Chapter II has provided an ontology of mind-body. Phenomenology is the explication of being-for-us (vide Chapter I C 1c). Though the ontology's claim to veracity lies in mirroring the essential structure of reality, it is not complete by itself; nor is its necessity fully evident. In order to secure our ontology, we will examine the possibility of alternatives. Indeed part of this ontology's significance is the exclusion of alternatives. By excluding both dualism and monism it establishes itself as an ontology of a special kind; it describes an identity in difference. But an alternative which it does not exclude defines its incompleteness, and will take us to the question of the dialectic. Thus, in order to develop our account we turn to others.