The term ‘non-rational’ occupies a pivotal and contested position across the depth-psychology corpus, spanning ancient philosophy, Stoic ethics, phenomenology of religion, and contemporary neuroscience. In the Platonic-Aristotelian tradition, the non-rational designates specific parts or aspects of the soul—appetite, spirit, phantasia—that operate independently of, or in qualified deference to, reason. Lorenz’s reconstruction of both Plato and Aristotle shows that non-rational motivation is not mere chaos: it involves genuine cognitive resources, notably phantasia, which provides the representational substrate for desire and locomotion. The Stoics, as documented by Inwood and Long and Sedley, deny the non-rational its own standing in rational animals—emotion belongs exclusively to the rational soul, and animals’ impulses are structurally analogous to, yet categorically distinct from, human passions. Rudolf Otto’s phenomenology of religion inaugurates a different and equally decisive treatment: the non-rational names the irreducible experiential core of the holy—the numinous—which resists conceptual capture yet demands schematization by rational theology. For Otto, a religion’s vitality depends on holding rational and non-rational elements in creative tension. McGilchrist’s neurological perspective reframes the non-rational as what the left hemisphere systematically misrepresents or excludes, while the right hemisphere preserves its living reality. Across these traditions, the non-rational is never simply the irrational; it is the ground that reason must reckon with, accommodate, or be corrected by.
THE RATIONAL AND THE NON-RATIONAL But, when this is granted, we have to be on our guard against an error which would lead to a wrong and one-sided
Otto establishes the conceptual pairing of rational and non-rational as the central analytical problem of the idea of the holy, cautioning against a one-sided rationalist reduction.
, The Idea of the Holy: An Inquiry into the Non-Rational Factor in the Idea of the Divine and Its Relation to the Rational, 1917thesis
By the continual living activity of its non-rational elements a religion is guarded from passing into ‘rationalism’. By being steeped in and saturated with rational elements it is guarded from sinking into fanaticism or mere mysticality
Otto argues that the health of religion requires a dialectical balance between non-rational vitality and rational structure, with the degree of their harmony serving as a criterion of religious rank.
, The Idea of the Holy: An Inquiry into the Non-Rational Factor in the Idea of the Divine and Its Relation to the Rational, 1917thesis
Aristotle’s theory of human psychology not only leaves room for, but in fact requires, a conception of non-rational cognition that is applicable to ordinarily developed, adult human beings.
Lorenz argues that Aristotle’s psychology mandates a robust conception of non-rational cognition as a permanent, parallel feature of adult human action-production, not a mere deficiency or back-up system.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006thesis
appetite and spirit are non-rational forms of motivation, and a similarly clear and robust sense in which the cognition involved in these forms of motivation can, and to some extent must, be non-rational.
Lorenz, arguing on Aristotle’s behalf, maintains that appetite and spirit constitute genuinely non-rational motivational and cognitive forms even within a broadly rational human soul.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006thesis
the key concept Aristotle employs in explaining non-rational motivation—phantasia, that is—has significant Platonic antecedents.
Lorenz identifies phantasia as the central explanatory concept for non-rational motivation in Aristotle, tracing its philosophical genealogy back through Plato.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006thesis
non-rational action is analogous to rational action. One consequence of the non-rational character of animal action is that they are not capable of ‘passions’, pathê, which are perversions of rational behaviour.
Inwood expounds the Stoic doctrine that non-rational animals possess only analogues of passion and assent, establishing a categorical boundary between non-rational impulse and genuinely rational emotion.
, Ethics and Human Action in Early Stoicism, 1985thesis
something else in her struggles and exerts itself against reason, impelling her to act in a way that reason opposes. The non-rational part of her soul
Lorenz traces Aristotle’s account of self-controlled action to demonstrate that the non-rational part of the soul actively contests reason, requiring the soul’s rational part to prevail over genuinely competing motivational forces.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
what he is committed to, so far as non-rational motivation is concerned, is not that phantasia is required for the formation of every desire, but that it is required for the formation of desires that impel animals to engage in locomotion.
Lorenz refines the scope of Aristotle’s commitment regarding phantasia and non-rational motivation, restricting its necessity to locomotion-directed desires rather than all desire.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
non-rational soul-parts calls for clarification of what cognitive resources are available to them.
Lorenz notes that attributing genuine cognitive resources to the non-rational soul-parts is a theoretical necessity that Plato himself recognized, especially in the Timaeus and Philebus.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
Plato’s psychological theory acknowledges that everyone forms objectionable non-rational desires at least every once in a while.
Lorenz documents Plato’s recognition that non-rational desires are universal in human psychology, making their management by reason a general ethical problem rather than a pathological exception.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
some impressions are rational, and others non-rational. Those of rational animals are rational, while those of non-rational animals are non-rational. Rational impressions are thought processes; irrational ones are nameless.
Long and Sedley present the Stoic classification of impressions by rationality, establishing that non-rational impressions belong categorically to non-rational animals and lack the propositional structure of rational thought.
, The Hellenistic Philosophers, 1987supporting
Aristotle plainly insists that phantasia is different from thought, and that none of the cognitive achievements of the brute animals counts as an act of thought.
Lorenz establishes that Aristotle rigorously distinguishes phantasia from reason, thereby grounding the non-rational status of animal cognition in its exclusion from practical thought.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
There is no suggestion, here or elsewhere, that the appetitive part needs any support or assistance from reason so as to originate an action.
Lorenz uses the Timaeus to demonstrate that Plato’s appetitive part is fully capable of autonomous action-origination, confirming its non-rational independence from reason.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
misdescribing the non-rational part that poetry appeals to.
Lorenz notes an interpretive dispute about which non-rational part of the soul poetry targets in Plato’s Republic, indicating the theoretical complexity attending the identification of non-rational soul-parts.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
our normal practice of attributing emotions to animals and infants is at least in many cases indispensable, although it may not carry all the implications of other attributions.
Sorabji challenges the Stoic refusal to attribute genuine emotions to non-rational animals, arguing that ordinary attributive practice is defensible even if it does not carry the full weight of Chrysippean judgment-theory.
, Emotion and Peace of Mind: From Stoic Agitation to Christian Temptation, 2000supporting
Considered alone and per se, it necessarily and naturally looks more like the opposite of religion than religion itself.
Otto describes how the earliest non-rational religious moment—daemonic dread—appears, when isolated, more like a pathology than a religious phenomenon, illustrating the interpretive dangers of studying the non-rational in abstraction.
it is a central part of the theory that reason can work out and accomplish its own objectives by relying on its own distinctive resources, which enable it to grasp the true natures of things
Lorenz clarifies that Plato’s reason is not merely instrumental to non-rational goals but possesses its own irreducible ends, implicitly demarcating the rational from the non-rational by reference to the capacity for grasping truth.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006aside