Theory vs Practice

Do we still hold on this argument? Are we still divided between a mental and physical world? Hume dismisses Descartes' 'cogito' by arguing that 'theory becomes an inquiry'. "Theory is an inquiry, which is to say, a practice: a practice of the seemingly fictive world that empiricism describes: a study of the conditions of legitimacy of practices in this empirical world that is in fact our own. The result is the great conversion of theory to practice" Deleuze Hume p.36 Deleuze adds in the same text that the origin of this conception can be found in Francis Bacon with his famous  'ipsa scientia potestas est' ("knowledge itself is power"). However it was after Hume that William James will popularize Pierce's conception of pragmatism where knowledge is produced in a pragmatic way where "the relation between knower and known 'works' in the world."