For Kant, space and time are not properties of things in themselves but a priori forms of intuition, the necessary conditions that make experience possible. Centuries earlier, Nāgārjuna demonstrated that whatever arises through dependence lacks self-standing reality, revealing the emptiness of anything that claims to stand on its own. Their aims differ: Kant’s account is primarily epistemological, explaining how knowledge and experience are possible; Nāgārjuna’s is ontological, showing that nothing possesses independent being, not even the conditions or relations through which phenomena appear. Drawing on Nāgārjuna’s logic of dependence, the following discussion interrogates two assumptions in Kant’s framework: first, that there exists a noumenal, mind-independent reality; and second, that the mind’s a priori conditions possess transcendental priority over experience.
सर्वं तथ्यं [न वा तथ्यं] तथ्यं चातथ्यमेव च।
नैवातथ्यं नैव तथ्यमेतद्बुद्धानुशासनं॥
Beyond the four possibilities – that all is true, that nothing is true, that it is both true and not true, and that it is neither true nor not true – lies the middle way. This is not a compromise between extremes but the realization that “existence” and “non-existence” are both conceptually relational.
Limits of Perception
Time and Causality
“If the present and the future exist contingent upon the past,
Then the present and the future would be in the past.”
We assume the present and future depend on the past. Nāgārjuna exposes the paradox that if this were literally true, then the present and future would already exist in the past. The point here is ontological: if the past is truly gone, it cannot retain causal power because causation requires something presently existing to produce an effect.
A fire may leave ashes, but once the fire (cause) ceases, it cannot continue producing ashes (effect). The ashes could not have come after the fire completely ceased, because there exists no cause to bring them about. If the ash existed alongside the fire burning, the fire didn’t really precede the ash and hence did not produce it. They merely coexisted with a single relational process. It could be said that the fire gradually turned an object into ash, but we cannot find the precise moment of transformation: either the fire persists (simultaneity again) or it doesn’t (no cause). This reveals a contradiction in the assumed temporal order between cause and effect.
If time were static, we would experience no change. If it moved, it would have to move within another time, leading to an infinite regress. This argument is reductive rather than empirical. It is not a claim about temporal physics but about the conceptual structure that underlies our assumptions of succession. Nāgārjuna shows what happens when we treat time as an entity rather than a parameter. This does not deny empirical causation, where cause and effect coexist in time, but challenges the metaphysical presupposition that cause, effect, and the time that separates them are independent realities or that time is made of independent, real “parts” – past, present, and future. They exist only in mutual relation.
न स्वतो नापि परतो न द्वाभ्यां नाप्यहेतुतः।
उत्पन्ना जातु विद्यन्ते भावाः क्वचन के चन॥
No objects arise from themselves (a thing producing itself), for if the effect already exists in the cause, nothing new is produced. If it arises from something wholly other, the relation is unintelligible, and anything could produce anything. If it arises from both self and other, the contradictions double. If without a cause,anything could arise anywhere. A cause existing independently would produce eternally; if it required conditions, then it is not an independent cause. Thus, neither cause nor effect have autonomous existence. Every argument, when followed to its end, turns back upon itself and depends on the very ideas it tries to prove. Reasoning itself is relational.
Space and Motion
If motion exists in what has already moved, it will remain after movement has ended. If it exists in what has not yet moved, it will exist before movement begins. If it exists in what is moving now, the mover and the motion become identical. This concerns not physical motion but conceptual dependence: motion, like time, lacks ontological self-subsistence.
Likewise, no space is evident before spatial characteristics. If space existed before objects, it would be without spatial characteristics such as direction, distance, extension, and thus unintelligible. If it exists after, it depends on objects for its definition. Space, then, is not an independent expanse but a relational absence – lack of obstruction, empty of intrinsic nature.
Both Kant and Nāgārjuna reject space as an independent substance, though in very different ways. Kant recognizes it as a mental structure required for the possibility of perception; Nāgārjuna denies even the independent status of such structures. Conditions cannot be separated from what they condition. If space is just a concept that arises in relation to things, what happens to the concept when both “things” and “relations” are themselves empty?
