Kant’s Critique: Why Metaphysics Fails as Science
Kant on Metaphysics as Science
Immanuel Kant asks whether metaphysics can be a science. His answer is negative because the aim of metaphysics is to go beyond experience. Furthermore, it cannot provide synthetic judgments a priori grounded in experience, relegating its concepts primarily to the realm of morality.
Enlightenment Context and Hume’s Influence
Kant’s thesis is situated in the Age of Enlightenment, a movement opposing tradition, authority, and superstition, which also defended independence, progress, and science. Kant’s initial principles were rationalist, stating that all knowledge is based on reason. However, it was upon encountering the philosophy of David Hume that Kant awoke from his ‘dogmatic slumber’. He realized that empiricism, which maintains that all knowledge is based on experience, also plays a crucial role in epistemology.
Transcendental Idealism: Reason and Experience
Kant then synthesized both rationalism and empiricism, developing his own philosophical and epistemological doctrine: transcendental idealism. This is encapsulated in his famous statement: ‘All knowledge begins with experience, but not all knowledge arises out of experience.’ That is, both reason and experience are necessary to establish secure knowledge.
Kant’s Critical Philosophy Questions
Kant addresses fundamental questions in his major works:
- What can I know? – Explored in his Critique of Pure Reason (1781)
- What should I do? – Explored in his Critique of Practical Reason (1788)
- What may I hope? – Explored across his works, including concepts from the Critique of Judgment and writings on morality and religion.
The Structure of Knowledge
To address Kant’s objective (determining if metaphysics can be a science), we must understand his theory of knowledge presented in the Critique of Pure Reason.
Sensitivity and Understanding
He outlines two fundamental faculties involved in knowledge:
- In the Transcendental Aesthetic, he discusses sensitivity: the passive faculty that receives impressions (intuitions) through the senses, ordered by the a priori forms of space and time.
- In the Transcendental Analytic, he details the understanding: the active faculty responsible for developing concepts and applying them (the categories) to intuitions, thereby creating judgments and enabling thought about objects.
Types of Judgments: Analytic vs. Synthetic
For Kant, there are distinct types of judgments crucial to knowledge:
- Analytic judgments a priori: These do not add new knowledge, as the predicate is already contained within the subject (e.g., ‘All bodies are extended’). They are universal and necessary but merely clarify concepts, not expanding scientific knowledge.
- Synthetic judgments a posteriori: These add new knowledge based on experience, as the predicate is not contained within the subject (e.g., ‘This rose is red’). They are contingent and particular, dependent on specific experiences.
- Synthetic judgments a priori: Kant argued for this crucial third type. These judgments add new knowledge, yet are universal and necessary, not derived solely from experience (e.g., mathematical truths like ‘7 + 5 = 12’, or the principle that every event has a cause). The ideal for science, according to Kant, is to consist of such judgments, as they expand knowledge universally and necessarily.
Phenomena vs. Noumena: Limits of Knowledge
This framework explains why traditional metaphysics cannot be a science. Science deals with phenomena: appearances as structured by our cognitive faculties (through space, time, and the categories of understanding). Metaphysics, however, attempts to grasp noumena: things-in-themselves, their underlying reality independent of our perception and cognition.
Noumena are unknowable through theoretical reason because attempting to know them imposes the very conditions (space, time, categories) that define phenomena, preventing access to the thing ‘as it is in itself’.
Metaphysics: Failure as Science, Role in Morality
The traditional objects of metaphysics (God, the soul, the world as a totality) are considered noumenal. Therefore, theoretical knowledge of them is impossible. This leads to Kant’s distinction regarding metaphysics:
- Negative aspect: Metaphysics fails as a science within the realm of theoretical reason because it attempts to apply concepts beyond the limits of possible experience, leading to contradictions (antinomies), as detailed in the Transcendental Dialectic.
- Positive aspect: However, metaphysical ideas (like freedom, God, immortality) find a legitimate and necessary place within the realm of practical reason (morality). They function as necessary postulates for moral action, guiding conduct even though they cannot be proven by theoretical science.
Kant concluded that metaphysics cannot become a science because its objects and methods do not conform to the conditions required for scientific knowledge (synthetic judgments a priori grounded in possible experience). Instead, its proper domain lies in grounding morals and ethics.