The mainstream economics we know now is an even more perverted version of Smith’s work. In an earlier book ‘The Theory of Moral Sentiments’, he argued that societal and moral sentiments are important to exercise self-control. He also believes that government should be necessary in supporting the moral framework such as providing education to the poor. This part of his work is generally ignored in mainstream economics framework while the idea of self-interest shines eminently.
The recent literature on Islamic economics hardly makes use of mathematics even for expositional purposes. Mathematics is a language. It keeps argument and logic straight. Just like growth models could talk of seemingly non-mathematical concepts like public infrastructure, social infrastructure and governance, one can incorporate Islamic principles to show how they could be more welfare enhancing. For instance, the need is to show the impact and effects of Islamic principles on allocation of resources, income distribution, externalities and so on using mathematics.
Islamic Economics Project 