The European Commission's ruling that Apple should pay Ireland billions of dollars in back taxes was neither punitive nor unfair, one of the world's best-known economists told CNBC on Thursday.

Joseph Stiglitz said the European Commission (the European Union's executive arm) was right to conclude Ireland had granted Apple undue tax benefits. This is illegal under European rules and led the commission to order the Irish government to recover up to 13 billion euros ($14.5 billion) — plus interest — from Apple on Tuesday.