What arguments did David Hume make about human knowledge and experience?

David Hume, a central figure of the Scottish Enlightenment, approached human knowledge through the lens of empiricism, arguing that all knowledge originates in sense experience. He categorized perceptions into two types: impressions—vivid sensations or internal feelings—and ideas, which are the fainter, reflective images of those impressions.1234

Hume famously challenged the rational basis for causality and induction. He argued that we never observe a "necessary connection" between events; instead, we observe only a "constant conjunction" of occurrences. Our belief that the future will resemble the past—or that fire will continue to cause heat—is not derived from reason but is a product of "mental habit" and the association of ideas.541

Consequently, Hume concluded that no theory of reality is possible beyond experience, and he famously described the mind not as a unified self, but as a "bundle of perceptions". His skepticism regarding these fundamental principles created a philosophical crisis that significantly influenced the trajectory of modern philosophy.126