I met Christof Koch in 1994 at the first of series of big conferences on consciousness held in Tucson, Ariz. A professor at Caltech, Koch had helped popularize consciousness as a topic for serious scientific investigation—instead of windy philosophical supposition—through his collaboration with the great Francis Crick, who had already cracked the genetic code and now wanted to solve the riddle of mind as well.

In Tucson Koch outlined a theory, jointly fashioned by him and Crick, that 40-hertz brain waves might be a key to consciousness. Although I was skeptical of that particular theory, I liked the hard-nosed, materialist, reductionist approach that Koch and Crick took toward consciousness. I also liked the quirky intensity that Koch brought to his scientific work.

This trait was on display in Tucson during an encounter between Koch and the philosopher David Chalmers, who proposed that consciousness is such a "hard problem" that it needs new approaches, such as one incorporating ideas from information theory. Confronting Chalmers at a cocktail party, Koch declared that Chalmers's information-based theory of consciousness was untestable and therefore useless. "Why don't you just say that when you have a brain the Holy Ghost comes down and makes you conscious!" Koch exclaimed. Such a theory was unnecessarily complicated, Chalmers responded dryly, and it would not accord with his own subjective experience. "But how do I know that your subjective experience is the same as mine?" Koch retorted. "How do I even know you're conscious?"

Koch, who since Tucson has been my go-to source on neuroscience, is still chasing the white whale of consciousness, and he describes his quest in his marvelous new book Consciousness: Confessions of a Romantic Reductionist (MIT Press). Koch interweaves a brisk update on consciousness studies—with sidebars on zombies, brain-downloading, free will, neurons that recognize Jennifer Aniston, "consciousness meters" and information theory, which Koch now apparently views more favorably—with a memoir about his personal life, which has been turbulent lately. I emailed Koch—who is still at Caltech and is also the chief scientific officer of the Allen Institute for Brain Science, which recently launched a major new initiative —with questions about his book and career.

Horgan: You seem to have written your latest book in an attempt to achieve catharsis. Did it work?

Koch: Yes, it did help me resolve a long-brewing conflict between my Catholic upbringing and faith on the one hand and my scientific view of the world on the other. And writing the book also helped me deal with a more personal crisis.

Horgan: Your late friend and colleague Francis Crick once told me that free will was an illusion. Do you share this pessimistic view?

Koch: Well, Francis was right in that the standard conception of free will, that has the soul hovering above the brain and making it "freely" decide this way or that, is an illusion. It simply does not work at the conceptual or empirical level However, more subtle readings of free will remain, as I discuss in my book. Yet we are all less free than we like to believe. What remains, though, is that I am the principal actor in my life, so I better take responsibility for my actions.

Horgan: Do you think consciousness will ever be really, totally, explained? Could the "mysterians" [who propose that consciousness is not scientifically solvable] turn out to be right?

Koch: There is no law that states that all phenomena will have an explanation that humans can apprehend or understand. But my gut feelings—based on the past several centuries of progressively ever more successful explanations of the natural world—is that there will be better and better answers to the puzzle of our existence. We are not condemned to wander forever in some sort of epistemological fog. We will know. We will understand consciousness.

Horgan: Can you tell my readers, briefly, what Integrated Information Theory is and why you think it may be the key to consciousness?

Koch: The Integrated Information Theory of consciousness of Giulio Tononi is a general and quantitative way to approach the problem of consciousness. Ultimately, science needs to explain why some systems—a healthy and awake human brain, for example—give rise to conscious sensations, to experience, while other biological networks—the immune system, for example—do not. We also need to answer questions about consciousness in severely injured brain patients, in new-born babies, in a fetus, in dogs and cats, frogs, bees and flies and in artificial creatures, in iPhones and the internet. And only an information-theoretical account of consciousness is rich and powerful enough to be able to answer those sorts of questions in a meaningful and empirically accessible manner.

Horgan: Will scientists ever crack the neural code? If so, could that lead to powerful, precise mind-reading and mind-control technologies?

Koch: Of course. In some very concrete ways, neuroscience can do so already now. You can lie inside a magnet scanner and look at one of many possible YouTube videos, and cognitive neuroscientists can infer with reasonably good chances of success what sort of movie you're watching from the blood flow pattern in your visual brain. This sort of capability will get ever more refined as time goes on.

Horgan: Is DARPA [the Defense Advanced Research Projects Agency] supporting your research at Caltech because it wants to create bionic soldiers?

Koch: No

Horgan: I'll take your word for it. Have you become a member of the Singularity cult? Because I would find that very depressing.

Koch: Most certainly not. I have an article under revision right now that provides a quantitative argument for why the belief that we will understand the brain of a mouse, let alone that of a human, within a decade is as sound as the belief that the rapture is imminent.

Horgan: Phew. Has all your research into the brain given you any insights into—or control over—your own brain, emotions, behavior?

Koch: I have stopped eating the flesh of mammals and birds, as they too share the wonders of experience with us. We are all nature's children. We all experience the pains and pleasures of life. Furthermore, the commodious literature on voluntary actions makes it quite clear that we are less free than we think we are, that our prior actions, beliefs and habits shape us in untold ways. This has made me more humble.

Horgan: Not too humble, I hope. Regarding your involvement in the new initiative of the Allen Institute for Brain Science: Do we really need another of these big brain research projects? How will this differ from, say, the Blue Brain Project?

Koch: The just-announced Brain Observatory initiative at the Allen Institute for Brain Science in Seattle is concentrating enormous resources (hundreds of millions of dollars in the first four years alone due to the unprecedented generosity of Paul Allen) and several hundred anatomists, physiologists, molecular biologists, computer scientists, physicists and engineers in a concerted team effort to understand the most complex piece of organized matter in the universe, the mammalian cerebral cortex. Neuroscience is a splintered field. Some 10,000 laboratories worldwide are pursuing distinct questions about the brain across a panoply of spatio-temporal scales and in a dizzying variety of animal species, behaviors and developmental time-points. At any large neuroscience meeting, one is struck by the pace of discovery, with 50,000 or more practitioners heading away from each other in all directions, in a sort of scientific Big Bang. Although this independence is necessary, it has prevented neuroscience from entering a more mature phase, which would involve developing common standards and collaborative projects. Neurophysiologists are more likely to use each other’s toothbrushes than each other’s data and software; physiological results are hoarded and rarely made accessible online; molecular compounds and transgenic animals are shared only after publication. All of this has made comparisons across laboratories difficult and has slowed progress. We take a different approach. In particular, as in the past, all of our data, analyses, and atlases are freely available to anybody on the planet with a browser. Think of it as an experiment in the sociology of neuroscience. Only time will tell how successful this will be. Cheers