Heuristic Thinking: Why Our Brains Take Shortcuts

by Professor Owen Epstein

June 22, 2025

Heuristics are mental shortcuts, like the autopilot mode on a plane. Instead of calculating every possible route or action, your brain relies on simple, experience-based steer through everyday choices quickly and efficiently, requiring minimal mental effort. Every day, we make thousands of decisions, around 35,000, in fact. Most pass unnoticed: turning left instead of right, dodging a puddle, applying the brakes and grabbing an umbrella when rain is forecast. These don’t require deep thought. They’re handled by the brain’s autopilot, fast, effortless, and efficient.

But try solving 93 times 74, and you’ll feel the shift. That task demands effort. So how do we manage the flood of daily decisions without burning out?

In the 1950s, Nobel laureate Herbert Simon proposed that while we strive to make rational, well-reasoned choices, doing so for every decision would be impossibly slow. Instead, humans evolved shortcuts, what we now call heuristic thinking.

Psychologist and Nobel laureate Daniel Kahneman and his close friend and colleague Amos Tversky brought this idea to life in the 1970s. They showed that we regularly make decisions not through logic, but through intuition, gut feeling, using quick and instinctive mental rules of thumb.

These heuristics work surprisingly well, but they can also mislead us.

Take the “availability” heuristic. We judge risk based on how easily we recall examples. That’s why people fear flying more than driving. Driving is risky and flying disasters rare but dramatic, and media coverage makes them feel frequent. Our brains confuse memorable with likely.

Then there's the “representativeness” heuristic when we judge based on stereotypes. Take the commonly televised scene of the U.S. President stepping out of the White House toward a large and noisy waiting helicopter. This presidential “visual slogan” conveys confidence and power, readily overriding a more sober analysis of their actual leadership.

Our emotions also play a part. Kahneman called this the “affect” heuristic. When we’re in a good mood, we underestimate risks. When we’re anxious or pessimistic, we do the opposite. Our feelings shape our perception of reality, often without us realising it.

Kahneman summed this up with a simple model: System 1 and System 2 thinking.

System 1 is fast, intuitive, and automatic. It helps us navigate daily life and was honed through evolution to keep us safe. But it’s also where biases thrive.

System 2 is slow, deliberate, and thoughtful. It’s where real reasoning happens, but this takes time and considerable effort, and most often we avoid it unless absolutely necessary.

So why does this matter?

Around 60,000 years ago, Homo sapiens experienced a cognitive awakening, a mental ignition that set us apart from every other species. Our fast, intuitive System 1 thinking served us brilliantly on the African savannas, where split-second decisions meant the difference between eating and being eaten. But this evolutionary autopilot, so well-suited to spotting predators in the brush, now struggles to keep pace with the complexities of modern life. In today’s world of volatile markets, tangled geo-politics, advanced medicine, an ageing population, AI, and a climate in crisis, our reflexive thinking is poorly adaptive and so often steers us into error.

To understand where things go wrong, we must recognise how the brain’s heuristics, its shortcuts, can mislead us. It's like driving a familiar country road at speed, only to find ourselves in a dense, unfamiliar city. If we don’t learn to ease off the accelerator and engage with our slower, more deliberate System 2, we risk getting lost. Google Maps now substitutes for the System 2 task of map reading from the legendary London “A to Z” Road Atlas, and increasingly we trust what Harari call “Alien Intelligence”, to replace System 2?

Heuristics got us through the forest. But to navigate the future, we’ll need a new kind of compass, one that lets us pause, reflect, and chart a wiser course. Or do we let AI do the business? Food for slow thinking.