David Hume's Empiricism: Knowledge from Senses and Skepticism

Hume's Empiricist Theory of Knowledge

Hume's Theory of Knowledge, unlike others, is skeptical. This means it doubts the possibility of developing concepts of universal value based on facts that are constantly changing and transforming (e.g., the concept of 'I' or personal identity, the physical world). Hume considered the senses the only possible source for knowledge. Before him, many other philosophers linked knowledge to experience—to data obtained through the senses. This was the case, for example, with Aristotle who, against his teacher Plato, argued for sensitive experience as the origin of ideas. For Aristotle, we can only speak of the concept 'man' after knowing individual men (like Raymond or Augustine). In this sense, his approach can be considered empiricist, while Plato is much closer to the Cartesian rationalist tradition.

Skepticism vs. Naturalism

However, Aristotle was 'naturalistic' (he thought each thing naturally embodies a concept), while Hume is a skeptic. Hume believed we can never fully know things because we will always be limited by our bodily senses and our understanding, which is ultimately imperfect, though perfectible.

Empiricism vs. Rationalism: Innate Ideas

The fundamental opposition in the theory of knowledge during the modern age occurs between Descartes (rationalism) and Hume (empiricism). Ideas that Cartesians consider innate and 'clear and distinct' (meaning always certain and indubitable)—such as God or the substance of the self—have no real basis in sensitive experience for Hume. Since they do not comply with the 'copy principle' (ideas must be copies of impressions), they are considered empty ideas without content.

Hume's View on Induction

Hume, however, is not strictly an inductivist. Unlike other empiricists (like Locke) and predecessors of empiricism (like Bacon of Verulam) who were inductivists, Hume knew that induction was ultimately still a belief based on memory. According to this belief, if something has happened repeatedly, it will tend to repeat itself. But induction was still an assumption.

The Problem of Induction

That something has happened many times in the past does not logically guarantee it will continue to happen in the future. Similarly, something that has never happened does not mean it cannot begin to happen tomorrow (or in two minutes). The practice of inductivism, therefore, relies on an assumption rather than logical certainty.

Induction as Habit or Belief

Human nature is such that when something is repeated often, we develop an expectation that it will happen again. But relying solely on inductivism is simply a 'guess'. For Hume, the only basis for belief in scientific continuity is the coherence of perceptions, but we can have no absolute guarantee of this continuity.