[This is an Addendum to my paper on Descartes/Rand in the current issue of Journal of Ayn Rand Studies.]
Kant argued against Descartes’ view that the existence of one’s mind is more immediately and more certainly known than the existence of one’s body. Kant cast out Descartes’ view that the mind is a thinking substance. Because Kant rejected also Descartes’ ontological proof for the existence of God, Descartes’ first philosophy collapses. Metaphysical arguments to rational necessity of the existence of God or immortality of the soul are all cases of reason flapping its wings in a vacuum, by the lights of Kant. The Critique of Pure Reason (KrV) contains Kant’s case for a more limited scope for effective theoretical reason: stay within the bounds of possible sensory experience.
Kant accepted, as had Descartes and Aquinas before him, some notion that ‘I think’ entails ‘I am’. Then again, with Rand’s mature philosophy, acknowledgment that ‘Existence exists’ entails existence of one who acknowledges. For Kant, contra Descartes, ‘I think’ does not mean I think with a mental substance, radically distinct from body; and thinking of my body and of bodies outside me is as certain as the circumstance that I think and that I exist as a thinking thing. Kant had a role for ‘I think’ basic to his transcendental idealism, and such is not the role it had in the first philosophy of Descartes. Let me call Kant’s the “company-role” of ‘I think’.
“The ‘I think’ must be capable of accompanying all my presentations; for otherwise something would be presented to me that could not be thought at all—which is equivalent to saying that the presentation either would be impossible, or at least would be nothing to me.” (B131–32)
Kant’s ‘I think’ is utterly dependent on there being rational judgments it attends. ‘I think’ is not premier of knowing, contra Descartes. Neither it nor the ‘cogito sum’ containing it nor join of the ‘cogito sum’ to the premise of divine, absolute perfection amount to an adequate foundation of all human cognition.
We might object, however, to Kant’s reasoning in the quoted passage. In early development we each had been perceiving and investigating and coordinating without any ability to reflect and realize of those episodes ‘I am having’ or ‘I am doing’, let alone ‘I am thinking’. It might be countered for Kant, in our current context of cognitive developmental psychology, that to each such episode adults around the infant or toddler can attach ‘He is having’ or ‘She is doing’ and that grown older the former little one could say of filmed early episodes ‘I was seeing’, ‘I was searching’, and so forth. The objection remains, for those remarks would be merely as from outside and pronounced on the little person, not by that person as he or she perceived, investigated, and coordinated. That such episodes occur without first-person capability to reflect and realize ‘I am having’ or ‘I am doing’ means that, notwithstanding the important fact of the company-role of ‘I think’ for all mature, discursive human cognition, it is not a necessary condition for the possibility of all human cognition in the apriori way Kant argued at B131–32. Kant’s argument there ignores the existential fact that discursive thought has a genesis from and an alliance with prelinguistic thought in early development. When Kant does discuss the pertinent infant development, in his anthropology lectures, he foists the necessity argued in B131–32 off on all that development.
The company-role of ‘I think’ (as well as ‘I am having’ and ‘I am doing’) is a necessity for adult human cognition, though not for the ultimate reason and not with the type of ultimate necessity given it by Kant. And self-reflection is not a necessity for one’s earliest stage of cognition. The necessity of the company-role of ‘I think’ and its precursors ‘I am having’ and ‘I am doing’ is most basically biological, not transcendental. Without adult capability for some self-reflection, and its precursors in development, there will have been no capability for language, thence not yet human cognition in such a species.
