Hume’s Philosophy: Perceptions, Ideas, and Knowledge
Hume’s Theory of Knowledge
1. Perceptions
Hume uses the term perception to refer to both the contents of consciousness (ideas) and the acts in which such content is presented (impressions). This aligns with the empiricist principle that reduces all knowledge to perception, which, combined with the concept of the mind as a blank slate, leads to skepticism.
- Impressions: These are the immediate acts of experience. They can be either external or internal.
- Impressions of sensation: Through these, we perceive the qualities of objects in the world.
- Impressions of reflection: Through these, we become aware of our internal states of consciousness.
- Ideas: These are reflections of a passion or an object that is not present. In other words, they are copies or imprints derived from impressions after they have faded. Therefore, ideas do not introduce any new knowledge content beyond what was given by the corresponding impression. They differ from impressions in that they are weaker and can appear in a different temporal order.
2. Types of Knowledge
After distinguishing the elements of knowledge, Hume outlines two types of knowledge: relations of ideas and matters of fact.
- Knowledge of relations of ideas: This consists of propositions that deal with pure ideas, regardless of whether they correspond to any real-world content. These relations arise from the relationships between ideas, respecting the principle of non-contradiction. Such propositions are always true by definition and are analytic; that is, the predicate is inherent in the subject. Therefore, the propositions of logic and mathematics are the only ones of this kind, representing the only field of knowledge where certainty is possible, although this certainty comes at the cost of not saying anything about reality.
- Knowledge of matters of fact: This consists of all propositions that refer to factual information obtained from impressions. These propositions are not based on the principle of non-contradiction. Consequently, their truth cannot be established logically and must be subjected to experience. This type of proposition constitutes the empirical sciences and only generates beliefs.
Hume’s Rejection of Metaphysics
Hume rejects metaphysics, understood as the knowledge that seeks to unravel the essence of things and reach ultimate reality, because his theory of knowledge leads to its denial. Since we can only rely on our impressions, we cannot know what the impressions of sensation should be, or what value the ideas and impressions of reflection might have. We cannot have strict knowledge of external reality. Therefore, all knowledge is reduced to the pure knowledge of phenomena (what appears, what is shown).
Hume takes empiricism to its extreme, concluding that knowledge is obtained solely through impressions whose origin we do not know, nor whether they correspond to an external cause. This position, which denies the possibility of foundational knowledge, is known as skepticism, a position that partially coincides with that held by the Sophists.