Daniel Kahneman shared the idea of System 1 and 2 thinking in his book Thinking, Fast and Slow (2011). System 1 thinking is the fast kind that is barely perceptible to us. The authors describe it as “the realm of automatic perceptual and cognitive operations—like those you are running right now to transform the print on this page into a meaningful sentence” (33). The ability to think in this way not only aids our day-to-day functioning but also enabled our primeval ancestors to quickly assess potential opportunities and dangers and so helped with the survival of our species.

While System 1 thinking is popular with many in the contemporary self-help movement, who talk at length about gut-knowing, the authors consider that it can be a hindrance to accurate forecasts. This is because System 1 makes us prematurely reach for the most seemingly obvious conclusions. Arguably, it was a proliferation of System 1 thinking that made people jump to the conclusion that the 2011 Oslo terrorist attack was caused by Islamists. Speculators drew upon the evidence that similar attacks in the cities of London, Madrid, and Bali had been caused by Islamists to reach a satisfying conclusion. In order to discover the truth—that the attack was caused by a single Islamophobe—investigators had to push against System 1 thinking and consider the counterevidence.