Thinking, Fast and Slow, Cover - Lucid

Why We Say Irrational Things

Have you ever stood in the shower at night and grimaced, thinking back on an awkward statement or brash decision you made earlier that day? Do you wonder what made you hastily do something so out of character? Well it turns out that our rash, knee-jerk and unpredictable actions are a result of two, opposing decision systems inside our head.

Thinking, Fast and Slow is a best selling book by Nobel Prize winner Daniel Kahneman, the book about human psychology encompasses his work on cognitive biases, prospect theory, and his later work on happiness. The Israeli-American psychologist is famed for findings in the psychology of judgment and decision-making, as well as behavioral economics, the latter of which earned him the 2002 Nobel Memorial Prize in the field of Economic Sciences.

Thinking, Fast and Slow challenges existing schools of thought about how humans reach decisions. Kahneman’s rich background in the field of behavioral sciences enabled him to rewrite the rule-book about thinking patterns, heuristics and biases. The title; Thinking, Fast and Slow, is a connection to the findings of the book, where Kahneman theorizes two distinct thinking systems inside every human brain:

System 1: Fast, automatic, frequent, emotional, stereotypical, subconscious

System 2: Slow, methodical, infrequent, logical, calculating, conscious

In this easy-reading book review, I’ll highlight a few of my favourite takeaways.

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Automation, Systematic

Daniel Kahneman would like us to think that all decisions can inherently be attributed to two distinct systems of mechanical thought:

System 1 is automated, quick witted, generalist, bias-driven, and makes emotional reflex decisions which are easy to reach and require little energy.

System 2 makes slow, methodical, calculative and conscious decisions, similar to those when we fill out a superannuation form or calculate sums and figures.

System 1 is designed to give us an ability to ‘case’ a situation or environment quickly and relies on general rules called heuristics. Heuristics are rules which are learned through our life experiences and are thought to also be evolutionary, as we have adapted over time by making fast judgements and actions. System 1 is present when we are in danger or face a ‘fight or flight’ scenario, this is a perfect example of when our mind needs to make a fast, instinctual decisions.

Thinking, Fast and Slow, Systems - Lucid

However, information and decisions aren’t mutually exclusive between the two systems either. Information is fired from System 1 to System 2 if it requires help, like an escalation point for when System 1 can’t work it out on its own.

A fine example of system ‘switching’ can be examined by an NFL Quarterback. When a QB receives the ball they are thinking in System 1, performing automatic, practiced body movements and stepping back to commence the play. If there is no defence encroaching on them, or ‘danger present’, they’ll switch to System 2 and analyse the play options in front of them. When they have decided on an option, they’ll run or throw the ball,  thus engaging System 1 again. This is an extreme example of how humans can switch systems in just fractions of a second.

Although System 1, is effective in protecting us from moment to moment, they are far less useful when planning anything long term, like your investment strategy. So you can see how System 1 quickly goes from fast problem solver to the root of all problems.

Kahneman states that System 2 is capable of overruling the decisions which System 1 makes, and subsequently avoiding errors of judgement. However, Kahneman also highlights that System 2 is sometimes oblivious to the fact that the heuristics that shape System 1 are also affecting System 2.  I’ll cover some of my favourite heuristics from the book further below.

Before you start blaming System 1 for it’s poor hindsight, stop short of complete condemnation – System 2 isn’t as rational we think either. Kahneman states that System 2 is ‘not a paragon of rationality’, lacks statistical insights and is poor at accurately determining probabilities. System 2 still requires a great deal of help to reach decisions, however we’re certainly able to coach it into making better ones with the right training.

The Overpowering Effect of Heuristics

Kahneman also extensively covers a number of heuristics in the book. I’ll be frank, there is a lot of System 2 thinking involved the further you flick the book, however I’ve never had to stop reading a book and analyse what I just read, as much as I did whilst reading Thinking, Fast and Slow. There is simply a goldmine of insights and thought-provoking ideas in it.

Thinking, Fast and Slow, Heuristics - Lucid

If you’re still wondering what heuristics are, well they are efficient, hard-coded rules we have learned through our existence and by evolutionary processes. They are thought to explain how people make decisions, come to judgments, and solve problems typically when facing complex problems or incomplete information.


