Another criticism is based on Dworkin's assertion that positivists' claims amount to conventionalism. H. L. A. Hart, as a soft positivist, denies such claim as he had pointed out that citizens cannot always discover the law as plain matter of fact. It is however unclear as to whether Joseph Raz, an avowed hard positivist, can be classified as conventionalist as Raz has claimed that law is composed "exclusively" of social facts which could be complex, and thus difficult to be discovered.