The human brain has two independent systems: an intuitive system and a rational system.
1. The intuitive system is unconscious and fast-reacting. Its advantage is speed with no mental effort; simple problems are all delegated to it.
2. The rational system is conscious thinking and analysis. It is characterized by high energy consumption and slowness, but it can solve complex problems.
Both systems play a role in human decision-making. Because System 2 is lazy, System 1 often takes the lead, but System 1's intuitive reactions easily lead to biases and errors in decisions. So Kahneman suggests we should use System 2 to compensate for System 1, and slow thinking to compensate for fast thinking, which helps improve the quality of our decisions.
We can understand it from another angle: use System 2 more often to train and optimize our System 1, making System 2's deep thinking the cause and System 1's fast reactions the effect. Because System 1 is the key to the differences between people.
The common gap between ordinary people mainly shows itself in situations like this: a decision or plan that requires you to think for a while, or a skill level that takes you some practice to develop, the other person can do without any thought—blurting it out, getting right to it. For example, a new driver has to think about shifting gears, the accelerator, the brakes, steering, the windshield wipers, and so on, but for an experienced driver, it's all instinct. For example, in an exam, someone who has just mastered a knowledge point still needs time to calculate, but someone who has done lots of practice problems can pick the right answer on feel. For example, when I argue with a quick-tongued person, what's the most cutting thing I could say? It takes me forever to think of it, and by then they've already cursed three generations of my family.
But for most things, if you have enough time, apparent gaps can be closed. The gap between not knowing how to drive and knowing how is huge, but you can hardly tell the difference between someone with a dozen years of experience and someone with several decades. I couldn't win an argument with him at the time, but once I lay down in bed, one sleepless night was enough for me to come up with lots of clever things to say to insult him back. Given enough time, many gaps can be smoothed over. Unfortunately, at critical moments, we don't always have that kind of time.
That's where the differences between ordinary people show: two people can both reach the same level, but one needs some time, while the other can respond instinctively. For an ordinary person, an instinctive response in a particular area isn't something you're born with; it comes from extensive practice in System 2, which eventually optimizes it into System 1. So even if I stay up all night, come up with lots of clever comebacks, and get ready to fire back, I still might not win the argument the next time I run into him. Online keyboard warriors often trade insults on fairly even terms, and an important reason is that being behind a keyboard gives them plenty of time to make up for some people's shortcomings in their System 1 responses.
By now, I believe everyone understands that given enough time, ordinary people can accomplish many things through 2 slow thinking. But in real-world situations, those who optimize their 1 well are the ones who can distinguish themselves from others. So simply understanding ideas and skills after reading about them isn’t enough. We need to think more deeply and practice more. Only when they move from effortful 2 to easy, enjoyable 1 can we truly pull ahead of others. Kahneman’s dual-system theory is not merely a description of a brain function, nor is it about praising System 2 and disparaging System 1. Rather, it helps us make good use of the characteristics of these two systems in the brain and find ways of thinking that support self-improvement.