At the end of last year, I wrote an article titled “Sharing Ideas for New Products, Services, and Research Directions.” The second idea in that article was an “Automated Critical Thinking Assistant.” If I could only learn one skill, I would choose critical thinking. It’s crucial for individuals, communities, nations, and even the world. Critical thinking helps individuals avoid making poor decisions. When more people can think impartially and distinguish right from wrong, communities, countries, and even the world can engage in effective discussion and analysis of contentious issues, leading to peaceful negotiations and truly effective solutions. This avoids endless disputes, internal conflicts, and disastrous extreme policies. So over the holidays, I started looking for and reading relevant books. The first introductory book I chose was Critical Thinking Skills For Dummies.

While For Dummies books appear to be beginner-level, their quality is actually quite good. However, I found this particular book tough to get through. The chapters lacked strong logical structure, and the content often referenced a wide range of examples, making it hard to grasp the key or actionable information. It took a lot of effort for me to read it twice: a quick first read, followed by a more detailed second read to extract key points into my notes. That said, the book has plenty of valuable content — like details on Hitler’s brainwashing techniques, the biggest human flaws that lead to disasters, a practical framework for critical thinking akin to “comparison shopping,” and analyses of history’s most influential arguments. Taking advantage of a long weekend, I decided to write a detailed summary and review.

1. What Is Critical Thinking?

Critical thinking can be broadly defined as “reasonable and reflective thinking focused on deciding what to believe or do” (Norris and Ennis, 1989). More specifically, it involves gathering information before acting, analyzing and interpreting that information, and making logical conclusions based on carefully examined evidence. It requires handling information critically, challenging and analyzing data, and arriving at justifiable, evidence-based conclusions — all while avoiding logical fallacies, unfounded opinions, and subconscious biases.

The book offers a broader definition: critical thinking involves a range of skills and understandings, including verbal dexterity, sensitivity to context, feelings, and emotions, and — most challenging of all — the open-mindedness that enables creative leaps and insights.

2. The Opposite of Critical Thinking: Natural Human Thinking

The essence of education is to inspire human strengths and curb human weaknesses. Learning critical thinking essentially means correcting the biases in Natural Human Thinking. The book identifies several common types of natural thinking:

  • Stubborn thinkers: They form beliefs by rigidly sticking to their favorite initial ideas, ignoring contrary evidence or changing environments. They often rearrange their prejudices rather than rethinking.

  • Conformists: Most people fall into this category. They respect authority figures and derive their views from group discussions, teachers, or public consensus. While useful for social cohesion, they contribute little to original thinking.

  • System builders: A more complex version of the stubborn thinker. They frame everything within pre-existing mental models and resist change, even when new evidence demands a paradigm shift.

  • Total skeptics: They believe in nothing and doubt everything, often as a reaction to past gullibility. These people are unhelpful in constructive political discourse.

The author acknowledges that natural thinking has its benefits:

  1. Efficiency – Critical thinking is mentally taxing. Following authority, intuition, or consensus is often practical and effective.

  2. Social harmony – Constant disagreement and over-analysis disrupt group cohesion.

However, the downsides of conformity include:

  • Lack of understanding or justification for one’s beliefs.

  • Stifled innovation.

  • Susceptibility to manipulation.

  • Risk of serious misjudgments in personal, financial, and medical decisions.

The book references Daniel Kahneman’s Thinking, Fast and Slow, which distinguishes between:

  • System 1: Fast, intuitive, emotional thinking.

  • System 2: Slow, deliberate, logical thinking.

3. Common Tricks Used to Manipulate Public Thinking

Public relations, marketing, and political propaganda often exploit natural thinking. A detailed case study in the book is Hitler’s propaganda tactics, designed by himself and Joseph Goebbels. In Mein Kampf, Hitler lays out these methods:

  • Limit messages to a few points, repeated constantly.

  • Use emotionally resonant slogans.

  • Avoid debate.

  • Target the lowest common denominator in intelligence.

