Chalmers’s Double-Aspect Theory of Information

Philosopher David Chalmers has proposed a “double-aspect theory of information” as an early approach to the ‘hard problem’ of consciousness (a field-defining meme that he coined and popularized). Admittedly speculative, the theory holds information as ontologically fundamental, and it offers what it states: Information with two aspects (or expressions): a physical aspect (expression) and a phenomenal (or experiential) aspect (expression) (Chalmers, 1996).

Information as a Double-Aspect Ontology

In its physical aspect, information is instantiated in physical systems, both living systems, like neurons, and artificial systems, like computers. In its phenomenal (or experiential) aspect, the same information also has an intrinsic, conscious, or awareness aspect, which is subjective experience. As Chalmers says, “It is natural to suppose that this double life of information spaces corresponds to a duality at a deep level. We might even suggest that this double realization is the key to the fundamental connection between physical processes and conscious experience.”

“This treatment of information,” he says, “brings out a crucial link between the physical and the phenomenal: whenever we find an information space realized phenomenally, we find the same information space realized physically. And when an experience realizes an information state, the same information state is realized in the experience’s physical substrate.” In other words, “Wherever there is conscious experience, there is information; where there is information, there is a potential for conscious experience… We can think of information as the common currency between the physical and the phenomenal” (Chalmers, 1996, 1995b).

Chalmers’s information, then, would be the underlying substrate of both the physical and the phenomenal realms — a “double-aspect” ontology, reflecting ideas from Spinoza to Bertrand Russell’s neutral monism. Chalmers is careful, though; he asks, “How seriously should we take the ‘double aspect’ talk? To what extent will this framework reify information, or treat it as real? Does it claim that the physical, the phenomenal, or both, are ontologically dependent on the informational?”

Link to Naturalistic Dualism

Chalmers articulates his double-aspect theory of information with his theory of naturalistic dualism as a potential solution to the hard problem. He famously argues that consciousness is not reducible to physical processes, yet it is not outside the physical world, the natural world. He resolves what seems (superficially) to be a contradiction with a “naturalistic dualism,” where physical processes give rise to — but are not identical with — phenomenal experience. It is this naturalistic dualism that is the core of Chalmers’ thinking, and his double-aspect theory of information would be a neat way of making it work.

But while naturalistic dualism must be true for the double-aspect theory of information to hold, if the double-aspect theory of information does not hold, it does not mean that naturalistic dualism is not true. Naturalistic dualism could be true and founded on some other, yet unknown mechanism or principle.