 This result, known as Arrow’s impossibility theorem, prompted much work and many debates in social choice theory and welfare economics. William Riker (1920–1993), who inspired the Rochester school in political science, interpreted it as a mathematical proof of the impossibility of populist democracy (e.g., Riker 1982). Others, most prominently Amartya Sen (born 1933), who won the 1998 Nobel Memorial Prize, took it to show that ordinal preferences are insufficient for making satisfactory social choices and that social decisions require a richer informational basis. Commentators also questioned whether Arrow’s desiderata on an aggregation method are as innocuous as claimed or whether they should be relaxed.