Biological Naturalism and Biological Realismdevelopment from new-born baby to an adult, or backwards to the evolutionary past, describing
how human consciousness emerged during evolution, or how any type of consciousness at all
emerged during the evolutionary history of life on the planet.
In the case of color vision, the immediate physical stimulus might be the red traffic light lit
up in your visual stimulus field and activating the neural pathways from the eyes to the visual
cortex to area V4, until the phenomenal experience of redness emerges into perceptual con-
sciousness. The developmental explanation would explicate how the human visual brain matures
early in life to detect and discriminate various colored stimuli, and how this development fails in
color-blind individuals. The evolutionary explanation explains the ultimate origins of the abil-
ity of humans to see colors: why are we not achromatic creatures? During evolutionary history,
there were selective survival advantages in quickly and accurately recognizing colored objects,
such as ripe fruits and berries, and poisonous dangerous animals, such as snakes and hornets,
among green and brown leaves and grass. This led to highly accurate color vision being selected
for in our ancestors and many other primate species before humans.
When we have all these dimensions of explanation covered without gaps, we will have a full
mechanistic, multilevel biological explanation (of visual color experiences, for example).
Consciousness is a higher level of biological organization. The problem is that, at the moment,
there are too many missing levels in the constitutive explanation; too many gaps in our scientific
knowledge, between what we know about the neural levels in the brain and the conscious levels in
the mind to yet be able to connect them smoothly within the multilevel model. The Explanatory
Gap between consciousness and the brain follows from our ignorance of the intermediate levels,
not from any fundamental metaphysical or epistemic inability to explain consciousness.
According to BR, pure phenomenal consciousness is the basic level of consciousness. It is
a unified, spatial field or sphere where the qualities of experience come into existence (I thus
agree with Searle’s unified field theory). Phenomenal consciousness is most likely based on
large-scale neuroelectrical activities and recurrent interactions in cortico-cortical and thalamo-
cortical networks.
BR (like BN) takes consciousness as a holistic, spatial phenomenon by its fundamental nature.
In BR, the spatiality of consciousness is lifted to a special status among the features of conscious-
ness: it is the very feature that crosses from third-person physical ontology to the first-person
qualitative ontology, as it has one foot in both realms. The pure spatiality of consciousness, the
phenomenal space or field, cannot be experienced as such - it does not in itself constitute a con-
tent of experience or include a phenomenal character. It is the level of organization that mediates
between the nonconscious, purely neural levels, and the conscious phenomenal levels in the
brain. Thus, it could be called the sub-phenomenal space. It is the system at the interface between
the phenomenal and nonphenomenal realms that reveals itself only indirectly, in the fact that
all the phenomenal qualities that we do experience always appear to be spatially organized within a
single unified overall context, the world-for-me.
The sub-phenomenal space must be activated for us to be in the conscious state – in the state
where all kinds of qualitative experiences are enabled. When it is not activated, as in a coma or in
dreamless sleep, we are in an unconscious state, and no experiences are possible. When it is par-
tially damaged, as in unilateral spatial neglect, no experiences are possible in the compromised
parts of sub-phenomenal space. Moreover, any direct awareness of a space that is missing from
experience is impossible to reach for the neglected patient. The unified field of consciousness
always seems like a complete spatial world for the subject, even if it fails to represent some part
of the external stimulus space because the corresponding phenomenal space itself is missing.
The sub-phenomenal level constitutively supports phenomenal qualities: they can only appear
within it. Outside the sub-phenomenal space, qualities of experience do not and cannot exist.