I and Self-Interest

The reduction of Soul to Mind enables Descartes to take the 'I' of his procedure as given as a Substance.  Similarly, the Human Mode and the Monad are each a self-evidently substantive I to Spinoza and Leibniz, respectively.  But, Locke points out the lack of evidence in their premise of the identity of 'I' from moment to moment.  So, eventually, Hume insists that the I is no more than a bundle of perceptions.  However, that insight does not seem to hamper his positing of Self-Interest as a fundamental behavioral principle.  In contrast, Kant does seem to recognize the discrepancy, but it is unclear if his proposed resolution is adequate.  For, on the one hand, his varieties of a Refutation of Idealism, express his acceptance of Hume's dismantling of the Rationalist I.  But, on the other, his proposed upgrade of the behavioral I--based on the concept of a continuous effort to act Rationally--still does not adequately explain the presupposed identity over Time of that I.  Furthermore, it leaves unaddressed the perhaps most easily overlooked element of his principle of Practical Reason--who the 'You' of 'Act only on that maxim that you can at the same time will to be a universal law' might be.  So, a fundamental pervasive inadequacy of the preceding era continues with Kant--the groundlessness of the generally accepted principle of Self-Interest, in any of its varieties.  It is that groundlessness that enables Smith to equally groundlessly transform Selfishness from the traditional Self-Preservation, to Profit-Seeking, the consequences of which have been evident in the centuries since.