Kant’s Ethics and Epistemology: A Comparative Analysis with Hume
Kant’s Ethics
After completing the “Critique of Pure Reason,” which answered the question “What can I know?”, Kant focused on the question: “What should I do?” He devoted two books to this: “Critique of Practical Reason” and “Groundwork of the Metaphysics of Morals.” Kant’s ethics centers on reason as the justification for moral law and duty. Morality, for Kant, is about how we act (whether good or bad). It’s a matter of understanding the will, not as it is, but as it should be, expressed through constraints or mandates.
To understand moral knowledge, Kant distinguishes two types of imperatives:
- Hypothetical Imperatives: These command actions as a means to achieve an end.
- Categorical Imperative: This commands actions as an absolute end, valid for all rational beings.
Kant argues that moral laws must be a priori. Hypothetical imperatives are problematic because their validity is conditional and based on experience. Moral norms, however, are not judgments of experience but are a priori. Therefore, Kant focuses on the categorical imperative.
A moral action, according to Kant, is one performed out of duty, not because of its consequences. The categorical imperative dictates: “Act only according to that maxim whereby you can at the same time will that it should become a universal law.” Goodness, for Kant, is not the foundation of moral law; rather, the moral law determines what is good. The source of morality is the law, and goodness lies in the will. We act out of respect for the law, though our desires can make this challenging. The relationship between virtue and happiness is complex; virtue does not guarantee happiness, nor does happiness guarantee virtue. Kant posits three principles of practical reason:
- The immortality of the soul, guaranteeing indefinite progress in virtue and happiness.
- The existence of God, ensuring virtue and happiness ultimately coincide.
- Freedom, allowing actions to be determined by reason, not external factors.
Comparison Between Kant and Hume
Knowledge
Let’s compare Immanuel Kant and the consistent empiricist David Hume, both from the 18th century. In their theories of knowledge, Hume, based on empiricism, argues that all knowledge comes from impressions gained through experience, with memory forming ideas. These are matters of fact, providing contingent and probable, but not universal, knowledge. Hume also acknowledges knowledge related to the relations between ideas created by our minds. He denies the possibility of metaphysics as knowledge and science, as what is obtained through the senses cannot be universalized, even denying the ideas of cause and substance.
Kant, on the other hand, argues that knowledge must fulfill two conditions: formal and empirical. He defends the law imposing the first possibilities, while the second condition concerns experience. Scientific judgments are synthetic a priori (universal and necessary). Thus, science is possible due to sensibility and understanding. However, he also denies metaphysics as knowledge because it doesn’t satisfy the material condition, despite admitting that humans cannot live without metaphysics. Kant also includes the principle of causality as one of the twelve categories of understanding. In conclusion, Hume would say that not being able to know the essence of things makes science absurd, but Kant would argue that we can build knowledge from what we perceive (phenomena), even without knowing the essence of objects in reality.
Ethics
These authors held opposing ethical doctrines. Hume defended moral emotivism, where knowledge guides us in choosing between good and evil, but our feelings and emotions ultimately determine our choices. Kant considered emotivism absurd, basing his ethics on the rational dimension of humans. According to Kant, we must be guided by duty and reason, following categorical imperatives. For Kant, being swayed by passions leads to egoism. His formal ethics is disinterested.
In political theory, Hume, consistent with his ethics, advocated a utilitarian system that maximizes happiness (“the greatest happiness for the greatest number”). Kant, however, defended republicanism and opposed despotism. While Kant might accept utilitarianism if it led to a republican constitution, he rejected direct democracy or despotism because they don’t secure freedom, equality, and legal dependence on a common law. Hume’s political theory allows for various possibilities, while Kant’s specific system is based on a republican constitution aimed at perpetual peace, strengthened by a society of nations organized under international law and cosmopolitanism.