not related to utility
derived from GDP but to norms related to CO2 emission. Going forward, we will
apply this new X-point model to actual social practices involving normative
problems, and design the approaches for the diagnosis, prognosis and
intervention of social systems by IT systems.
