From 'is' to 'ought'

摘要

The Enlightenment philosopher David Hume pointed out long ago that no combination of statements about what "is" the case could ever allow one to deduce what "ought" to be. After all, in deductive arguments, the truth of the conclusion is already contained in the premises. But when scientists deal in morality, deducing an "ought" from an "is" is often precisely what they attempt to do.