Much of the literature concerned about Psychology’s conceptual disarray and disunity remains unaware of, or disinclined to consider, the essential role that metaphysics has in addressing these matters. Properly understood, metaphysics involves what it is to be and to become, that is, what must be involved for anything to occur. Accordingly, metaphysics belongs to the phenomena that psychologists study. If we take the constituents of reality to be complex networks of situations that change over time through the dynamic interplay of parties, it is possible to derive a set of metaphysical categories that constitute the ontological conditions necessary for anything to occur, including bio-psycho-social processes. These conditions of existence are the placeholders for knowledge generally and they entail excluders for conceptual errors, that is, there is a logic to the metaphysical categories which any theory, model, or method in Psychology should observe. This logic bears heavily on relationality, and it is evident that beneath Psychology’s surface of “progress-being-made,” many conceptualize a range of topics in ways that are at odds with the logic of relations. These topics include types of dependence and the concept of constitution, representational cognition, reification, meaning, the “measurement imperative,” qualitative research, and causation. In short, if Psychology were to take metaphysics seriously, it would begin not with method (as has historically been the case) but with the conditions of existence. They provide the ontological justification for hermeneutic inquiry and qualitative research in Psychology; they are the fundamental counterpoint to conceptual disarray and disciplinary fragmentation—they unify.