The Accretive View of Consciousness: Phenomenal Gradation in Ontogeny and Phylogeny

Abstract

The problem of other minds takes an especially acute form in thorny comparative cases, when we ask whether an infant is more, less, or differently conscious than an adult, or whether an octopus is more, less, or differently conscious than a dog. These judgments must be made in the absence of a settled theory of consciousness while navigating significant empirical uncertainties. For all these reasons, inference to the best explanation is the appropriate method. Drawing on convergent evidence from infant and animal consciousness research, we defend the Accretive View of Consciousness (AVC): phenomenal consciousness varies by degree and, very plausibly, along several partly independent dimensions at once, developing and differing through staged accretion across ontogeny and phylogeny. From AVC we derive the Accretive Default (AD): in hard cases, where markers are unreliable and the evidence underdetermined, the graded, profile-sensitive interpretation should serve as our default epistemic stance and working hypothesis. The operative question then is not only whether a system is conscious, but along which dimensions, and to what degree. We show that AD holds whichever way current disputes over vagueness and conceivability are resolved; that leading theories of consciousness accommodate gradation in different ways; and that the cases at issue (infants, animals, altered and atypical states, artificial and possible alien minds) do not lie at the exotic margins but very nearly everywhere we look. We also expose the pressure this places on fact-sensitive ethical theories, and indicate pathways forward for frontier consciousness science.