A Critique of Diminishing Musharakah

Abstract The metaphysics of the time-value concept differs fundamentally between conventional and Islamic finance. While conventional finance operates on the axiom that "there is a time-value of money," Islamic finance inverts this principle, holding that "everything except money may have a time-value." This distinction arises because Islamic finance assigns economic value to time only when it is connected to exchange of real assets, provision of genuine services, or engaged in productive activity. It therefore explicitly denies time-value to "money as money" granting it only to "money as capital" embedded in real economic activity. This is the core of the prohibition of Riba. Consequently, to test or evaluate any Islamic financial instrument or contract, the essential criterion is whether money within it is treated merely as money or substantively as capital. This paper analyzes Diminishing Musharakah (DM), hailed as the flagship product of modern Islamic finance, against this basic criterion. Rather than representing an evolution of Islamic principles, we argue that mainstream implementation of DM constitutes a tertium quid: a problematic third category that neither qualifies as authentic partnership nor legitimate exchange. Through sophisticated financial engineering, DM replicates the risk-return profile of conventional loan while employing Islamic legal forms as mere scaffolding. Our analysis demonstrates how DM betrays the foundational Islamic distinction by treating money predominantly as "money" rather than as "capital" throughout the contract, thereby serving more as accommodation to conventional finance than as an authentic alternative. The paper systematically examines whether DM's financial flows derive from genuine economic gains or merely contractual stipulations divorced from economic reality.