Nāgārjuna’s analysis exposes the relational dependence of concepts like time, space, and causality, denying them any independent ground. Kant agrees that they are not properties of things in themselves but argues that they function as a priori forms through which the mind organizes experience. The following section examines the tension with this move.
Kant’s Framework
Kant divides reality into two aspects: appearances (phenomena) and things as they are in themselves (noumena), which lie beyond human cognition. We can never know the noumenal directly, but only how it appears through our a priori forms of intuition—space, time, and the categories of understanding like causality. By accepting this limit, Kant confines knowledge to experience and safeguards it from collapsing into pure subjectivity. He secures the possibility of objective knowledge by clarifying the conditions under which such knowledge is possible and limiting metaphysical speculation.
Questioning the Independence of the Noumenon (Ontological Dependence)
Kant posits things “in themselves” only because we already experience things “as they appear.” Without appearances, the very concept of a raw, mind-independent reality would never arise (here ‘dependence’ is conceptual, not causal). In that sense, the noumenal world, conceived as that which gives rise to appearances, actually depends on the phenomenal for its very possibility. If the notion of an unfiltered, independent reality arises only as something beyond appearance, then that “beyond” is not truly independent but conceptually parasitic upon the very phenomenon it is meant to transcend. It exists only in contrast and is therefore empty of self-existence.
Questioning the Priority of the A Priori (Epistemological Dependence)
In Kant’s framework, the mind is the active subject that organizes and knows, while the world is the passive object that is known. There is a one-way dependency here: the world depends on the mind for how it appears, but the mind depends on the world only for content, not for its structure. Its a priori forms like space and time are said to exist independent of experience and to make experience itself possible. This introduces an asymmetry between knower and known. Kant could speak of these built-in conditions only because appearances already exist to be organized. Without appearances, how could we ever know of the mind’s a priori forms? We cannot claim these conditions precede experience and make experience possible (precedence here is transcendental rather than temporal or causal). The mind and world arise together in mutual dependence. To see this is to see emptiness, not as nothingness, but as the absence of anything that stands alone, either epistemically or ontologically.
Emptiness
Things exist only through conditions: they are empty of self, yet full of relations. In that sense, even relations are not fundamental because they depend on what they relate to. Emptiness is not another concept; it too must be seen as empty, both epistemically (conceptually) and ontologically (in being). Emptiness here does not signify nihilism. It explains the relational structure of reality instead of denying it. It dissolves the dichotomy between appearance and reality that Kant preserves, revealing them as co-arising reflections of the same dependent process. Existence and non-existence are both extremes, and emptiness is their interdependence.
निर्वाणस्य च या कोटिः कोटिः संसरणस्य च।
न तयोरन्तरं किं चित्सुसूक्ष्ममपि विद्यते॥There is not even the subtlest difference between the extremities of bondage and liberation.
Further Reading :
Vallée Poussin, L. de la. (Ed.). (1913). Madhyamakavrttih. Mūlamadhyamakakārikās (Mādhyamikasūtras) de Nāgārjuna: Avec la Prasannapadā, commentaire de Candrakīrti. Paris: Société asiatique.
Nāgārjuna. Mūlamadhyamakakārikā of Nāgārjuna: The Philosophy of the Middle Way: Introduction, Sanskrit text, English translation and annotation (D. J. Kalupahana, Trans.).
Kant, I. (Trans. J. M. D. Meiklejohn). Critique of Pure Reason.
Plotinus. The Enneads (L. P. Gerson, Ed.; G. Boys-Stones, J. M. Dillon, L. P. Gerson, R. A. H. King, A. Smith, & J. Wilberding, Trans.). Cambridge University Press.
Radhakrishnan, S. (Ed. & Trans.). (1913). The Principal Upaniṣads: With introduction, text, translation, and notes. London: George Allen & Unwin Ltd.
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