The gap between third-person, scientific, publically shared investigations, such as the neuroscience of echolocation, and first-person subjective experiencing such as echolocation-based subjective perception, has been described as an explanatory gap. Although one may know about echolocation, one does not know what it is like to perceive the world through echolocation. It is commonly argued that the explanation of the subjective feel of echolocation through the third person science of echolocation is a “hard problem”, intractable by science as we know it.
We challenge this assumption. We believe that in theory, one can, through third-person scientific investigations, attain a deep understanding of the biological dynamics of perception through echolocation (for example), which can allow one to implement it in one’s brain by using sophisticated cognitive technologies, and experience what it is like. But how can one get to this deep, bridging, understanding? In our book, The Evolution of the Sensitive Soul, we try to uncover the biological nature of experiencing by using an evolutionary approach. We suggest that the nature of consciousness, like the nature of life, can be revealed by studying its evolutionary origins.
We chose an evolutionary transition approach because if one can locate when and how in evolutionary history the transition from an organism that did not manifest consciousness to one that did, had occurred, it becomes possible to explore the processes and organizational principles involved in a “clean”way. With the study of the earliest, minimal consciousness, we will not be misled by later derived evolutionary dissociations and integrations that mask the fundamental properties of subjective experiencing.We investigate the transition from non-conscious to conscious animals by employing a methodology similar to that used by scientists who analyzed the transition from non-living to living entities. We characterize the essential features and dynamics of minimal consciousness, and single out a diagnostic, tractable, biological capacity – an evolutionary marker of consciousness – which entailed the evolution of consciousness. The identification of the marker enables the reverse-engineering of the type of system that has all the essential features of a minimally conscious system. The marker is used as an Archimedean point to explore the biological nature of subjective feelings and perceptions, the “sensitive soul” of animals.
We propose that the evolutionary transition marker for consciousness is unlimited (open-ended) associative learning (UAL). According to our analysis, UAL was the phylogenetically earliest manifestation and the driver of the evolution of sustainable minimal consciousness. UAL refers to an organism’s ability to attach motivational value to a compound, multi-featured stimulus or a new action pattern, and to use it as the basis for future learning. UAL is a good transition marker because the features that neurobiologists and philosophers regard as essential for consciousness are also required for UAL. If UAL is accepted as a transition marker, one can identify this capacity in different taxa and provide an account of the distribution of consciousness in the animal world – a major issue with important biological and ethical implications. There is evidence that this learning ability first emerged during the Cambrian 540 million years ago in vertebrates and arthropods. It was probably one of the factors that drove the great Cambrian explosion, when most animal phyla made their first appearance.
The functional architecture of UAL, which, we argue, is the architecture underlying the simplest mental representations, can be found in vertebrates, arthropods and mollusks. Learning and consciousness, however, continued to evolve. Once in place, minimal consciousness was the basis on which richer conscious life evolved, that of “Popperian”animals, creatures endowed with imagination. A further stage in the evolution of consciousness was the transition to the human “rational soul”, to human symbol-based cognition and consciousness and to the abstract values that are the basis of our ethical commitments.