Hume’s Empiricism: Causation, Knowledge, and Metaphysics
Hume’s Foundational Distinction
To understand David Hume’s significant critique of causation, one must first grasp his distinction between two types of propositions: relations of ideas and matters of fact.
Relations of Ideas
Relations of ideas are propositions independent of factual existence, concerning logic and mathematics. These propositions are analytically true (necessary), meaning their truth is derived from the concepts themselves, and their denial results in a contradiction. They are discoverable by thought alone and make no reference to the facts of the world.
Matters of Fact
Matters of fact, conversely, are propositions justified only by experience. They state something about the world but are merely probable, not absolutely certain. Unlike relations of ideas, which are certain but uninformative about reality, matters of fact refer to existence but lack absolute certainty.
Causation: The Basis of Factual Reasoning
This distinction is crucial for understanding causation. According to Hume, all reasoning concerning matters of fact, except for direct sensory experience or memory, involves causal inference. Even if we believe a causal relationship is well-grounded, our conclusions about facts extending beyond our immediate senses rely on it. Empirical sciences, like physics, depend heavily on the cause-and-effect relationship. Hume observes that our certainty about what will happen in the future is based on assuming causal relationships, yet we have no direct sensory impression of the future. Therefore, the idea of cause is fundamental to all our inferences about facts of which we currently have no impression.
Hume’s Critique of Metaphysical Beliefs
Applying these principles, Hume critiques traditional metaphysics. He argues that abstract ideas must be traceable back to sensory impressions; otherwise, they should be dismissed as potentially meaningless or superstitious.
The Idea of God
Hume criticizes the idea of God. While philosophers like Berkeley posited God as the cause of our ideas, Hume deems this inference invalid because we have no sensory impression of God. The idea itself doesn’t grant validity.
The Existence of External Reality
Regarding external reality, Hume’s position leans towards agnosticism. John Locke justified belief in an external world through a causal relationship (external reality causing our ideas). For Hume, this inference is invalid because we only experience our impressions, not a separate reality causing them. The belief that our impressions refer to an external reality is, for Hume, an unjustifiable inference based on the concept of cause. We have no experience of realities transcending our impressions. Hume neither affirms nor denies the existence of an external world, considering both positions epistemically unwarranted.
The Unanswered Question: Origin of Impressions
If neither God nor an external world can be justifiably inferred as the source, where do our impressions originate?
The Boundaries of Empiricist Knowledge
Hume’s empiricism cannot answer this fundamental question. To do so would require going beyond experience, which, according to Hume, marks the absolute limit of human knowledge. We cannot legitimately venture beyond our impressions.