But What If Were Wrong? opens with an observation and a prediction: Klosterman first reminds us that, from one age to the next, much of what humanity believes to be true turns out to be false; he then suggests that, inferably, much of what we believe to be true today will also turn out to be false in the distant future. The remaining pages unfold this simple hypothesis into a fascinating thought experiment in which the possible falsity of various orthodox scientific and cultural beliefs is postulated and the implications of that falsity explored. Which artworks trashed today, as Moby Dick and Finnegans Wake were in their time, will be treasured tomorrow? What is the twenty-first century equivalent of phrenology or Ptolemic cosmology? Or, following out Gibran's belief that, "an epoch will come when future generations will disclaim kinship with us as we disclaim kinship with the monkeys," what morally normative behaviours will be as odious to our distant descendants as slavery is to us today? There are no correct answers to these questions but the speculations Kolsterman toys with are fun to think about. One invites us to imagine a world in which humankind is forced to abandon its belief in the objective existence of a universe (following, say, the discovery that it, and we, are a simulation in a supercomputer); another, that in the deep future the television show Rosanne is studied alongside the plays of Shakespeare; or, pressing still farther ahead, that a page out of a potboiler by Grishman or Clancy has become as obscure as a papyrus of Egyptian hieroglyphs and is subject to the same scholarly analysis by future philologists. For me the most interesting section was the one in which Klosterman questioned the prevailing scientific indifference to dreams. "For most of human history," he notes, "the act of dreaming was considered highly important, almost like a spiritual interaction with a higher power." In this connection he mentions the Tibetan monks who, three thousand years ago, taught themselves to lucid dream in pursuit of enlightenment; Rene Descartes' Dream Argument and (at the, "zenith of dream seriousness") the work of Sigmund Freud and Carl Jung for whom dreams, "were everything." The paradigm, according to Klosterman, began to shift in 1924 with the discovery of the somatotopic arrangement of the brain—the discovery that there is a point-for-point correspondence between certain kinds of brain activity and specific locations on the brain. Of particular relevance to dreams was the discovery that during sleep the limbic system, which mediates emotions, is highly active while the prefrontal cortex, which controls logic, is dormant. Suddenly, the chimeric weirdness of dreaming seemed explainable by reference to brain topography, and thereafter, scientific interest in dreams continued to diminish. "The last wide-scale attempt at cataloging a database of human dreams," Klosterman writes, "dissipated in the sixties. In 1976, two Harvard psychiatrists proposed the possibility that dreams were just the by-product of the brain stem firing chaotically during sleep. Since then, the conventional scientific sentiment has become that dreams are meaningless." But what if we're wrong? It does not seem at all unreasonable to wonder, with Klosterman, whether our current assumption about the meaninglessness of dreams is a "potentially massive misjudgment." In nightly instalments, amounting to a full third of our entire lives, we all undergo multitudinous metaphysical experiences constructed by our subconscious. There are also, Klosterman tells us, dream motifs which are universal to people in all cultures—falling, drowning, losing teeth, being guided or goaded by the dead. Richard Linklater, a filmmaker with a special interest in dreams whom Klosterman interviews for the book, agrees with Klosterman and highlights a thought-provoking paradox in our scientific worldview. While neuropsychiatry continues to casually put out of court the idea that dreams connect us to other realities, astrophysics ever more frequently raises the possibility that these other realities exist—that our universe is one of innumerable others in supermassive multiverse. There is a story by Borges in which a man on death row reflects that the future never coincides with the way we envision it beforehand. He then infers, “with perverse logic,” that to foresee a detail is to prevent it from happening and spends his last night imagining horrible deaths, “so that they would not occur.” Klosterman’s book is touched by a similar sort of madness—and Klosterman is the first to admit this. But while the attempt to “foresee the unforeseeable” is hopeless I think it also has certain incidental benefits, one of which is of a piece with healthy scientific skepticism: A reminder that, however foundational a belief appears, we should remain open to the possibility that it will be turned on its head.