At the HowTheLightGetsIn Festival earlier this year, award-winning English novelist Joanna Kavenna, renowned public intellectual Rory Sutherland, and pioneering philosopher Rebecca Roache met to debate the limits of reason. The three thinkers discussed the ambiguous line between reason, truth, and well-being in a wide-ranging conversation replete with ideas from ancient Greek philosophy to contemporary neuroscience. Charlie Barnett explores the debate and suggests that reason is useless by itself, and in the hands of the wrong person, its application can have disastrous impacts.

Note: ‘Reason’ is used in the Enlightenment sense of analyzing a situation logically and rationally instead of falling back on tradition, dogma and authority. ‘Rationality’ is used interchangeably with ‘reason’ as is often done so in everyday use.

Reason, seemingly straightforward, is a concept fraught with difficulty. We are often told to favour the rational approach over the emotional one, tending to relegate the latter to secondary status in decision making. From political slogans like ‘facts don’t care about your feelings’, to Martin Luther King’s call for America’s laws, in a time of horrifying racism, to be ‘rational and proportionate’, we like to think that the triumph of rationality will create a better society for all.

The Ancient Greek ruler Pericles (495-429BC), heralded as one of the Great Athenian rulers, was revered for his use of reasoned argument over bluster and bravado, both in his speeches and the substance of his policy. He argued against the expansion of the Athenian empire through violence and launched small military manoeuvres to limit the loss of life. When Athens had a surplus of wealth, he commissioned temples, theatre and art, promoted rationality and beauty, and profoundly shaped Athenian culture. The renowned journalist and author Robert Greene, in his masterful book, ‘The Laws of Human Nature’, described Perciles vision of rationality as ‘our ideal’.

Similarly, we know what is not reasonable. When Putin launched his brutal invasion of Ukraine, Peter Hitchens, a journalist well-known for his condemnation of the West’s treatment of Russia after the Fall of the Soviet Union in 1991, was quick to identify him as a ‘man who’s lost his reason’ and ‘whose actions can now no longer be predicted on any basis’.

We seem to be confident in distinguishing the rational from the irrational; the reasonable from the unreasonable. In the philosophy sections of many bookstores, reams of books are dedicated to telling us how we can become more rational individuals. From ‘How to Win Every Argument: The Use and Abuse of Logic’ (Madsen Pirie), to Logic for the Left (Ben Burgis), and Rationality (Steven Pinker), the debate, for many over what rationality is, is mostly over. It is just a question of educating the masses and making sure that we apply it consistently.

But reason is not so straightforward. This much was true in a remarkable exchange between Professor Tommy Curry and Professor Massimo Pigliucci at Howthelightgetin June 2022. The subject under discussion was cosmopolitanism: the belief that citizenship should be extended to all human beings by virtue of their rationality. Pigliucci was forthright in his contention that a ‘true’ cosmopolitan could never be a fascist or a Nazi. And if they had justifications for why they were, these justifications must be wrong. Someone could never reasonably say, ‘I’m a cosmopolitan, therefore I’m entitled to kill people that don’t look like me’.