Part 1 — From Descartes’ Cogito to Chalmers’ Zombies

Why is brain activity accompanied by subjective experience? Why do certain physical and functional processes not simply unfold “in the dark,” without there being anything it is like to see a color, feel pain, or have a thought?

This is what David Chalmers famously called, in the 1990s, the hard problem of consciousness. But the problem did not suddenly appear with him. It is the outcome of a much longer transformation of the classical mind–body problem.

In this first article, I therefore propose to retrace that history. We will begin with Descartes’ dualism and the difficulty of understanding how an immaterial mind could act on a physical body. We will then follow the rise of materialism and later physicalism, the development of physiology and neuroscience, the emergence of the principle of causal closure of the physical, and finally the attempts to understand the mind through identity theory and functionalism.

This history reveals a striking paradox. As science becomes increasingly successful at explaining how the brain processes information, produces behavior, recognizes objects, uses language, or makes decisions, one question seems to become progressively isolated: why are these processes accompanied by subjective experience at all?

From Leibniz to Kripke, from nineteenth-century physiology to neuroscience and artificial intelligence, we will see how this difficulty gradually came into focus before receiving its contemporary formulation in Chalmers’ work.

This first part is mainly historical and conceptual. A second article will examine the major responses proposed to the hard problem — reductive physicalism, dualism, emergentism, illusionism, and other approaches — and will assess their respective strengths and costs.

The full article is available below as a PDF.