Use to think analytically versus emotionally.
The last mental model about thinking clearly and not being fooled has to do with how our brain functions - on its own, not in a way that we would usually prefer.
The brain is a wonder of biology. However, just like the rest of us, it prefers to save its energy and take the path of least resistance whenever possible. To do so, the brain downgrades some of its processes and downright skips others so it can conserve energy. This means that it's always seeking shortcuts so we don't have to think through every last thing. In reality, the brain ends up cutting corners, and this leads us to make mistakes on a daily basis.
Over the years, this has led to two biological systems of thought - one focused on speed and conservation of energy and the other focused on accuracy and analysis. This is something we must be vigilant about, especially when we are introduced to new information or concepts. The brain would rather save energy for dangerous situations, but little does it realize that it can actually cause them by flawed thinking.
This concept was popularized by professor Daniel Kahneman in his seminal book Thinking Fast & Slow. Through a series of experiments, Kahneman developed a model that explains the separate processes the brain uses to absorb and react to various bits of information, imaginatively titled System 1 thinking and System 2 thinking.
System 1 is "fast" thinking. This mode is automatic and instinctive. It's what we use when we happen upon a situation that we're familiar with and don't need to process that much, like recognizing a friend, riding a bicycle, or doing single-digit math calculations. Since it's intuitive, System 1 thinking is also associated with emotional reactions, like crying or laughing when seeing an old photograph. The fight-or-flight instinct fits right into System 1 thinking.
The main facet of System 1 thinking is effortlessness. It doesn't require anything in the way of analysis or consideration, instead using a framework of associations that we've already experienced time and time again. System 1 is a series of mental shortcuts - called heuristics - that help us decode situations very quickly (more on those soon). And because there's little time or effort used in System 1 thinking, it expends less energy and isn't terribly exhausting. You're not going to need a list of pros and cons to make decisions with System 1. Although System 1 is faster, it's aimed at doing the fast thing versus the right thing.
You may have heard the term cognitive bias before - they result precisely from System 1 taking over.
System 2, on the other hand, is "slow" thinking. This is the mental model that we are seeking to use more, as it is much more contemplative and analytical. It's used for any situation that requires more mental labor and effort. System 2 is used for decision-making in events that could result in high consequences, like choosing a college, buying a new car, or quitting your job.
You also use System 2 when you're doing something that needs more focus or effort, like driving through a foggy night, striving to hear someone speak in a noisy room, trying to recall a conversation you had a few weeks ago, or learning a complex school subject that's new to you.
Where System 1 thinking is fluent and instinctive, System 2 thinking is the opposite: it's deliberate, conscious, and methodical. System 1 thinking is the proverbial skydiver, where System 2 thinking is the proverbial cautious lawyer. System 2 needs time and labor to process new information - and as a result, it uses more brain energy and can be tiring or draining. That flustered and fatigued feeling you might get while studying or reading a book isn't because you can't understand it or are bored; it's an actual biological imperative.
You're using up your System 2 energy, and that's why we always default to System 1. That's a shame because it makes us susceptible to accepting things at first glance, not thinking skeptically, being more gullible, and overall thinking in faulty ways. It also makes us impulsive and rash without considering consequences or implications. Overall, we become more primal and dumber.
For things you encounter on a regular basis or have deep familiarity with, it's great - this is where System 1 thinking shines. If you have a plethora of experience with it, it can indeed help you make a good decision. It's also obviously useful when dangerous or fearful elements are present, as System 1 thinking springs you into action where analysis and careful consideration would leave you dead.
There's a time and place for both System 1 and 2 thinking, but in the absence of dangerous, life and death situations, System 2 is preferable for clear thinking.
We can't use it all the time because it would be impractical and too time-consuming. But more importantly, it's plain exhausting, especially if you have to keep forcing yourself to do it. In truth, this should perhaps be the first mental model you should invoke when you realize you need to remain unbiased and think clearly. Being stuck in System 1 will limit just about every deeper train of thought you could have.