Conceptual necessities are from the life of mind situated in larger life situated in the world. Conceptual necessities do not require Kant’s conceit of generative mind as ultimate origin of temporal and spatial organization in sensory experience and objective world nor Kant’s conceit of generative mind as base origin of its own fundamental concepts as forms with which the world as known shall be. Necessary conditions on the possibility of experience and cognition are in my view rightly seen as situated within biological necessities, not within Kant’s supposed, wider transcendental necessities. Organicism in human consciousness—with its unities, roles, interdependencies, and self-generations—is offspring of and sign of the biological nature of consciousness. Kant saw it rather the other way around. As with any other body, the body of a physical organism is in his view an object standing in spatial, temporal, and causal connections whose source of necessity is the transcendental synthetic unity of apperception. Organic unities of organisms, according to Kant, are to be seen as if they were designed by a cosmic intelligence, keeping in mind that those unities are projections of the unities of our own reason, which is to say organic unities of organisms are to be understood as if sourced (and as in fact divinely sourced) in organic unities of intelligence.
The ‘I’ of Kant’s company-role ‘I think’ is a unified conceptual maker of coherence from variety in the ‘I’s world of perception. As Béatrice Longuenesse observes: Because the causal relation is among the organizing principles constituting the coherence-making self that must be able to accompany any sensory experience it has, we have in Kant’s company-role ‘I think’ a post in Kant’s fence against Hume’s skepticism concerning necessary connection between distinct perceived events.
 Kant 1781(A) and 1787(B): A366–80, B274–79.
 A343–47 B401–6, A348–51, B407–8, B416–22. Rand, and I with her, replace substance of Aristotle or of Descartes with entity, and we would count the mind and the self as an entity, notwithstanding the special ways in which one knows one’s own mind and self.
 A592–603, B620–31.
 But see Heidegger 1953, 318–21/304–7.
 Kant, KrV B270–79.
 Also B137–39, B157–-58n, A341–43, B399–401, A347 B405, A354–55, A397- 402, B422–23n, B428–32, A848 B876; 1798, 7:127–28.
 Kitcher 2011, 57–62, 116–17, 193–97.
 Kant 1798, 7:128-29.
 Cf. Criticism of Kant, on possible origins of necessity in synthetic apriori judgments, by Gottlob Ernst Schulze 1792, 142–45.
 Mensch 2013, 99–109, 113–24, 130–45, 153–54.
 Kant, KrV A22–36 B37–53, B131–69, B232–34, A189–211 B235–56.
 A317–18 B374, B425, A686–704 B714–32.
 A67 B92, A107–8, A113–14, A119, A124–25, B129–39, A199–202 B244–47, A214–18 B261–65, A228–30 B281–82, A234–35 B286–87, A255-56 B311, A401–2; see also Kitcher 2011, 138–41, 144–50, 193–97.
 Longuenesse 2008, 15–16; see also Kitcher 2011, 152–57, 170–73; Allison 2008, 107–12, 204–5.
Allison, H. E. 2008. Custom and Reason in Hume – A Kantian Reading of the First Book of the Treatise. New York: Oxford University Press.
Heidegger, M. 1953 . Being and Time. 7th ed. J. Stambaugh and D. J. Schmidt, translators, 2010. Albany: State University of New York Press.
Kant, I. 1781, 1787. Critique of Pure Reason. W. S. Pluhar, translator. 1996. Indianapolis: Hackett Publishing.
——. 1798. Anthropology from a Pragmatic Point of View. In Immanuel Kant – Anthropology, History, and Education. G. Zöller and R. B. Louden, editors, 2007. G. Zöller, translator. Cambridge: Cambridge University Press.
Kitcher, P. 2011. Kant’s Thinker. New York. Oxford University Press.
Longuenesse, B. 2008. Kant’s “I Think” versus Descartes’ “I Am a Thing that Thinks.” In Kant and the Early Moderns. D. Garber and B. Longuenesse, editors. Princeton: Princeton University Press.
Mensch, J. 2013. Kant’s Organicism – Epigenesis and the Development of Critical Philosophy. Chicago: The University of Chicago Press.
Schulze, G. E. 1792. Aenesidemus. In Between Kant and Hegel – Texts in the Development of Post-Kantian Idealism. G. di Giovanni and H. S. Harris, translators, 2000. 2nd ed. Indianapolis: Hackett.