Hume vs. Kant: Understanding Causality and Knowledge

Hume's Radical Empiricism

David Hume, a radical empiricist, argued that all ideas must be preceded by an impression. If there is no corresponding impression, the idea is not valid. This includes the concept of causality (cause and effect). Immanuel Kant, on the other hand, stated that while everything begins with experience, not everything arises from it.

Hume believed that our perceptions had no causality at all, but were merely linked by habit. The awareness of the principle of causality comes *after* the experience of apparent causal relationships. For Kant, however, the principle of causality is fundamental and necessary for the perception of sequences of events, that is, to limit knowledge to the *a priori*. Impressions are the experience; in Kant's philosophy, knowledge is the phenomenon, which appears. The noumenon is unknowable. Synthetic *a priori* judgments must be given in experience to be considered true.

Hume called the contents of our experience perceptions, and categorized them into two types: impressions, which are our more lively perceptions when we hear, see, or feel, and ideas, which are less intense. Ideas depend on impressions (via the senses). In Kant's philosophy, the elements of knowledge are intuitions (immediate knowledge through the senses) and concepts (important pure categories and empirical concepts). Both are necessary. Intuitions without concepts are blind; concepts without intuitions are empty. Hume's philosophy is based on habit from past experience; there is no synthetic *a priori* knowledge, only *a posteriori*. In Kant's philosophy, synthetic judgments are possible *a priori*. They are universal and necessary.

Comparing Judgments and the Idea of Cause

Hume's types of knowledge are *a posteriori* and synthetic, with analytic *a priori* judgments (which do not extend knowledge). In Kant's philosophy, judgments are synthetic/analytic *a priori*. Hume criticized the idea of cause, stating it is based on past experience and converted into a belief, even if not true. For Kant, comprehensive knowledge is possible because of causality; things happen for a reason (*a priori*). Hume denied external reality because he could not explain the idea of causality. Kant accepted it because he believed in the principle of causality. External reality is unknowable, but we cannot prove that it does not exist. Being a limit on what we know in the phenomenon, we can assume that there is something beyond the limits of our knowledge.

Substance and the Self

Hume rejected the idea of substance because we have no knowledge or experience of the empirical concept of substance; everything resulting from substance (the self) would be fake. In Kant's philosophy, substance is a category added to our intellect, not something we have experienced, but thanks to it, we can understand and unify experience. For Hume, the self does not exist; nothing remains like a self, as no one has an impression of the self. In Kant's philosophy, the self as a subject is the foundation of all knowledge because it has the *a priori* structure that makes this possible. If you know, it is because you think; there is a unifying object of experience.

The Idea of God

Both Hume and Kant agree that God is unprovable. For Hume, this is because it is not based on any impression. For Kant, it goes beyond the limits of experience.