Out of the Sludge: How Vertebrates Came to Have Subjective Experience

Abstract

Todd Feinberg, professor of psychiatry and neurology, and Jon Mallatt, professor of biology and medical sciences, have written a fascinating book that will both appeal to and agitate readers from a range of disciplines. The book tries to shed light on some of the more puzzling features of consciousness and in particular to bridge the infamous “explanatory gap” between neuroscience and the phenomenological features of consciousness known to philosophers as qualia—the subjective “feel” of sensory and emotional experiences. We approach this review as a pair of philosophers who believe that this so-called hard problem of consciousness is at least as likely to be a product of our current ignorance as it is to be a permanent barrier to scientific understanding of consciousness, and we regard an evolutionary approach as essential. That the book will agitate some readers is a strength, not a weakness. Feinberg and Mallatt advance several interesting hypotheses about the evolutionary origins and neurological basis of consciousness. They posit a very early origin for what they alternately refer to as “primary consciousness,” “sensory consciousness,” and “phenomenal consciousness.” They do not formally define this notion but link it to subjective, qualitative experience, which they distinguish from “higher” forms of consciousness such as “self-consciousness” and “reflective consciousness.” We think that they are right not to provide a more precise definition at this stage of scientific investigation, although some readers will surely want more to be said.