 Even though the double inductive method is now mainly of historical interest, Morgan's canon lives on.  Questions about quite what the canon means and how to justify it are active topics of historical and philosophical investigation (e.g., Burghardt 1985; Sober 1998, 2005, 2012; Radick 2000; Thomas 2001 (Other Internet Resources), Fitzpatrick 2008). The questions include what Lloyd Morgan means by ‘higher’ and ‘lower’, to what extent the principle can or should be justified by evolutionary considerations, and whether the canon collapses to a principle of parsimony, a version of Ockham's razor, or some general principles of empirical justification. Despite current uncertainty about what it really means, Morgan's canon, interpreted (or, perhaps, misinterpreted; Thomas 2001, Other Internet Resources) as a strong parsimony principle, served a central rhetorical role for behavioristic psychologists, who sought to eliminate any hint of Cartesian dualism from comparative psychology.