A Bridge Too Far? The Bottom-up Evolutionary Approach to Consciousness Science and Bridging the Explanatory Gap

On a traditional top-down experimental (TE) approach to consciousness science, researchers start by investigating consciousness in humans, or closely related living animals, and generate hypotheses about the material basis of consciousness based on evidence from experimental paradigms which aim to disentangle conscious from unconscious processing. Only afterwards do they deem it appropriate to trace back the distribution of consciousness across the animal kingdom, including consciousness’ origin. Some scholars have started pushing back against the TE-paradigm, instead arguing that an alternative bottom-up evolutionary (BE) approach to consciousness science is more promising. On this approach, researchers start by investigating the origins of consciousness and heavily rely on evolutionary reasoning to support their hypotheses. Only afterwards do they deem it appropriate to explain how primitive forms of conscious experiences gradually complexified to ultimately give rise to human consciousness. Curiously, there is a glaring difference in the way TE-proponents and BE-proponents treat the explanatory gap. Whereas TE-proponents typically bracket the explanatory gap, BE-proponents suggest that their approach can directly address it. My aim in this paper is two-fold. First, I argue that the way in which two notable BE-proponents, Peter Godfrey-Smith and Walter Veit, address the explanatory gap by trying to close (or substantially narrow) it is ultimately unconvincing. Second, and more generally, I argue that BE-proponents do not have the luxury of bracketing the explanatory gap. Specifically, if the ideas BE-proponents put forward fail to convincingly address the explanatory gap, as I argue is the case for Godfrey-Smith and Veit, then their hypotheses about the material basis and origins of consciousness lose credibility. I end the paper by tentatively suggesting that even though the gap-closing version of the BE-approach seems unconvincing, alternative versions of the BE-approach may be more promising.