There is no question that specific neural events are necessary for the generation of specific mental processes in human beings and that states of consciousness influence the brain and behavior. This has been known for decades. But are mental phenomena themselves physical in nature? Those phenomena themselves (e.g., thoughts, mental images, dreams, etc.) cannot be detected by any of the instruments of technology, which are designed to measure all known types of physical entities. And when mental events are introspectively observed, they exhibit no physical properties such as mass, spatial location or spatial dimensions. Given all the scientific and introspective evidence to the contrary, why should we assume that they are physical? Even Christof Koch, who is on the cutting edge of research into the neural correlates of consciousness (which have not yet been identified), acknowledges, “The characters of brain states and of phenomenal states appear too different to be completely reducible to each other.” So why not apply Occam’s Razor and abandon all physicalist assumptions about the nature of mental phenomena and let our theories be based primarily on rigorous, direct observation of the broadest range of states of consciousness?

Are there dimensions of consciousness that are not dependent upon brain function? As long as the scientific study of consciousness is based entirely on neural activities and human behavior, that question cannot be answered. The scope of the physicalist methodologies guarantee that only physicalist conclusions can be drawn. But it’s quite true that the burden of proof is on those who posit the existence of a brain-independent consciousness. Happily, reputable scientists at the University of Virginia, including Ian Stevenson, Jim Tucker and Bruce Greyson, are exploring evidence that may indicate the existence of such a dimension of consciousness. In so doing, they are living up to the ideal of scientific skepticism proposed by Richard Feynman: “Experimenters search most diligently, and with the greatest effort, in exactly those places where it seems most likely that we can prove our theories wrong. In other words we are trying to prove ourselves wrong as quickly as possible, because only in that way can we find progress.”

Buddhism brings to the question a discipline of mental training in samadhi, or highly focused, inwardly directed attention, that can allegedly enable the practitioner to accurately recall past-life memories. This may require years of intensive, continuous training, but it would be fascinating to make such training available to a large group of subjects and then examine any reports of past-life recall in accordance with the highest standards of scientific rigor. It is not anti-scientific to pose such hypotheses or put them to the test of experience, but it is anti-scientific to dismiss them on dogmatic grounds. Given that there is no consensual scientific definition of consciousness, no scientific means of detecting it, and an incomplete scientific understanding of the necessary and sufficient causes of consciousness, it is unscientific to ignore methods of inquiry, especially those based on direct observation, regarding the nature and origins of consciousness.

Many cognitive scientists refuse even to evaluate such evidence on the grounds that there is no mechanism for the nature of such consciousness or its interaction with the brain and behavior. It might be helpful if they recalled that it was 228 years from the time that Newton explained the law of gravity until Einstein proposed an explanation (by way of the warping of space-time) for gravity; and it was 100 years from the time that Darwin proposed his theory of evolution until Crick and Watson discovered DNA, providing the basis for a mechanical explanation for genetic mutations.

As I commented in my conversation with Steve, contemporary scientific theories of the mind and consciousness are based almost entirely on 19th century physics and 20th century evolutionary biology and neurobiology. To fully understand the antiquated nature of the current demand that mental phenomena be understood according to a mechanistic model, we don’t even need to look to the spookiness of quantum physics, with its nonlocality, probability waves, quantum entanglement, and other mysterious processes.

My point can be illustrated with a brief review of electromagnetism. James Clerk Maxwell presented his four equations describing electromagnetic phenomena in 1864. At that time it was well known that electric currents could be carried by a material medium such as a copper wire. As late as 1884, Lord Kelvin expressed the view of virtually all physicists that electromagnetic fields required a physical medium in space, known as the luminiferous ether, by which they could manifest their wave properties. “One thing we are sure of,” he commented, “and that is the reality and substantiality of the luminiferous ether.” Just three years later, the Michelson-Morley experiment provided the first strong evidence against the theory of such an ether, and this effectively undermined all mechanical explanations of electromagnetic fields in space. Such fields are not “real stuff” out there, and they can be described only in terms of mathematical abstractions. But they still interact with matter. Einstein concluded in 1938: “All assumptions concerning ether led nowhere!”

I suspect that over the coming decades we shall recognize that all assumptions that fields of consciousness must invariably be carried by a material medium likewise lead nowhere. Be that as it may, given the principle of the conservation of energy, how can anything nonphysical influence the material world? For starters, we should recall Richard Feynman’s comment: “It is important to realize that in physics today we have no knowledge of what energy is.” And the Heisenberg energy-time uncertainty principle demonstrates that violations of this conservation principle do occur, and they may have macroscopic effects in the material world.

As I make clear in my book “Contemplative Science,” I make no pretense of speaking for all schools of Buddhism. In fact, I don’t know anyone who does, so I assumed that no one would think I am trying to do so. Traditional Theravada Buddhist and Tibetan Buddhists do generally believe in reincarnation, while some Chan and Zen Buddhists do and others don’t. The earliest records of the Buddha’s teachings make it perfectly clear that he claimed to have achieved “direct knowledge” of his own and others’ past lives; and many later contemplatives have allegedly replicated his findings. This is one of the hallmarks of the contemplative science that is found in Buddhism.

Whatever our beliefs may be, questions pertaining to the nature of consciousness and its possible continuity beyond this life are not merely intellectual or metaphysical. They have an enormous bearing on our understanding of human existence and the parameters of Nature as a whole. I am not encouraging anyone to accept Buddhist hypotheses simply out of faith, nor did the Buddha himself encourage such blind belief. But I am convinced that collaborative research among psychologists, cognitive neuroscientists, and contemplatives from multiple traditions may yield a much richer, more comprehensive understanding of consciousness than any one of those disciplines by itself.