Reason is universal because no attempted challenge to its results can avoid appealing to reason in the end-by claiming, for example, that what was presented as an argument is really a rationalization. This can undermine our confidence in the original method or practice only by giving us reasons to believe something else, so that finally we have to think about the arguments to make up our minds.
Thomas NagelAltruism itself depends on a recognition of the reality of other persons, and on the equivalent capacity to regard oneself as merely one individual among many.
Thomas NagelTo look for a single general theory of how to decide the right thing to do is like looking for a single theory of how to decide what to believe.
Thomas Nagel