The rational faculty occupies a contested but central position across the depth-psychology corpus, functioning simultaneously as the crown of psychic architecture and as one constituent among others in a more complex economy of mind. In the Stoic lineage — Epictetus, Marcus Aurelius, and their modern commentators — it appears as the self-examining, self-legislating power that alone can assess all other faculties, judge appearances, and constitute human dignity. For the Stoics as reported by Long and Sedley, passions are not sub-rational disturbances but modifications of the rational faculty itself, a thesis that grounds the entire therapeutic programme of philosophy as medicine for the soul. Nussbaum presses this point with precision: if passions are wholly constituted by rational judgements, then a rational art of correcting judgements is, in principle, sufficient for their cure. Plato distributes the rational faculty hierarchically among soul-parts and assigns it sovereignty over appetite and spirit. Aristotle complicates the picture by insisting that something in the soul shares in reason without being fully rational, thereby making the rational faculty a regulative rather than a simply constitutive principle. Jung repositions the term entirely: thinking and feeling are both rational functions, while sensation and intuition are irrational — a typological redefinition that disengages 'rational' from 'superior' and treats rationality as one psychological attitude among four. The field thus moves between a tradition that assigns the rational faculty supreme authority and a depth-psychological counter-tradition that relativises it within a wider ecology of psychic functions.
The rational faculty; for this is the only faculty that we have received which examines itself, what it is, and what power it has, and examines all other faculties
Epictetus identifies the rational faculty as uniquely self-reflexive and as the sovereign judge of every other psychic and perceptual power.
, Discourses, 108thesis
if passions are not sub-rational stirrings coming from our animal nature, but modifications of the rational faculty, then, to be moderated and eventually cured they must be approached by a therapeutic technique that uses the arts of reason
Nussbaum articulates the Stoic therapeutic thesis: because passions are modifications of the rational faculty, rational art alone is sufficient to cure them.
, The Therapy of Desire: Theory and Practice in Hellenistic Ethics, 1994thesis
Jung held that feeling and thinking are rational functions, and that sensation and intuition are irrational functions. He did not sustain the faculty psychologists' opposition between reason and passion.
Beebe explicates Jung's typological redefinition whereby the rational faculty is split between thinking and feeling, dissolving the traditional reason-versus-passion binary.
, Energies and Patterns in Psychological Type: The Reservoir of Consciousness, 2017thesis
nothing is superior to the world ; therefore the world has the faculty of reason. A similar argument can be used to prove that the world is wise, and happy, and eternal
Cicero transmits the Stoic cosmological argument that the rational faculty, as the highest power, must be possessed by the world itself, making reason a cosmic rather than merely human attribute.
, De Natura Deorum (On the Nature of the Gods), -45thesis
Reason, therefore, is the capacity to be reasonable, a definite attitude that enables us to think, feel, and act in accordance with objective values.
Jung, via Schopenhauer and Jerusalem, reconceives the rational faculty not as a transcendent power but as a psychic attitude oriented toward objective values.
, Psychological Types, 1921thesis
something else in her struggles and exerts itself against reason, impelling her to act in a way that reason opposes … it nonetheless shares in reason in a way
Lorenz reconstructs Aristotle's position that appetitive desire is neither wholly rational nor wholly alien to reason, complicating the sovereignty of the rational faculty over conduct.
, The Brute Within: Appetitive Desire in Plato and Aristotle, 2006supporting
God had need of irrational animals to make use of appearances, but of us to understand the use of appearances
Epictetus distinguishes mere use of appearances (shared with animals) from rational understanding of them, locating the rational faculty as the specifically human contribution.
, Discourses, 108supporting
anything that is rational, and operatively good. For all these things, if once though but for a while, they begin to please, they presently prevail, and pervert a man's mind
Marcus Aurelius argues that pleasures and honours corrupt by contesting with the rational faculty's sovereign orientation toward the genuinely good.
, Meditations, 180supporting
nothing more valuable than the divinity implanted within you, and this is master of its appetites, examines all impressions, and has detached itself from the senses
Hadot's edition of the Meditations presents the rational faculty as the divine interior principle that masters appetite and examines impressions, constituting the highest human good.
, The Inner Citadel: The Meditations of Marcus Aurelius, 1998supporting
nothing more valuable than the divinity implanted within you, and this is master of its appetites, examines all impressions, and has detached itself from the senses
Parallel to the 1998 edition, this passage confirms the Stoic identification of the rational faculty with the indwelling divine governing principle.
, The Inner Citadel: The Meditations of Marcus Aurelius, 1992supporting
Chrysippus' value judgements are not after all necessary for emotions, since mere appearance can take the place of judgement
Sorabji challenges the strict Chrysippan identification of passion with rational judgement by showing that sub-doxastic appearances can generate emotional states independently of the rational faculty's assent.
, Emotion and Peace of Mind: From Stoic Agitation to Christian Temptation, 2000supporting
will is rational, free and natural desire, and in the case of man, endowed with reason as he is, the natural appetite is ruled rather than rules
John of Damascus locates the rational faculty as the regulative principle over natural appetite, making rational will the defining mark of human freedom.
, Saint John of Damascus Collection, 2016supporting
impulse is sometimes generated as a result of the judgement of the rational part, but often as a result of the movement of the passional part
Posidonius's critique of Chrysippus, as reported by Long and Sedley, argues that impulse has two independent sources, questioning the rational faculty's exclusive causal role in emotion.
, The Hellenistic Philosophers, 1987supporting
Our normal waking consciousness, rational consciousness as we call it, is but one special type of consciousness, whilst all about it, parted from it by the filmiest of screens, there lie potential forms of consciousness entirely different
William James, cited by Siegel, relativises the rational faculty by situating it as merely one species of consciousness surrounded by other modes it cannot easily access.
, The Developing Mind: How Relationships and the Brain Interact to Shape Who We Are, 2020supporting
thought, weighing the truth or falseness of the notion, determines what is true … That, however, which is judged and determined to be true, is spoken of as mind
John of Damascus maps the rational faculty onto the scholastic hierarchy of presentation, notion, thought, and mind, locating it as the discriminating power that establishes truth.
, An Exact Exposition of the Orthodox Faith, 2021supporting
the mind is the form of forms and sense the form of sensible things … no one can learn or understand anything in the absence of sense
Aristotle's account of the intellect as the form of forms places the rational faculty in dependency on sensory content, limiting its purely autonomous operation.
, On the Soul (De Anima), -350aside
Is not the noble that which subjects the beast to the man, or rather to the God in man; the ignoble, that which allows the beast to rule
Plato figures the rational faculty as the divine in man, whose nobility consists in subjugating the bestial elements of the composite soul.
, Republic, -380aside