Qusthan A. H. Firdaus teaches logic, ethics and political philosophy at the Faculty of Ushuluddin, UIN Syarif Hidayatullah, Jakarta. He has been developing the notion of ‘adat logic’ whose foundation is various ‘adat laws’ across the Southeast Asian archipelago. He accomplished a postgraduate degree in ethics at the University of Melbourne and an undergraduate degree in philosophy at the Gadjah Mada University, Yogyakarta.