He credited the British military with teaching him this method. In short:

Brainwashing = short, dumb, emotionally charged slogans + repeated endlessly + avoid debate

Nazi propaganda thrived on prejudice — humanity’s darkest trait. Discriminating against entire groups based on identity (e.g., race, age, religion) rather than individual behavior is what made the ideology so dangerous.

Modern advertising and political messaging still employ these tricks:

  • Emotional transfer: Linking products to positive people or scenes.

  • Bandwagon effect: “Everyone is doing it.”

  • Expert authority: “Scientists agree…”

  • Vague qualifiers: “May,” “could,” “some,” etc.

  • Flattery: “You’re smart, so you deserve the best!”

4. Do You Really Want to Become a Critical Thinker?

Despite its benefits, critical thinking comes with side effects:

  • You may become disliked for unpopular opinions.

  • You may feel disillusioned upon seeing the world’s flaws.

  • You might face consequences for speaking truth to power.

Yet the benefits are significant:

  • Spot hidden flaws in mainstream views.

  • Avoid major life mistakes in health, finance, and relationships.

Ultimately, the author challenges readers: Do you want the red pill or the blue pill? Do you want to be enlightened and uncomfortable, or ignorant and happy?

5. The Self-Cultivation of a Critical Thinker

The author advocates a smart approach to the world: accept that everything you know might be wrong, and if needed, be ready to start from scratch and rebuild the reasoning. This foundational mindset underpins all critical thinking.

The specific qualities of a critical thinker include:

  • Tolerance: Willingness to hear differing viewpoints and engage in real debate. Open to new ideas and accepting of criticism.

  • Analytical skills: Rejecting arguments that are ill-structured or unscientific. Preferring logically and scientifically sound reasoning.

  • Confidence: Courage to challenge the views of others, especially those in authority.

  • Curiosity: A drive to explore new knowledge and ideas.

  • Pursuit of truth: Commitment to objective truth, even when it contradicts personal interest or long-held beliefs — a truly high standard requiring detachment from self-interest.

Not everyone is naturally suited to be a critical thinker. Our personalities differ, and traits like tolerance, analysis, confidence, curiosity, and truth-seeking vary across individuals. Without deliberate training, these traits can be hard to develop.

6. Facts vs. Opinions — The Distinction and Connection

Thinking involves processing a stream of facts and opinions to arrive at conclusions. Understanding the distinction between the two is crucial:

  • Facts: Statements that can be objectively proven true or false based on observable data (e.g., “The Earth is round”).

  • Opinions: Subjective beliefs or preferences that cannot be objectively verified (e.g., “This is the best ice cream”).

However, in real life, the line between fact and opinion often blurs. Even in hard sciences, facts can depend on definitions — and definitions are, ultimately, subjective.

Example: How many planets are in the solar system?

Pluto used to be the ninth planet. But discoveries of similar-sized objects like Eris, Haumea, and Makemake challenged this. If Pluto is a planet, why not the others? If not, why not revise the whole definition?

In 2006, the IAU defined planets more strictly and reclassified Pluto as a “dwarf planet.” Yet even today, the definition remains controversial. This shows how:

Facts must be expressed in language, and language involves definitions — which are subjective. Therefore, defining key terms clearly is vital in critical thinking and debate.

7. Steps in Critical Thinking

The book explains how critical thinking applies across different contexts: reading, writing, analyzing arguments, constructing arguments. These can be synthesized into a general process:

  1. Understand the problem: What is being asked? What’s the context?

  2. Redefine the problem if needed: Seek the root cause or the original need.

  3. Define key terms: Clarify ambiguous or multi-meaning words that could cause confusion.

  4. Gather data and information:

    • Distinguish primary sources (original documents, raw data) from secondary sources (interpretations, summaries).

    • Question whether information providers are open to scrutiny.

  5. Analyze the data:

    • How many variables or parameters affect the model?

    • Use visuals: mind maps, flowcharts, tree diagrams, etc.

    • Use dump lists: filter, sort, simplify.

