Hume's Epistemology: Causality, Ideas, and Factual Truths

Hume's Epistemology: Relations of Ideas and Matters of Fact

Human knowledge is composed of simple ideas, impressions, and composite materials, but this composition alone does not constitute actual knowledge. Knowing means identifying properties. For example, knowledge is attributed to the "flame" when I perceive the property of "burning." Once I connect these two sets of impressions, I can state that "the flame is burning." David Hume finds that the objects of human reason can be divided into two classes:

1. Relations of Ideas

This term refers to knowledge or truth for which information does not accurately draw on experience. It is sufficient to analyze the words and their meanings. These are necessary truths that cannot be conceived otherwise. Examples include:

• "A equals A."
• "Every bachelor is an unmarried man."

2. Matters of Fact

This term refers to knowledge and truth derived from experience. They are therefore contingent—they are true, but they could have been otherwise. Examples include:

• "Today it is raining."
• "Water boils at one hundred degrees Celsius."

For Hume, all knowledge in experimental science consists of establishing these matters or factual truths.

Analysis and the Provisional Nature of Experience

Matters of Fact are more interesting and informative than Relations of Ideas. Relations of Ideas are true and reliable but do not contain useful information about the world. Matters of Fact contain useful information, but they are always provisional. The origin of this provisional nature is explained by Hume with his critique of the concept of causality. This critique is not an elimination of the concept, but rather an analysis and clarification of the concept itself.

Hume's Critique of the Idea of Cause

We start with the idea of cause and look for the corresponding impression or real reference that prevents it from being an empty and unlawful idea. Causality establishes an empirical relationship between two events: one preceding (the cause) and another succeeding (the effect), such that from the first, I can predict the second.

The Collision of Billiard Balls

Example: The collision of two billiard balls. A ball in motion is directed toward a ball at rest, collides with it, and the second ball is thrown into motion. We say that the first transmits motion to the second, and that this movement is the effect of the collision.

The mere idea of fire does not include the necessity of causing pain or burning; this we know by experience, by a "reasonably likely" expectation. However, it could be the case that the fire did not burn under certain circumstances, or that it might stop burning in the future. On these occasions, we resort to the ideas of power, strength, energy, or necessary connection to overcome the difficulty we face when we are required to find the impression corresponding to the idea of cause.

The Missing Impression

Experience, however much we analyze it, never goes beyond independent events—atoms of experience—which succeed each other. We lack the impression of a necessary connection that truly unites them as causes and effects. The idea of cause is thus reduced to a constant conjunction of objects that arises out of habit or custom. Thus, we define a cause as follows: The second object has never existed without the first object having been given.