The Map of Thought: Everything About Reasoning for Better Decisions

How do we think, get fooled, and reach better conclusions?

• Understand the three key reasoning tools in our mind’s “toolbox” (deduction, induction, abduction).
• Learn through concrete examples how heuristics and cognitive biases deceive our judgment.
• Gain practical exercises to strengthen your thinking muscles that you can apply immediately in daily life.

What does the detective in my mind do every day?

“My friend is unusually quiet today, is something wrong?”, “Did I eat something bad yesterday? My stomach feels strange.” From the moment we wake up until we fall asleep, we constantly think, judge, and draw conclusions. Facing over 150 decision moments daily, our brain strives to connect scattered pieces of information to understand the world.

This mental activity of deriving new conclusions based on given information is called reasoning. But how exactly does our brain accomplish this? This article unfolds the map of our thoughts, exploring the amazing tools hidden within, shortcuts that save time, and sometimes dangerous paths that trap us.

The toolbox of thought: 3 core reasoning methods

Inside our mind is a powerful “toolbox” filled with tools to understand the world. Logicians broadly classify these tools into deduction, induction, and abduction. These terms may sound unfamiliar, but in fact, we already use these tools skillfully in everyday life.

Thinking like Sherlock Holmes: Deductive Reasoning

Deduction is the most certain and logical thinking tool. It starts from a proven general rule (major premise) and applies it to a specific case to derive a conclusion that must be true—a top-down approach. If the premises are true, the conclusion is guaranteed.

• Rule: All humans are mortal.
• Case: Socrates is a human.
• Conclusion: Therefore, Socrates is mortal.

Deduction is very powerful when deriving logical conclusions within clear rules, such as legal interpretation or computer programming. However, it only clarifies facts already included in the premises and cannot create entirely new knowledge.

Thinking like a scientist: Inductive Reasoning

Induction is the opposite, a bottom-up approach. It collects multiple specific cases or observations and derives general principles or laws hidden within patterns.

• Case 1: The pasta I ate at this restaurant was delicious.
• Case 2: My friend said the pizza there was excellent.
• Case 3: Most online reviews are positive.
• Generalization: Therefore, this restaurant is probably a good place to eat.

Inductive conclusions are not 100% certain but based on probability—“likely so.” It helps create new theories and predict the future but has the weakness that a single counterexample can undermine the conclusion.

Thinking like a doctor: Abductive Reasoning

Abduction is reasoning that finds the most plausible explanation or best hypothesis based on limited clues. It infers causes from observed effects, similar to a detective or doctor’s diagnostic process.

For example, if you come home to find the trash can overturned and the floor messy, you might hypothesize, “Probably our dog did it.” This is abduction. It plays an important role by providing creative hypotheses as starting points for problem-solving.

Are mental shortcuts, heuristics, really safe?

In the flood of daily information and choices, our brain uses clever “mental shortcuts,” called heuristics in psychology. They are very useful tools but sometimes lead us astray.

Why are planes scarier than cars?: Availability Heuristic

The availability heuristic is the tendency to judge the frequency or likelihood of an event based on how easily examples come to mind.

Statistically, car accident deaths are much higher, but many fear flying more. Plane crashes receive extensive media coverage, leaving a strong impression in our minds. Thus, easily “available” memories heavily influence our risk perception.

The illusion of “knowing at a glance”: Representativeness Heuristic

The representativeness heuristic judges the probability that something belongs to a group based on how much it matches our stereotype of that group.

Seeing someone in a white coat and glasses, we easily guess “doctor” or “scientist” because it fits our typical image. This heuristic is a root of many social biases and misunderstandings.

Is first impression everything? The secret of price tags: Anchoring Effect

The anchoring effect occurs when decision-making relies too heavily on the first piece of information (anchor) encountered, causing thoughts to revolve around it.

Seeing a price tag “Regular price 100,000 won → Sale price 50,000 won,” 50,000 feels cheap because the initial 100,000 acts as an anchor raising our reference point. This principle is widely used from salary negotiations to marketing.

The traps of thought: The world of cognitive biases we fall into unknowingly

When heuristics malfunction, we fall into systematic thinking traps called cognitive biases. These are not mere mistakes but arise from structural features of our brain.

• Confirmation Bias: Tendency to see only what we want and believe only what we want. Consuming news that matches our opinions is a typical example.
• Hindsight Bias: The “I knew it all along” effect. After an event, we think we predicted it from the start, making it hard to learn from failure.
• Overconfidence Bias: Overestimating one’s judgment or ability. Experts are especially prone.
• Bandwagon Effect: Following others because “everyone is doing it.” This psychology underlies trends and market bubbles.
• Groupthink: Pressure for group harmony suppresses critical opinions, leading to irrational decisions.

These biases often trigger chain reactions. For example, negative news about a group is better remembered due to availability heuristic, then only negative information is sought due to confirmation bias. This information becomes an anchor shaping overall impressions, and if others think similarly, the bandwagon effect leads to overconfidence bias that one’s view is correct.

Building thinking muscles: Training for better reasoning

Better reasoning skills are not innate but a “skill” developed through conscious practice. The key is to slow down fast, intuitive thinking (System 1) and activate careful, logical thinking (System 2).

I personally developed the habit of deliberately asking myself, “If I am wrong, what might be the reason?” This small question helped me escape the trap of confirmation bias and gain a more objective perspective.

Comparison: The 3 reasoning methods at a glance

Checklist: Daily training for better reasoning

1. Improve quality of information:

   • Read widely across various fields.
   • Intentionally read articles with opposing views to your own (to prevent confirmation bias).
   • Always check if the source of information is reliable.

2. Externalize your thinking:

   • Ask “Why?” five times to find the root cause of a problem.
   • Write down your thoughts to clarify logical flow.
   • Explain your reasoning to others to discover gaps.

3. Practice logic daily:

   • Practice distinguishing between “facts” and “opinions” when receiving information.
   • Enjoy logic games like Sudoku or chess.
   • Treat your strong beliefs as “hypotheses” needing verification, not absolute truths.

Conclusion

We explored how our brain understands the world through the map of thought.

• Key point 1: We use three powerful reasoning tools—deduction, induction, and abduction—to draw logical conclusions.
• Key point 2: Mental shortcuts called heuristics are fast but can lead to systematic traps known as cognitive biases.
• Key point 3: Better reasoning is not innate but a skill that can be significantly improved through conscious training and practice.

This is not a destination but a lifelong practice. Why not pick one item from the checklist and try it for a week starting today? Begin your enjoyable journey of cognitive self-growth.