David Hume's Philosophy: Empiricism, Knowledge, and Metaphysical Critiques

Hume's Empiricism: Rejecting Innatism

David Hume's philosophy defends the view that all contents of the mind are derived from experience, leading him to reject innatism.

Hume's Theory of Perceptions

Perceptions are the contents of our mind and can be divided into two major classes:

• Impressions

  Impressions are the immediate, vivid data of experience, irreducible and basic. They are strong perceptions received through the senses.

  • Simple Impressions

    These are feelings that come directly to our understanding and cannot be decomposed into parts.

  • Complex Impressions

    Complex impressions are combinations of simple impressions, but derived from simple ideas.

• Ideas

  Ideas are copies of impressions in our minds. They are weaker perceptions.

  • Simple Ideas

    These are ideas that derive directly from simple impressions.

  • Complex Ideas

    Complex ideas are unions of simple ideas. These ideas are the weakest and provide the least knowledge.

Hume's Two Types of Knowledge

Hume argues that we can distinguish two types of knowledge propositions:

• Matters of Fact

  These are based on and derived from impressions. They concern the reality of facts and form the basis of empirical sciences. Denying any matter of fact does not involve a contradiction.

• Relations of Ideas

  This knowledge belongs to formal sciences (e.g., mathematics, logic). Their negation is contradictory. They are necessarily true or necessarily false.

Critique of Metaphysical Concepts

Hume critically examines two major metaphysical concepts: substance and causality.

• Critique of Substance

  Hume concludes that the concept of substance does not derive from any impression, meaning it yields no valid knowledge.

  • Material Substance

    Hume does not deny the possible existence of material things, but argues that we are unable to prove it. We cannot perceive or know material substance beyond our perceptions. The belief in material substance is derived from custom, as certain impressions appear to be repeated regularly.

  • Thinking Substance (Personal Identity)

    Hume critiques the idea of a thinking substance, arguing that the idea of a constant personal identity is not derived from any single impression. We have no perception of a constant "self." The only impressions we have are separate and fleeting. Therefore, the existence of a self distinct from these perceptions cannot be derived from such impressions. Personal identity is a product of a mistaken belief in a succession of different perceptions combined. It is a belief that identity is formed in the imagination, aided by memory.

  • Divine Substance

    Hume states that the idea of God is beyond our perceptions. Since all we can know are our perceptions, this implies we cannot know either the existence or the qualities of God. The idea of God is considered a belief of the imagination, albeit a useful one.

• Critique of Causality

  Hume understands causality as the connection between two events: cause and effect. He argues that causality is not an empirically verifiable fact, nor a rational principle, nor a fundamental natural law. Instead, causality is a mental habit of the subject, a form of our thinking developed through repeated experience. It is produced by a belief that, upon experiencing certain facts repeatedly and invariably, the imagination leads us to think that the first causes the second, thus becoming a mental habit. We merely observe constant conjunctions between sequences of events.