World War I. The discovery of penicillin. The AIDS epidemic. The development of the World Wide Web. The dissolution of the USSR. The attacks on the World Trade Center in New York on 11 September 2001. The financial crashes of 1987 and 2008. The Indian Ocean earthquake and tsunami of 2004. Donald Trump’s win in the 2016 US election. The Covid-19 pandemic of 2020. All events within living memory to which the label of ‘black swan’ has been applied.
‘The black swan theory’ posits that the events that have the deepest impact on society and history are those that are unpredictable or highly improbable. Developed by writer and former risk analyst Nassim Nicholas Taleb in his influential 2007 book The Black Swan: The Impact of the Highly Improbable, the theory proposes that almost all of the most ‘consequential’ events in history are unexpected, and that humans only later convince themselves that these events are explainable. Taleb regards most major scientific discoveries, historical events and even artistic accomplishments as ‘black swans’ – both consequential and unpredicted. The notion of ‘our blindness with respect to randomness, particularly large deviations’ summarises the central idea of his thesis.01
The term ‘black swan’ derives from the Latin expression rara avis in terris nigroque simillima cygno (a rare bird in the lands and very much like a black swan) to describe something so rare or improbable as to have precluded contemplation of its existence prior to its appearance; when the Latin phrase was coined, black swans were presumed not to exist at all. Indeed, all known swans (and therefore in the public imaginary all swans) were white until a black variety was discovered in Australia by Dutch explorer Willem de Vlamingh in 1697. As Taleb puts it, before this discovery the idea that all swans were white was:
an unassailable belief as it seemed completely confirmed by empirical evidence. The sighting of the first black swan […] illustrates a severe limitation to our learning from observations or experience and the fragility of our knowledge. One single observation can invalidate a general statement derived from millennia of confirmatory sightings of millions of white swans. All you need is one single (and, I am told, quite ugly) black bird.02
Thus, the infallibility of a ‘known fact’ was undone once its fundamental postulate was disproved. The black swan is an oft-cited reference in philosophical discussions of the improbable. 03 Since the observation of the first black swan represented the undoing of an entire epistemology – the belief in empirical evidence as a guarantee of human knowledge – the metaphor, when applied to other instances of the unexpected, points to the black swan’s exposure of the limitations of human knowledge.
Taleb’s theory ultimately aims to make a claim about the human condition – specifically the rationality of the modern human mind in processing our known universe. ‘Histories and society do not crawl’, he writes, ‘[t]hey make jumps. They go from fracture to fracture, with few vibrations in between. Yet we (and historians) like to believe in the predictable, small incremental progressions.’ 04 It is in undermining this kind of thinking, which Taleb takes to be a structuring principle of most societies, that the black swan exposes the fragile nature of thought systems in general. Though societies, he observes, adopt a general pretence towards progress, the unsoundness of dominant thought paradigms can lead not only to life-changing innovations, but also to great inequalities and violence. The human tendency, Taleb argues, is to paper over the unknown, and to create narrative fallacies with the things we recognise. ‘We do not spontaneously learn that we don’t learn that we don’t learn.’05
