The depth-psychology corpus approaches ‘Rational Cognition’ not as a settled faculty but as a contested site where the boundaries between reason, affect, perception, and non-rational awareness are perpetually renegotiated. The tradition fractures along several fault lines. Plato and Aristotle, read through Lorenz, establish a foundational architecture: rational cognition is distinguished by its capacity to grasp logical relations, apply predicates, and discern means–end structures — capacities unavailable to the non-rational soul-parts, which operate through perception and phantasia alone. The Stoics, via Long and Sedley, further sharpen this by defining the wise man’s cognition as the disciplined withholding of assent from incognitive impressions. Yet the modern neuroscientific voices — Damasio, Barrett, Burnett, and LeDoux — mount a sustained challenge to the Cartesian inheritance, demonstrating that affect is structurally prior to deliberative cognition and that the ‘rational prefrontal cortex’ model is neurologically naive. McGilchrist synthesizes these tensions hemisphericaly, arguing that purely analytical, left-hemisphere rationality is not the apex of cognition but a limited mode requiring integration with embodied, right-hemisphere understanding. Sri Aurobindo reaches furthest, positing a supramental reason that supersedes the merely mental rational faculty altogether. The term thus marks, across the corpus, both an achievement and an overreach.