  6. Evaluate assumptions and beliefs:

    • Identify and weigh facts vs. opinions.

    • Break arguments into premises and conclusions.

    • Use logical connectors (e.g., “however,” “therefore”).

  7. Use sound reasoning:

    • Deductive: From general to specific (e.g., “All men are mortal. Socrates is a man. Therefore, Socrates is mortal.”).

    • Inductive: From specific to general (e.g., “All swans I’ve seen are white. Therefore, all swans are white.” — which can be disproven).

    • Find implicit assumptions behind arguments.

  8. Follow logical patterns:

    • Syllogisms (major premise, minor premise, conclusion).

    • Avoid common fallacies (see Section 8).

  9. Triangulate (“compare from three angles”):

    • Multiple sources for data.

    • Multiple methods for collecting the same data.

    • Multiple observers interpreting the evidence.

    • Multiple contexts to test consistency.

    • Multiple theories for interpreting the same data.

Finally, ask:

  • Does this align with common sense?

  • Who is making the claim, and do they have a bias?

  • Are they using data honestly?

  • Is this idea too broad or too narrow?

  • Are you letting others’ emotions sway your thinking?

Critical thinking is multi-step, rule-heavy, demanding both rigorous analysis and creative insight. At its core, it’s neutral, nonpartisan reasoning — like a debate judge — weighing all sides before giving a tentative conclusion that remains open to revision with new evidence.

The author applies this to topics like climate change, criticizing how “global warming” was rebranded as “climate change” to shut down debate. He also compares it to COVID-19 vaccine safety, implying similar issues of political pressure and suppression of dissenting views.

8. Common Thinking Fallacies

Knowing the mistakes in reasoning is as important as knowing the correct ways to think. The book lists common logical fallacies, many of which also appear on Wikipedia’s massive list. Some highlighted examples:

  • Non sequitur (“It does not follow”): The conclusion does not logically follow from the premises.
    Example: “Wedding rings are bad because they originated as a symbol of women’s submission.” — The conclusion doesn’t logically follow from the origin.

  • Affirming the consequent:
    If P then Q.
    Q is observed.
    Therefore, P.
    Example: “If there’s a fire, there will be smoke. There is smoke, so there must be a fire.” — But smoke can come from many sources.

  • Straw man: Misrepresenting or exaggerating someone’s argument to make it easier to attack.

  • Correlation ≠ Causation:
    Just because A and B occur together doesn’t mean one causes the other.
    Classic example: Roosters crow at sunrise; therefore, crowing causes sunrise.

  • Circular reasoning: The conclusion is used to support itself.

  • False dichotomy: Presenting only two options when more exist.
    Example: “We must choose between Chinese and American education models.” — Why not combine their best aspects?

  • Redefinition (semantic games): Changing the meaning of terms to suit your argument.
    Example: Calling CO₂ “the primary greenhouse gas” when in fact, water vapor accounts for 80% of the greenhouse effect.

  • Double standards: Holding others to rules you don’t follow yourself.

  • Ambiguity: Using vague language to dodge questions or change the subject.
    Example: Clinton claimed he used force against bin Laden, but in reality, gave orders not to kill him unless necessary.

  • Wishful thinking: Believing something is true because you want it to be.

  • Appeal to ignorance:
    “You can’t prove X is false, so X must be true,” or vice versa.
    Example: “There’s no evidence God exists, so He doesn’t exist.” — A logical error; lack of evidence isn’t evidence of absence.

9. Other Persuasion Techniques

In real life, logical reasoning alone rarely persuades people. Emotion, interests, and psychological triggers matter. The book outlines rhetorical techniques used in debates and persuasion:

  • Appeal to emotions like hope, fear, or desire.

  • Use catchy slogans.

  • Exploit ignorance: Admit you don’t know to gain sympathy, or claim no one knows the answer.

  • Use jargon to seem knowledgeable and obscure your logic.

  • Deflect with questions:
    Example:
    Q: “Why did you do that?”
    A: “Why shouldn’t I?”

