Causal categorisation arranges different fields within the ontogenetic level of behavioral science, psychology, in a system according to their causal and explanatory role, whether in terms of a distinction between or proximate and ultimate causes, mechanistic and contextual science, or final, efficient and material Aristotelian causal types. Although whether or not behavior analysis belongs to psychology is to some extent a semantic question, given that it does, it does not comprise the whole of psychology. It cannot replace neuroscience or perhaps even neurocognitve perspectives any more than evolutionary biology can replace genetics. Likewise, neuroscience or cognitive psychology cannot replace behavior analysis any more than genetics can replace evolutionary biology. The classical Mayrian distinction between proximate and ultimate causation in evolutionary biology confines psychology to the limited framework inherent in mechanistic causation (since proximal causal accounts are almost inevitably mechanistic in nature). Thus evolutionary psychology only cements a limited mechanistic psychology, in line with the dominating cognitivist paradigm. It is unfit to function as a unifying underlying theory of psychology and, more importantly, to charter interdisciplinary behavioral science. Evolutionary psychology is ripe with recent examples of unconvincing reduction of learning to mechanism. Another dimension that I identify, not forming an x-axis, as in level of selection, nor a y-axis, as in the causal categorisation between proximate and ultimate causation described above: Is level of reduction along a z-axis. Neurocognitivism is antireductionist relative to molecular and cellular neuroscience, which in turn is pro-reductionist relative to the former, forming a dimensional axis. A similar parallel dimensional axis arguably exists between atomic-molecular behavior analysis (pro-reductionist) and molar, or alternatively macro-molecular, behavior analysis (antireductionist). If all the pieces fall neatly into place the result should be a psychology that organises key fields along the lines of causal categorisation and levels of reduction, remedying both the causal categorical mistakes and classical Rylean categorical mistakes that continue to plague psychology, respectively. Or, in other words, psychology as the interdisciplinary behaviorist views it.