Primary Narcissism and the Existence of Others

Marcuse's re-connection of an Ego to 'the' universe in Primary Narcissism does not suffice as a bridge to other Egos, only to their outward appearances.  The seemingly unsuperable challenge to such an ambition is that the immediate evidence that would prove the existence of one Subject to another is impossible, for which no hypothesis is an adequate substitute.  However, this standard approach to the problem misconceives it as one of Cognition.  Rather, as Kant and Levinas, among very few, recognize, it is a Moral problem--either one treats another as a subject-in-itself, or one does not, with respect to which conceiving it as an Epistemological problem is an evasion, witting or otherwise.  Likewise, Marcuse's attempt to construct from mere Primary Narcissism a Socialist society, which entails mutual recognition of the Subjectivity of others, is inherently futile.