David Hume’s Philosophy: Empiricism, Knowledge, Morality
David Hume’s Philosophy
Knowledge and Perception
David Hume’s philosophy aims to provide answers to fundamental questions about human nature and knowledge. Key tenets include:
- All knowledge originates from experience.
- All ideas must be traceable to impressions.
- All knowledge is a combination of ideas remaining in the mind, which are caused by impressions.
- Knowledge consists of established truths.
Having established that all knowledge comes from experience, Hume distinguishes two types of perceptions:
- Simple Impressions: These collect data directly from our senses.
- Complex Impressions: These are groupings of simple impressions.
- Simple Ideas: These are faint copies of simple impressions, retained in memory.
- Complex Ideas: These are human creations, formed by the mind’s grouping of several simple ideas, and may not have a direct analogy in the sensible world.
For Hume, all our simple ideas are initially derived from simple impressions. However, not all complex ideas are derived directly from complex impressions, as we can form ideas of things for which we have no direct impression (e.g., a golden mountain). But since all complex ideas can be broken down into simple ideas, it follows that one cannot conceive of anything that has not been given in experience. This principle is equivalent to rejecting the doctrine of innate ideas and the acceptance of concepts that have no empirical equivalent.
The human mind has the ability to recall and re-arrange ideas, making them reappear in the mind, and especially to relate them. The former (recalling ideas) is a function of memory, while the latter (relating ideas) is primarily the function of imagination.
The association of ideas depends on the imagination, which connects ideas based on certain principles.
The associative principles are: Similarity, Contiguity (in space and time), and Cause and Effect. From these principles, our complex ideas are derived, including ideas of substance, modes, and relations. The latter (ideas of relations) are formed when our mind analyzes and compares ideas.
Reasoning and Knowledge
Reasoning involves discovering relationships, which Hume categorizes into two main types:
- Relations of Ideas: These are truths discoverable by the mere operation of thought, without dependence on anything existing in the universe. They include mathematics and logic. Their truth is known by intuition (immediate apprehension) or demonstration (deduction from premises). Their denial implies a contradiction.
- Matters of Fact: These concern existence and real matters of fact, which can only be known through experience. Their truth is contingent, and their denial does not imply a contradiction. Most of our arguments about the world fall into this category.
Most of our arguments concern matters of fact. When we observe one event consistently followed by another (a cause-effect relationship), we tend to infer a necessary connection between them. However, Hume argues that there is no rational basis for this inference.
We cannot justify our belief in necessary causal connections through experience, because experience only provides us with knowledge of past conjunctions, not future ones. This is the essence of Hume’s Problem of Induction (often illustrated by the “inductive chicken” paradox).
Nor can we justify it by a mere relation of ideas, because the denial of a causal relationship does not involve any contradiction (e.g., the sun might not rise tomorrow without logical inconsistency).
Instead, Hume concludes that our expectation of future events being like past ones is guided by Custom or Habit. We are simply accustomed to relating impressions in the same order they were repeatedly presented in the past.
Our belief in the uniformity of nature, or in specific causal links, is therefore a matter of belief, grounded in the imagination’s tendency to associate constantly conjoined events.
Hume asserts that we observe no necessary connection between cause and effect, only spatial contiguity, temporal succession, and constant conjunction.
Critique of Metaphysics
Hume finds many concepts and objects of traditional metaphysics to be suspect misconceptions, as they have no corresponding impression and therefore lack valid meaning. For example:
- The External World: The idea of an external world existing independently of our perceptions is not derived from a single impression but from the constant conjunction and coherence of our impressions, which the imagination leads us to project outwards.
- The Self (or “I”): The idea of a substantial, enduring self is derived from the rapid and continuous flow of our impressions. The imagination, by associating these distinct perceptions, generates the belief in personal identity. For Hume, there is no simple, indivisible soul; the self is merely a “bundle or collection of different perceptions.”
- God: Hume critically examines arguments for God’s existence, particularly the teleological and cosmological arguments. He argues that such ideas, if they are to have meaning, must ultimately be traceable to impressions, but he remains skeptical of rational proofs for God’s existence.
- Soul/Body Dualism and Free Will: Hume questions the traditional distinction between soul and body as separate substances. Regarding free will, he argues for a form of compatibilism, where human actions are determined by motives and desires, but liberty is understood as freedom from external constraint, not freedom from causation. He rejects the notion that actions are the result of pure chance.
Thus, by demonstrating that concepts like the substantial self and the external world are fictions of the imagination, Hume aims to dissolve traditional metaphysics and adopts a moderate skepticism, limiting knowledge to what can be derived from experience.
Ethics and Moral Sense
For Hume, moral judgments cannot be rationally proven or derived solely from facts or relations of ideas. He argues against attempts to deduce “ought” from “is.”
- If moral issues were treated as relations of ideas, it would lead to absurd conclusions, as moral judgments would be purely logical and actions could not be inherently good or bad based on their consequences or human feelings.
- If treated as matters of fact, it would be impossible to empirically observe or prove the existence of “good” or “bad” as objective qualities in the world.
In short, Hume concludes that good or evil exist only in our minds when we discover a feeling of approval or disapproval towards an action. Therefore, morality depends on a “moral sense” – an internal sentiment or feeling. This proposal, which grounds moral judgments in emotions rather than reason, is known as Moral Emotivism.