Barriers to Entailment

A barrier to entailment exists if you can''t get conclusions of a certain kind from premises of another. One of the most famous barriers in philosophy is Hume''s Law, which says that you can''t get normative conclusions from descriptive premises, or in slogan form: you can''t get an ought from an is. This barrier is highly controversial, and many famous counterexamples were proposed in the last ce...