The notion of the “unity of consciousness” is a highly ambiguous expression but it is often invoked in the work on the nature of conscious persons. Perhaps most common is the general notion that, from the first-person point of view, we experience the world in an integrated way and as a single phenomenal field of experience.  We might also at times refer to different aspects of a single object in experience, such as its shape and color.  This paper first describes and defines numerous senses of unity, such as object unity, subject unity, spatial unity, and temporal unity, along with some historical background.  It then engages with various disorders or psychopathologies of consciousness including cases where there seem to be breakdowns of unity or what we might call “disunities” of consciousness.  Various psychopathologies can show us how the unity of consciousness can breakdown in many different ways. Among those discussed are akinetopsia (“motion blindness”), neglect, somatoparaphrenia, agnosia, amnesia, dissociative identity disorder (DID), and synesthesia. The somewhat related and well-known “binding problem” is also discussed. Focusing on object unity, for example, when one looks at how the brain processes information, one only sees discrete regions of the cortex processing separate aspects of perceptual objects. Even different aspects of the same object, such as the color, shape, and motion of a blue ball, are processed in different parts of the visual cortex in the occipital cortex. Finally, I summarize briefly what seem to be the natural metaphysical implications of the fact that brain damage so clearly results in deficits of consciousness. Do these neural abnormalities resulting in such specific psychopathologies lend support for a materialist theory of mind or can some form dualism explain the phenomena?  

Rocco Gennaro is a Professor of Philosophy at USI. He received his doctorate from Syracuse University in 1991. Gennaro's primary research and teaching interests are in philosophy of mind/cognitive science with an emphasis in consciousness, metaphysics, early modern history of philosophy, ethics and applied ethics. He has published 11 books as a sole author or editor and over 60 articles and book chapters in these areas. Some of his published works as an author include his books The Consciousness Paradox: Consciousness Concepts, and Higher-Order Thoughts (MIT Press, 2012) and Consciousness (Routledge Press, 2017), as an editor, Disturbed Consciousness: New Essays on Psychopathologies and Theories of Consciousness (MIT Press, 2015) and The Routledge Handbook of Consciousness (2018). In 2020, he published Mind and Brain; a dialogue on the mind-body problem (Hackett Publishers, second edition) He is also the Philosophy of Mind/Cognitive Science area editor for the Internet Encyclopedia of Philosophy.