David Hume: Impressions and Ideas in Human Knowledge

Elements of Human Knowledge: Impressions and Ideas

The explanation of the limits of human knowledge requires investigating the understanding to define its structure, elements, functions, and scope. David Hume applied to the mind the feat accomplished by Isaac Newton in physics. Hume posits that the contents of the mind are perceptions, which fall into two classes: Impressions and Ideas.

Distinguishing Impressions and Ideas

The primary difference between these two lies in the degree of vitality, strength, or intensity with which they are presented to consciousness:

• Impressions: These are more vivid and represent all our sensations, passions, and emotions as they make their first appearance in the soul.
• Ideas: These are weaker, serving as copies of impressions. They encompass all thoughts and memories used to reason.

In specific situations, such as dreams or hallucinations, ideas may be mistaken for impressions. Both categories can be further classified as simple or complex.

Simple vs. Complex Perceptions

Complex perceptions can be divided into simple components, whereas simple perceptions cannot. For example, the perception of an orange is a complex impression that can be broken down into color, smell, and taste. The color itself is a simple impression because it cannot be further divided. Similarly, the immediate taste of an orange is a simple impression, while the memory of that taste is a simple idea.

The Relationship Between Impressions and Ideas

Hume asserts that every simple idea corresponds to a simple impression. Because impressions precede ideas, they act as the cause of the latter. For instance, a person who has never experienced a specific color or flavor cannot form an idea of it without prior sensory experience.

Empirical Criteria of Meaning

Hume establishes a criterion for screening ideas to distinguish between two types:

• Lawful Ideas: Those properly formed with an ultimate basis in experience.
• Illegal Ideas: Those lacking an empirical referent, rendering them empty and meaningless.

While all ideas originate from experience, the human mind possesses innate structures and functions. Hume concludes that while impressions are original and not copied from precedent perceptions, all our ideas are derived from these foundational impressions.