Immanuel Kant: Transcendental Idealism and Critical Philosophy

The Philosophical Foundations of Immanuel Kant

Kant's reflection takes as its starting point the rationalism of Leibniz and Wolff, the empiricism of Hume, the ideas of the French Enlightenment, and advances in physics and mathematics.

The Three Periods of Kantian Thought

We can divide the work of Kant into three distinct periods:

1. The Pre-Critical Period

During this time, he published numerous works, first on physical issues and then on philosophy:

• History of Nature and Theory of Heaven (1755)
• Observations on the Feeling of the Beautiful and Sublime (1764)
• Dissertation on the Form and Principles of the Sensible and Intelligible World (1770)

2. The Critical Period (1770–1790)

This period opens with a long silence of nearly 11 years, during which he elaborated the Critique of Pure Reason (1781). This work establishes the conditions for all scientific knowledge.

The Critique of Pure Reason aims to limit the scope and possibilities of theoretical or speculative reason, regardless of its empirical content. The development of this work poses limits on metaphysics and its objects (God, soul, freedom, and the world as a whole) regarding knowledge, as these ideas cannot be apprehended by the senses.

Through an analysis of reason itself, Kant sets the limits that nature cannot surpass. His conception of ethics is reflected in:

• Groundwork of the Metaphysics of Morals (1785)
• Critique of Practical Reason (1788)

In these works, reason is considered from a practical rather than a theoretical use. This is where Kant establishes the categorical imperative as the supreme principle of morality. In the Critique of Judgement (1790), he produced a synthesis of the two uses of reason, with unification taking place at the aesthetic trial.

3. The Post-Critical Period (1790–1804)

Key works from this final stage include:

• Religion Within the Limits of Reason Alone (1793)
• Perpetual Peace (1795)
• Metaphysics of Morals (1797)

These works focus on morality, law, and various writings on the philosophy of history. Kant's transcendental idealism is a turning point in the history of philosophy; it is inevitable that any further research in the field of thought must assume his legacy.