In 1998, two leading researchers in the new field of consciousness, neuroscientist Christof Koch and philosopher David Chalmers, met at a bar. Koch and his mentor Francis Crick (who famously discovered the double helical structure of DNA in the 1950s) had been attempting to locate “the ‘neural correlates’ of consciousness” for about a decade (xiii). By 1998, they believed they would eventually identify the specific signatures of consciousness within the neural structures of the brain.

However, Koch’s drinking partner, Chalmers, disagreed. At a 1994 conference, Chalmers had argued that the study of consciousness was hindered by two types of problems. The first are the “easy problems,” which included finding and understanding “the workings of mental operations like learning, memory, discrimination, and perception” (xv). The second is the “hard problem” of consciousness, which is the question of “why any of these mental operations are accompanied by any conscious experience whatsoever” (xv). Chalmers argued that science (reliant on objective, quantitative data) could not at this point (and possibly ever) explain the subjective, qualitative phenomenon of consciousness.

Koch proposed a wager with Chalmers, claiming that within the next 25 years, science would find the physical origins of consciousness in the brain. The loser would buy the winner a case of wine. Years later, Pollan attended the 2023 consciousness conference in New York to witness Koch admitting defeat.

Pollan explains that science has thus far found it difficult, even impossible, to objectively study consciousness, in part because of the dualism first proposed by Galileo, who chose to separate the mind from the material world and the purview of science. His decision was motivated by the political necessity to assuage the Catholic Church and the practical necessity of limiting science to objective realities he could measure rather than subjective qualities he could not. This dualism has impacted all of Western science since, leading to an inability, even a refusal, to “deal with interiority or, really, anything but measurable outward behaviors” (xvii).

Pollan acknowledges that, despite his humanist background, he is skeptical of anything that sounds like spiritualism. He has seen science explain most aspects of reality in measurable, physical terms and suspects that it is “only a matter of time before the mystery of consciousness yields before the power of science” (xix). Or rather, he believed that at the beginning of the research for this book. He is less certain by the end.

Pollan briefly explains two of the leading theories of consciousness. The first is integrated information theory (IIT), which proposes that every moment of consciousness must be intrinsic, composed, integrated, definitive, and bounded. Moreover, for any physical system to generate these qualities, it must “exhibit a certain kind of (massive) interconnectivity and recursiveness” (xxii). Crucially, proponents of IIT do not believe this is unique to brains but rather can be achieved by any physical system that integrates information.

The second theory is global workspace theory (GWT), which suggests that a brain is made of many networks or modules that process information largely unconsciously. According to this theory, information produced in each module, with the most important or useful information reaching the workspace, or the spotlight on a mental stage, at which point it enters one’s consciousness.

Chalmers has, in recent years, become a constructive critic of every new theory that emerges. Rather than devising his own theory, or becoming an advocate for any specific idea, he uses his philosophical reasoning to analyze and dissect various theories until they reach a dead end or fall apart. He does not believe any current prevailing theory adequately addresses the hard problem.

Consciousness is difficult to examine because it is the tool by which it is studied. Humans perceive the world through the lens of consciousness and cannot escape it. Scientists rely on an objective third-person perspective, a “view from nowhere,” (xxvii) which is impossible in a study of consciousness. The sub-field of philosophy called phenomenology instead attempts to understand the subjective, first-person experience, by looking from within. Hard scientists have only recently begun to integrate phenomenological perspectives into the scientific study of consciousness.

Pollan explores consciousness through four different dimensions: sentience, feeling, thinking, and self. By the end of his research, he finds that he understands less than when he began, his research having dispelled many preconceived notions and biases. He is less certain now than ever that science will solve the question, but he believes it can help people better appreciate their own minds and the sentience of the world around them.