Daichi Suzuki

The evolutionary origin of consciousness has been a growing area of study in recent years. Nevertheless, there is intense debate on whether the existence of phenomenal consciousness without the cerebral cortex is possible. The corticocentrists have an empirical advantage because we are quasi-confident that we humans are conscious and have the well-developed cortex as the site of our consciousness. However, their prejudice can be an anthropic bias similar to the anthropocentric prejudice in pre-Darwinian natural history. In this paper, I propose three basic principles to provide a conceptual basis for evolutionary studies of consciousness: the non-solipsistic principle, the evolution principle, and the anthropic principle. These principles collectively help us to avoid solipsism, anthropocentrism, and anthropomorphism to some degree, although we cannot be completely free from them. Also, the landscape metaphor associated with the anthropic principle provides an image of how different forms of consciousness can be acquired.

Homology is a fundamental concept in biology. However, the metaphysical status of homology, especially whether a homolog is a part of an individual or a member of a natural kind, is still a matter of intense debate. The proponents of the individuality view of homology criticize the natural kind view of homology by pointing out that homologs are subject to evolutionary transformation, and natural kinds do not change in the evolutionary process. Conversely, some proponents of the natural kind view of homology argue that a homolog can be construed both as a part of an individual and a member of a natural kind. They adopt the Homeostatic Property Cluster theory of natural kinds, and the theory seems to strongly support their construal. Note that this construal implies the acceptance of essentialism. However, looking back on the history of the concept of homology, we should not overlook the fact that the individuality view was proposed to reject the essentialist interpretation of homology. Moreover, the essentialist notions of natural kinds can, in our view, mislead biologists about the phenomena of homology. Consequently, we need a non-essentialist view of homology, which we name the “persistently reproducible module” view. This view highlights both the individual-like and kind-like aspects of homologs while stripping down both essentialist and anti-essentialist interpretations of homology. In this article, we articulate the PRM view of homology and explain why it is recommended over the other two views.

Feinberg and Mallatt, in their presentation of neurobiological naturalism, have suggested that visual consciousness was acquired by early vertebrates and inherited by a wide range of descendants, and that its neural basis has shifted to nonhomologous nervous structures during evolution. However, their evolutionary scenario of visual consciousness relies on the assumption that visual consciousness is closely linked with survival, which is not commonly accepted in current consciousness research. We suggest an alternative idea that visual consciousness is linked to a specific class of agency, consequently justifying their phylogenetic claim. We also examine the implication of their phylogenetic claim: visual consciousness is homologous across vertebrates, but its neural basis is not. This apparent incongruence illustrates a general phenomenon of homology, and that the resulting hierarchical view of visual consciousness and its neural basis can be straightforwardly accommodated by neurobiological naturalism. Throughout these discussions, we aim to address the potential theoretical issues in neurobiological naturalism and refine the picture illustrated by Feinberg and Mallatt regarding phylogenetic distribution and trajectories of visual consciousness.

This paper attempts to reconcile the conceptual conflict between typological and population thinking to provide a philosophical foundation for extended evolutionary synthesis. Typological thinking has been considered a pre-Darwinian, essentialist dogma incompatible with population thinking, which is the core notion of Darwinism. More recent philosophical and historical studies suggest that a non-essentialist form of typology has some advantages in the study of evolutionary biology. However, even if we adopt such an epistemological interpretation of typological thinking, there still remains an epistemological and methodological conflict between these two styles of thinking. How can we relate typological thinking with population thinking in pursuit of more integrated or interconnected research into evolutionary biology? I propose that homology thinking, which is another style of thinking that recognizes homologous characters, provides a common basis for typological representations of character states and for character dynamics in an evolving population. Good examples of this bridging role are found in teratology and breeding, where variation and novelty are recognized in developmental and morphological traits, gene expression patterns, and so on. Essentialism-free, dynamic views of homology have great potential to reconcile typological and population thinking and to set the stage for the EES.