Perspectivism, Subjectivism, Practice

Practice is the modification of a World.  A Prospect is a concept of a modification of my World.  Now, the concept of Modification entails that of a Substratum.  But, as Kant shows, Subjectivism, e. g. Hume's 'bundle of perceptions', has no concept of a Substratum.  Hence, a significant advantage of Perspectivism over Subjectivism, as rival alternatives to Epistemological Realism, is that it has a Practical correlate.