In philosophy, the ability to use reason to make decisions regarding possible actions and determine the optimal choice. Philosophy tends to privilege rationality over the instinct, the passional, and the willed, arguing that it is only by exercising reason that humans can be free. In some cases, it is argued that rationality only obtains in mathematics and the physical sciences and that all the other disciplines are too tainted by irrational elements. Some philosophers also hold that rationality is unique to humans, but this view has been seriously challenged in recent times. In contrast, the Frankfurt School is critical of rationality precisely because they see it as inhuman because it favours the smooth-running of systems (such as the economy) over the inconsistency of individual humans.