His research interests are in political theory and comparative politics. He is currently completing a manuscript on freedom and toleration , as understood in ancient China and early modern Europe. Future projects include a re-examination of the "Asian values" debate and a comparative study of the concept of justice. In addition, he is engaged in research into the history of American politics thought, with a particular focus on issues concerning disagreement, diversity and the reception of non-Western thought within the U.S. His teaching interests at Duke Kunshan include ethics and leadership, global China studies, U.S. studies, institutions and governance, and political science.

Rathnam has a B.A. in philosophy (honors) from Davidson College, studied in the interuniversity program in Chinese language studies at Tsinghua University, and has an M.A. in East Asian studies and a Ph.D. in political science from the University of Toronto. He is a postdoctoral fellow at Emory University and in 2016-2017 was a visiting instructor in the Department of Political Science at Davidson College.