Gerald Edelman - Theory of Consciousness

Theory of Consciousness

Edelman is noted for his theory of consciousness, which he has documented in a trilogy of technical books, and in several subsequent books written for a general audience including Bright Air, Brilliant Fire (1992), A Universe of Consciousness (2001, with Giulio Tononi), Wider than the Sky (2004) and Second Nature: Brain Science and Human Knowledge (2007).

In Second Nature Edelman defines human consciousness as being:

"... what you lose on entering a dreamless deep sleep ... deep anesthesia or coma ... what you regain after emerging from these states. experience of a unitary scene composed variably of sensory responses ... memories ... situatedness ... "

The first of Edelman's technical books, Neural Darwinism (1987) explores his theory of memory that is built around the idea of plasticity in the neural network in response to the environment. The second book, Topobiology (1988), proposes a theory of how the original neuronal network of a newborn's brain is established during development of the embryo. The Remembered Present (1990) contains an extended exposition of his theory of consciousness.

Edelman has asked whether we should attempt to construct models of functioning minds or models of brains which, through interactions with their surroundings, can develop minds. His answer is that we should make model brains and pay attention to how they interact with their environment. Edelman accepts the existence of qualia and incorporates them into his brain-based theory of consciousness. His concept of qualia attempts to avoid the pitfalls of the idea of special qualia with non-functional properties, which was criticized by Daniel Dennett.

Edelman proposes a biological theory of consciousness, based on his studies of the immune system. He explicitly locates his theory within Charles Darwin's Theory of Natural Selection, citing the key tenets of Darwin's population theory, which postulates that individual variation within species provides the basis for the natural selection that eventually leads to the evolution of new species. He rejects dualism and also dismisses newer hypotheses such as the so-called 'computational' model of consciousness, which liken the brain's functions to the operations of a computer.

Edelman argues that the mind and consciousness are wholly material and purely biological phenomena, arising from highly complex cellular processes within the brain, and that the development of consciousness and intelligence can be satisfactorily explained by Darwinian theory.

In Edelman's view, human consciousness depends on and arises from the uniquely complex physiology of the human brain:

• the vast number of neurons and associated cells in the brain
• the almost infinitely complex physiological variations in neurons (even of the same general type) and in their connections with other cells
• the massive multiple parallel reentrant connections between individual cells, and between larger neuronal groups, and so on, up to entire functional regions and beyond.

Edelman's theory is strongly anti-reductionist and seeks to explain consciousness by reference to the extraordinarily rich and complex morphology of the brain. A newborn baby's brain comprises a massive population of neurons (approx. 100 billion cells) and those that survive the initial phases of growth and development will make approximately 100 trillion connections with each other. A sample of brain tissue the size of a match head contains about a billion connections, and if we consider how these neuronal connections might be variously combined, the number of possible permutations becomes hyper-astronomical—in the order of ten followed by millions of zeros. The young brain contains many more neurons than will ultimately survive to maturity and Edelman argues that this great redundant capacity is needed because neurons are the only cells in the body that cannot be renewed and because only those cells and networks best adapted to their ultimate purpose will be selected as they organise into neuronal groups.