Relational Thinking Styles is traced to Peirce’s phenomenology, his logic and concept of abduction. A process similar to Peirce’s descriptions of this phenomenological sort of proto-abduction is demonstrated and observed by means of the Davis Non-Verbal Assessment of inferencing styles. Noticing, or failing to notice, similarities and differences among things resides at the core of reasoning; all similarities and differences are discerned based upon the qualities of things, for there is no possibility of discernment without qualities to discern among. A mind cannot think about what it does not notice or has not previously noticed. Individuals become aware of similarities between things and ideas order and organize qualities, or properties, which distinguish one thing from another. Peirce’s practice of phenomenology as a whole comprises the qualitative core of reasoning. Since these three universal categories underlie the structure of Peirce’s philosophy as a whole, they underlie his logic as well. In particular, these phenomenological categories are essential for understanding his concept of abduction and, therefore, Peirce’s Logic.