David Hume: Causality, Habit, and the Principles of Idea Association
Hume's Empiricism and the Problem of Causality
For Empiricism, it is impossible to have experience of a thing that has not happened. David Hume uses the example of the billiard balls to show that we cannot establish a necessary relationship between two successive events in terms of cause and effect. Causality is a product entirely unjustified in our mind, which acts guided by Custom (or Habit).
The Role of Habit and Custom
Example: Thinking that whenever there are dark clouds, rain is necessarily coming is a product of habit. However, the fact that this has happened often does not justify the belief that it will happen forever.
The Association of Ideas
Hume argues that if ideas were completely detached and unconnected, they could only be joined randomly. Through experience, Hume seeks the natural and spontaneous forces (principles) that govern the Association of Ideas, which operate in the imagination.
The Four Laws of Association
Similarity
The ability of an idea to evoke, associate, or relate to other ideas based on resemblance. Example: A portrait of a person evokes the idea of the person depicted.
Contiguity (Spatial and Temporal)
This is the ability to link or associate ideas that are close in space or time.
- Spatial Contiguity: The idea of a building evokes the idea of the streets, houses, and landscapes that surround it.
- Temporal Contiguity: The idea of night evokes the idea of day.
Cause and Effect Relationship
The ability of an idea referring to what we consider the cause of a fact to evoke, associate, or relate to the idea of what we consider its effect, and vice versa. Example: The sight of a wound evokes the idea of its cause (e.g., a knife).
Idea of Substance
Substance ideas are complex. According to the law of association by contiguity, a set of simple ideas is assigned to one simple word, which corresponds to the complex idea formed by the mind.
Hume's Critique of Rationalism and Innate Ideas
The fundamental opposition in the theory of knowledge during the Modern Age occurs between René Descartes (Rationalism) and David Hume (Empiricism).
The Copy Principle and Illegitimate Ideas
Cartesian innate ideas, considered clear and distinct (always certain and indubitable)—such as God, Substance, or the Self—have no real basis in sensitive experience for Hume. Since they do not comply with the Copy Principle (that all ideas must be derived from prior impressions), they are considered empty or ideas without content.
While Descartes believed that innate ideas are self-evident (immediate intuitions of the mind), Hume is skeptical of what we call mental content. For Hume, all ideas are merely weaker copies of impressions (perceptions). Thought, according to Hume, is not always legitimate:
- It weakens perceptions (impressions become ideas through memory).
- It can generate false or fictitious ideas (the imagination can combine simple ideas to produce complex ideas that do not correspond to observable facts), such as the ideas of God, Substance, the World, and the Self.
Ultimately, this process of illegitimate thought creates the illusion of believing that one event necessarily causes another, which is the basis of the critique of the Inductive Method.