Comment on towards a unified analytical model for different types of Ribā

It is commendable that al-suwailem has directed islamic economics towards the field of theoretical inquiry about 'objectives of sharī'ah (the maqāsid) as embedded in the jurisprudential rulings on wealth and property. using tools of economic analysis,he attempts to confirm that the economic impact of ribā al- fadl is expected lead to concentration of wealth in the hands of rich thereby causing acute shortages of necessary goods and high costs of living for the underprivileged. however,the author relies on an incomplete reference to imam abu hamid al-ghazali in relation to the economic impact of ribā al-fadl . he builds a mathematical model that fails to address key questions about the difference between permissible barter and impermissible one at the level of microeconomic analysis. the co-existence of a ribā al-fadl market with the 'normal' market is adopted without proof. furthermore,the author adopts an unrealistic additive model for the production function,thus,ending up with an incorrect answer to the research question about the pattern of economic behavior associable with ribā al- fadl.