Justin E. H. Smith, Irrationality: A History of the Dark Side of Reason. Princeton NJ, Princeton University Press, 2019, 344 p., 16.2 × 23.6 cm, ISBN 978-0-69118-966-6

In Process and Reality (1929), Alfred North Whitehead stated that human beings are “only intermittently rational”; we are “merely liable to rationality,” and the broad claim that “all men are rational” is “palpably false.” Even longer ago, Plato noted in the Republic that the rational part of human nature, whether on the level of society or in just one individual, is its smallest part (the “true pilot” who will never have the opportunity to guide the ship; though reason is capable of leading our less-rational parts, this is neither obvious nor often true). Yet our rationality has been embraced by many other writers and thinkers, who pride themselves in their ability to reason and even elevate this power to an almost divine status, confident in its power to save us from the forces which threaten us. Carl Sagan, the American astronomer and popularizer of science, wrote the following in the book before he died: Sagan’s sense of urgency is clear: reason, the scientific method, and the embrace of logic are humankind’s salvation; the forces of superstition and irrationality spell doom for our world and all of humankind’s enterprises. Sagan’s point of view eliminates the middle ground (one is either on the side of reason or against it). But Sagan builds his case, and never loses sight of a single, simple rule: follow the evidence. This keeps him clear and focused, and never allows him to lose sight of his point. For a number of reasons, Justin E.H. Smith’s recent book, Irrationality: A History of the Dark Side of Reason (2019) is the antithesis of Carl Sagan’s book. For one thing, Smith is less than convinced in the power of reason to save humankind; unlike Sagan, he does not see rationality as the antidote to irrationality or ignorance. Rather, Smith sees irrationality as the result of reason, as much as reason emerges from irrationality (take the titular candle from Sagan’s book; rather than a light eliminating the shadows of ignorance, Smith sees irrationality as the shadow cast by the candle). The relationship the two share is dialectical, rather than necessarily adversarial. Each one contains its opposite, and when pushed far enough, one can devolve into the other (an easy example might be Nazi Germany: technologically advanced, but promoting and based upon an irrational, hate-fueled ideology), and being too intent on the pursuit of reason can lead to its loss. One’s approach to, and understanding of, an idea or phenomenon might affect what can be understood as “rational”; a particularly interesting example concerns dreams, to which Smith devotes his discussion in the third chapter. Smith contrasts three examples. The Iroquois people, who have long believed dreams provided wisdom and guidance against the uncertainties of waking life (pp. 74-75), while Rene Descartes saw dreams as deceptions (hallucinations or lies generated by the mind, p. 76). Finally, in the nineteenth century, Smith tells of how Sigmund Freud regarded dreams as a means to a new kind of truth about the self: a window into the unconscious mind (pp. 77-78). Clearly, the idea that there is truth to be gleaned from the study of dreams may be both rational and irrational, and the nature of that truth can vary in kind, as well. In addition to the above-mentioned chapter on dreams, with its numerous examples, Smith discusses a diverse (even bewildering) number of other topics. Chapters 1 and 2 question the very nature/importance/presence of reason in so-called rational societies; examples cited include a discussion of classical Greece, which Smith describes as less a bastion of reason or democratic values than a collection of what he …