Where is the experience of red in your brain? The question was put to me by Deepak Chopra at his Sages and Scientists Symposium in Carlsbad, Calif., on March 3. A posse of presenters argued that the lack of a complete theory by neuroscientists regarding how neural activity translates into conscious experiences (such as redness) means that a physicalist approach is inadequate or wrong. The idea that subjective experience is a result of electrochemical activity remains a hypothesis, Chopra elaborated in an e-mail. It is as much of a speculation as the idea that consciousness is fundamental and that it causes brain activity and creates the properties and objects of the material world.

Where is Aunt Millie's mind when her brain dies of Alzheimer's? I countered to Chopra. Aunt Millie was an impermanent pattern of behavior of the universe and returned to the potential she emerged from, Chopra rejoined. In the philosophic framework of Eastern traditions, ego identity is an illusion and the goal of enlightenment is to transcend to a more universal nonlocal, nonmaterial identity.

The hypothesis that the brain creates consciousness, however, has vastly more evidence for it than the hypothesis that consciousness creates the brain. Damage to the fusiform gyrus of the temporal lobe, for example, causes face blindness, and stimulation of this same area causes people to see faces spontaneously. Stroke-caused damage to the visual cortex region called V1 leads to loss of conscious visual perception. Changes in conscious experience can be directly measured by functional MRI, electroencephalography and single-neuron recordings. Neuroscientists can predict human choices from brain-scanning activity before the subject is even consciously aware of the decisions made. Using brain scans alone, neuroscientists have even been able to reconstruct, on a computer screen, what someone is seeing.

Thousands of experiments confirm the hypothesis that neurochemical processes produce subjective experiences. The fact that neuroscientists are not in agreement over which physicalist theory best accounts for mind does not mean that the hypothesis that consciousness creates matter holds equal standing. In defense, Chopra sent me a 2008 paper published in Mind and Matter by University of California, Irvine, cognitive scientist Donald D. Hoffman: Conscious Realism and the Mind-Body Problem. Conscious realism asserts that the objective world, i.e., the world whose existence does not depend on the perceptions of a particular observer, consists entirely of conscious agents. Consciousness is fundamental to the cosmos and gives rise to particles and fields. It is not a latecomer in the evolutionary history of the universe, arising from complex interactions of unconscious matter and fields, Hoffman writes. Consciousness is first; matter and fields depend on it for their very existence.

Where is the evidence for consciousness being fundamental to the cosmos? Here Hoffman turns to how human observers construct the visual shapes, colors, textures and motions of objects. Our senses do not construct an approximation of physical reality in our brain, he argues, but instead operate more like a graphical user interface system that bears little to no resemblance to what actually goes on inside the computer. In Hoffman's view, our senses operate to construct reality, not to reconstruct it. Further, it does not require the hypothesis of independently existing physical objects.

How does consciousness cause matter to materialize? We are not told. Where (and how) did consciousness exist before there was matter? We are left wondering. As far as I can tell, all the evidence points in the direction of brains causing mind, but no evidence indicates reverse causality. This whole line of reasoning, in fact, seems to be based on something akin to a God of the gaps argument, where physicalist gaps are filled with nonphysicalist agents, be they omniscient deities or conscious agents.

No one denies that consciousness is a hard problem. But before we reify consciousness to the level of an independent agency capable of creating its own reality, let's give the hypotheses we do have for how brains create mind more time. Because we know for a fact that measurable consciousness dies when the brain dies, until proved otherwise, the default hypothesis must be that brains cause consciousness. I am, therefore I think.

SCIENTIFIC AMERICAN ONLINE

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