The term res cogitans — Descartes' designation for the thinking substance, the mind defined purely as thought — functions within the depth-psychology corpus less as a philosophical achievement than as a fateful error whose consequences ramify across centuries of Western intellectual life. Heidegger's Being and Time provides the most sustained critical engagement, reading res cogitans as an ontological failure: by grounding selfhood in cogitation rather than in Dasein's embodied, temporal being-in-the-world, Descartes foreclosed the question of the Being of this thinking entity and bequeathed to modernity an inadequate subject who confronts the 'world' as res extensa across an unbridgeable gulf. Simondon deepens this critique by arguing that the Cartesian move toward total homogeneity within the res cogitans — excluding body, memory, and imagination from the thinking substance — made impossible any conception of a continuous gradient between mind and somatic reality, effectively blocking the path toward individuation. Von Franz traces the term through Descartes' own dreams and alchemical proximities, identifying it with the soul as 'thing that thinks' while revealing the unconscious mythic pressures beneath the rationalist definition. Damasio, Craig, and McGilchrist approach the legacy from neuroscience and philosophy of mind: each, in distinct registers, mounts an empirical and phenomenological case against the disembodied cogito that res cogitans enshrines. The term thus marks, for the depth-psychology library, the inaugural wound of Cartesian dualism.
In the library
13 passages
This radical affirmation of homogeneity can only be effectuated by pushing back the limit between the res cogitans and the res extensa: the break is thus so abrupt between the aspects of thought most attached to the body and the body itself that the gulf between substances is insurmountable.
Simondon argues that Descartes' construction of a homogeneous res cogitans severs mind from body so absolutely that no continuous gradient between psyche and soma can be conceived, foreclosing genuine individuation.
Simondon, Gilbert, Individuation in Light of Notions of Form and Information, 2020thesis
working out the unexpressed ontological foundations of the 'cogito sum' … our Interpretation will not only prove that Descartes had to neglect the question of Being altogether; it will also show why he came to suppose that the absolute 'Being-certain' of the cogito exempted him from raising the question of the meaning of the Being which this entity possesses.
Heidegger identifies res cogitans as the site where Descartes suppressed the ontological question, treating certainty of the cogito as license to ignore the Being of the thinking entity altogether.
By taking his basic ontological orientation from traditional sources and not subjecting it to positive criticism, he has made it impossible to lay bare any primordial ontological problematic of Dasein; this has inevitably obstructed his view of the phenomenon of the world.
Heidegger argues that the dualism of res cogitans and res extensa, inherited uncritically, makes the phenomenon of world invisible and reduces ontology to a relation between two present-at-hand substances.
In Descartes we find the most extreme tendency towards such an ontology of the 'world', with, indeed, a counter-orientation towards the res cogitans which does not coincide with Dasein either ontically or ontologically.
Heidegger marks the decisive divergence between res cogitans and Dasein, insisting that the Cartesian subject is not equivalent to Dasein in any ontological register.
The soul is the 'res cogitans' … 'being, as I have demonstrated, nothing but a thing that thinks, it is impossible that we could ever think of anything without at the same time having the idea of our soul, as a thing capable of thinking everything we think.'
Von Franz, citing Barth's analysis of Descartes' letter to Mersenne, identifies the soul directly with res cogitans and notes the total identification of the soul's being with its thinking function.
von Franz, Marie-Louise, Dreams: A Study of the Dreams of Jung, Descartes, Socrates, and Other Historical Figures, 1998supporting
the res cogitans, consciousness, and the interconnectedness of Experience serve as the point of departure for methodical study. But since even the cogitationes … the inadequate ontological foundations have been overlooked.
Heidegger traces how modern anthropology absorbed res cogitans into its methodological starting point while perpetuating the unexamined and inadequate ontological foundations Descartes left unaddressed.
as res cogitans … he calls this 'I' a 'logical subject', that does not mean that the 'I' in general is a concept obtained merely by way of logic. The 'I' is rather the subject of logical behaviour, of binding together.
Heidegger examines the Kantian reformulation of res cogitans as the 'I think' that underlies all logical binding, contrasting this formal structure with the existential selfhood of Dasein.
I am therefore, speaking precisely, only a thinking thing, that is, a mind, or a soul, or an intellect, or a reason — words the meaning of which was previously unknown to me.
Descartes enunciates in primary text the foundational definition of res cogitans, identifying the self exclusively with thought and systematically separating it from bodily existence.
Descartes, René, Meditations on First Philosophy, 2008thesis
when I discover that I am a thinking substance and form a clear and distinct concept of this thinking substance, containing nothing that belongs to the concept of a bodily substance, this is quite sufficient for me to assert that, in so far as I know myself, I am nothing other than a thinking thing.
Descartes defends the methodological sufficiency of defining the self as pure thinking substance, arguing that the absence of bodily attributes in the clear and distinct concept grounds the real distinction.
Descartes, René, Meditations on First Philosophy, 2008supporting
Memory is a distance-taking, an acquisition of objectivity without alienation. It is an extension of the limits of the subjective system that takes on an internal duality without separation or rupture.
Simondon constructs a counter-model to the homogeneous res cogitans by showing that memory introduces internal duality and distance within the subject without the catastrophic rupture Descartes imposed between thinking substance and body.
Simondon, Gilbert, Individuation in Light of Notions of Form and Information, 2020supporting
each one of us grows up with the implicit understanding that body and mind are different … The adult version of this childhood perspective is called dualism.
Craig situates Cartesian dualism — the existential separation of cognitive mind from autonomous body — as a developmental acquisition rooted in early somatic experience, grounding the res cogitans/res extensa split in neurobiological and phenomenological soil.
Craig, A.D. (Bud), How Do You Feel? An Interoceptive Moment with Your Neurobiological Self, 2015supporting
Descartes's conception of the lumen naturale can be connected with these contemporary notions and is, in any case, based on a similar inner original experience … 'la raison' consists of multiple 'semina scientiae'.
Von Franz reads Descartes' rationalist epistemology — the inner light grounding the res cogitans — as a rationalisation of deeper alchemical and archetypal experiences of illumination, connecting it to the Jungian lumen naturale.
von Franz, Marie-Louise, Dreams: A Study of the Dreams of Jung, Descartes, Socrates, and Other Historical Figures, 1998aside
If the term 'Reality' is meant to stand for the Being of entities present-at-hand within-the-world (res) (and nothing else is understood thereby), then when it comes to analysing this mode of Being…
In distinguishing res as present-at-hand worldly entity from the res cogitans of Descartes, Heidegger clarifies that neither exhausts the ontological structure of Dasein or of reality as a whole.