One of my favourite forms of heuristics he covers is ‘priming’. To explain what priming is, I’ll use an experiment performed in Germany involving experienced judges and guilty shoplifters from the 1970s.

In the experiment, experienced German state judges were asked to provide sentences on convicted shoplifters. Hours before they were asked to hand down the sentence, the judges were unknowingly handed two ‘loaded’ dice (loaded dice are designed to roll certain numbers). The judges were asked to roll them repeatedly, subsequently landing on higher numbers such as 9, 10 and 11.

So what was the effects on the sentences? Well the judges which were handed loaded dice handed out longer, harsher sentences of course. This is a classic case of ‘priming’, something which was featured in the 2015 Will Smith film, Focus:

Confirmation Bias

It’s a fact of life that everyone jumps to conclusions and Kahneman would like us to believe this is another form of heuristics called ‘confirmation bias’. Confirmation bias is when we go seeking evidence to support a belief or position we have, whilst ignoring or discarding counter-evidence. This is usually prevalent in any tribalistic or dogmatic context, such as politics, religion or say, the best football team in the world (which is Arsenal of course).

The two systems play a role in our confirmation bias too. When required to make a quick decision, we’ll often look for patterns which kind of work with our initial ‘hunch’. In high-pressure or high-value scenarios, this can often result in terrible assumptions resulting in even more horrendous outcomes.

The Hindsight Illusion

“I knew that was going to happen!” is surely one of the most overused phrases known to man, and two types of people you’ll hear those words from are stockmarket analysts and gamblers, who both fall foul of the The Hindsight Illusion. Kahneman explains that our intuitions feel more realistic and true to us than facts, and we are vulnerable to forgetting what we believed before an event happened. For example, you’re sitting at the pub watching a game of football which goes into extra time, the star player scores a wondergoal from 35 yards out. At this point, it’s not uncommon to have your friend turn to you and yell “I knew he was going to score!”

The truth of The Hindsight Illusion is that your friend probably thought about 8 other players scoring during the game, but falls foul of the illusion and believes his false premonition that he saw it coming above all else.

Theory-Induced Blindness

My final heuristic will add a little balance to this article, enter Theory-Induced Blindness. Kahneman states that once we have accepted a theory as true and start to use it in our own methodology, we struggle to find errors or flaws in the theory itself.

Say you’re a stockbroker who has earned thousands of dollars using a special trading system for months, flawlessly locking in gains with every trade you make. One day your previously infallible system causes you to place a losing trade that wipes out your trading account, you sit there and assume that it’s not the system that was at fault but some external factor which can perfectly explain why it wasn’t the system’s fault.

When you finally come to the realisation that the trading system is fallible and you’re not Gordon Gecko, you’ve overcome theory-induced blindness.

Better Shower Thoughts

When I read Thinking, Fast and Slow in 2012 it took a large amount of System 2 thinking to get through it. Although it’s not an ‘easy read’ I certainly believe it helped redesigned some of my decision making patterns. From time to time I like to read book summaries to help refresh myself of the theories Kahneman covers in the book. I also can’t help but feel a little ‘helped’ by the book in a professional way, so much so that I’ve convinced a few other people to read it.

As New York times writer Jim Holt put it in his critical review of Thinking, Fast and Slow:

“It is an astonishingly rich book: lucid, profound, full of intellectual surprises and self-help value.”

Next time you jump to a conclusion and are about to say something misdirected; check yourself, switch to System 2 and say something more objective and thoughtful. Who knows, it might reduce the awkward grimacing you do in the shower later that night.

To wrap it up, here’s some wise words from Kahneman about controlling irrational tendencies:

In case you couldn’t tell, we at Lucid are passionate about body betterment, neuro-enhancement, productivity & focus. To be kept up to date on any other blogs or infographics, add yourself to our community mailing list.
Hendrik Kruizinga

Hendrik is the Co-Founder and Chief Product Officer at Lucid. He avidly pursues great design, experiential products and the a daily dose of betterment.