  • Ad hominem attacks: When logic fails, attack the opponent’s character, motives, or background. While often frowned upon, it can sometimes be effective — and revealing.

These tools, like knives or fire, are neutral — their morality depends on the user and the goal.

10. Real-World Applications of Critical Thinking

The author analyzes some of the most influential arguments in history using critical thinking.

(1) Rule by Elites (Plato’s Republic)

Argument: Smart, selfless elites should govern because the masses are incapable of knowing what’s best. Use propaganda to keep people satisfied.

Flaws:

  • Power corrupts even the most well-meaning elites.

  • History shows the ruling class can be selfish and manipulative.

  • People need more than comforting lies; conflict is part of human nature.

  • It’s elitist and dismissive to say ordinary people can’t contribute to society’s decisions.

  • Propaganda to pacify the public undermines truth and democracy.

(2) Rule by the Masses (Marx and Engels)

Argument: The working class should overthrow elites and abolish class divisions.

Flaws:

  • In practice, this created new elites (party bureaucrats) who also exploited people.

  • Classlessness proved hard to maintain; power structures always re-emerged.

(3) Hitler’s Racial Superiority Argument

Argument: Racial mixing dilutes superior genes. The strong must not breed with the weak, or greatness is lost.

Flaws (summarized with ChatGPT help):

  • Distorts Darwinism — evolution is not about racial purity.

  • The concept of “racial purity” is scientifically discredited.

  • Promotes immoral ideas of dominance and suppression.

  • Misuses “survival of the fittest” as a moral claim, when it’s just a descriptive principle.

(4) God Exists (Anselm’s Ontological Argument)

Argument: God is defined as the greatest being imaginable. A being that exists is greater than one that doesn’t. Therefore, God must exist.

Flaws:

  • You could use the same logic to “prove” anything exists — just define it that way.

  • Assumes everyone accepts the same definition of God.

  • Compares God to physical objects (like a house), which is a flawed analogy.

  • It’s a non sequitur — the conclusion doesn’t follow logically.

(5) God Doesn’t Exist (The Problem of Evil)

Argument: If an all-good, all-powerful God existed, the world wouldn’t be full of suffering. But it is — therefore, God doesn’t exist.

Flaws (via ChatGPT):

  • Assumes a perfect world is the only acceptable outcome.

  • Ignores concepts like free will or spiritual growth through suffering.

  • Commits the appeal to ignorance fallacy — lack of proof ≠ disproof.

(6) Neuron Count in the Brain

Example from the author: The accepted “scientific fact” for decades was that the brain has 100 billion neurons. Neuroscientist Suzana Herculano-Hou questioned this, found no real evidence, and created a new counting method. Her result: 86 billion neurons. She also showed brain cell density, not just size, explains intelligence differences among species. Her TED talk, What Makes the Human Brain Unique, is worth watching.

This shows: Science progresses through critical thinking, challenging assumptions, and verifying data.

11. Conclusion

Reading this “For Dummies” book was tough but rewarding. Key takeaways:

  • Natural thinking has its uses and shouldn’t be entirely rejected.

  • A true critical thinker accepts: Everything I believe could be wrong. If needed, I must rebuild my reasoning from scratch.

  • Critical thinking involves balanced reasoning, like a debate judge: gather evidence from all sides, weigh it fairly, and reach a provisional conclusion, open to future revision.

  • Humanity’s deepest flaw is tribalism and identity politics — judging and mistreating entire groups based on race or identity instead of individual actions.

  • Critical thinking is key to innovation and scientific discovery, especially when hidden assumptions are questioned and verified.

Finally, I have found that ChatGPT can now provide pretty good critical analyses of historical arguments — sometimes even surpassing my own. But its performance on real-time, complex controversies (e.g., COVID vaccines, war narratives) remains to be fully tested.

Original Chinese version: https://mp.weixin.qq.com/s/kUr2jwbTCOzzm0cXi-1BXw