Sources of Knowledge
Perception, testimony, reason, and memory — the four channels through which we acquire knowledge, and the vulnerabilities of each.
The Four Sources of Knowledge
Almost everything you know comes through one of four channels. Perception is direct sensory experience: you see, hear, touch, taste, or smell something. Testimony is knowledge from other people: what teachers, journalists, scientists, and friends tell you. Reason is knowledge derived through logical inference: if A and B are true, C must follow. Memory preserves knowledge from the past, allowing you to accumulate experience.
In the modern information environment, testimony is overwhelmingly the dominant source. Almost nothing you know about world events comes from direct perception. You did not witness the war in Ukraine, the passage of legislation, or the latest economic data. You know about them because someone told you — through news articles, social media posts, government reports, or conversations. This means evaluating testimony is the most important epistemological skill for citizens.
