Enlightenment later

by KENT ANHARI

Will reason survive rationalism?

According to the best-known telling of the tale, Hippasus, a Pythagorean of the fifth century b.c., was drowned in the sea by his fellow philosophers while on a fishing voyage. Hippasus had disclosed a secret that, if made public, risked destroying the credibility of his school’s commitment to a cosmos governed by perfect mathematical harmony: The relationship between a diagonal of a square and its side cannot be represented as a ratio — it is “irrational.” This legend sets the stage in Irrationality: A History of the Dark Side of Reason, Justin E. H. Smith’s urgent missive to a Brahmin class wracked with anxieties about a world that seems to have lost its grip on reason.

Smith, a philosopher of science at Paris Diderot University, is motivated by an urgent sense that a milestone reassessment of the Enlightenment’s legacy, and of the role of reason in public life, is underway in the United States and elsewhere. The emergence of prominent public voices with open counter-Enlightenment sympathies — such as Steve Bannon and Peter Thiel — and the resurgence of jingoistic populism are good reasons to take notice. So too is the fierce battle being fought between self-styled defenders of the open society, such as Steven Pinker and Jordan Peterson (however tenuous their grasp of the philosophies they claim to champion), and heirs to the left-wing critical tradition that views Enlightenment ideals as instruments for the powerful to oppress the marginal.

Smith is troubled by lapses into self-destructive unreason — the erosion of trust in institutional medicine, the corrosion of political discourse, progressivism’s increasingly draconian tactics of self-policing, and the global resurgence of nationalist mythology — which he attributes to a crumbling commitment to liberal democracy. He is wary, however, of uncritical defenses of the Enlightenment’s legacy, both because making final judgments about its nebulous history is prohibitively difficult, and because champions of Enlightenment rationalism often voice facile notions about the history of Western liberalism and its rivals. Smith criticizes Peterson, for example, for failing to notice that the murderous Communist regimes of the twentieth century bear an important genealogical relationship to liberal democracies. Irrationality paints an alternative picture.

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