Classical economic theory assumes that economic agents are entirely self-interested and rational in their pursuit of material well-being, and that they are not affected by external factors. As a result, externalities are not considered in any way when constructing economic models. Nevertheless, some sociologists argue for a revision of modern economic theory to incorporate the ethical dimensions of economic agents' behaviour. Kirill Borissov, Professor of the Faculty of Economics at the European University in St Petersburg, spoke at the XXIV Yasin (April) International Academic Conference and shared his observations from creating his own economic model incorporating the factor of envy.