Why Smart People Believe Dumb Things: 35 Fallacies and Cognitive Biases That Shape Our Thinking

Introduction

Ever wondered why a well-educated, rational person sometimes makes the most illogical and baffling decisions? Why, despite being smart, do they fall into conspiracy theories and bad investments? The answer lies in some hidden glitches of the mind. They take shortcuts, rely on habits, and are constantly influenced by emotions, culture, and beliefs. These shortcuts are known as cognitive biases, and the common errors in reasoning are called logical fallacies, both of which can trick even the smartest brains into believing senseless and irrational ideas and concepts. In this post, we discuss the 35 most common fallacies and biases that shape how we think, decide, and sometimes misjudge the world around us.

Logical Fallacies (Errors in Reasoning)

1. Ad Hominem Fallacy- This is the error of attacking the person arguing instead of the argument itself. The fallacy includes the attempt to refute or win an argument by diminishing the intelligence, morals, education, and qualifications of the person in opposition. The major difficulty of identifying an Ad Hominem is to understand whether the personal attack is relevant or not. This fallacy is used by dictators and authoritarians to disintegrate the value of intelligence and motive of the opposing group.
2. Strawman Fallacy- It is the act of misrepresenting someone’s argument to make it easier to attack. In a Strawman, the person making the argument turns the arguments of their opponent into a laughable parody, thus winning the argument without refuting or even challenging the actual argument. This is a dangerous tool that is used in media, politics, and even domestic arguments.
3. False Dilemma- This fallacy happens when only two options or solutions are presented when more exist. It mainly happens like this, “……you either have to choose this or that.” Also known as a false dichotomy, where the opponent is led to a dichotomy of choice or preference despite having many more easier choices.
4. Slippery Slope- It is the argument to claim that one small step will lead to an outstanding outcome. It is rarely included as a logical fallacy because the outcome is mostly action-based. But still, it is very common and is often seen among people who claim extraordinary achievements can be achieved through ordinary efforts and resources.
5. Circular Reasoning- It is the fallacy of using a conclusion as part of the argument’s premise. It is an argument where A is because of B, and B is because of A. It is also the act of repeating the same argument in different ways by concluding from different directions. This fallacy is very common in people who have a strong tendency to lie in every situation.
6. Hasty Generalization- It happens when a conclusion is drawn from limited data. In a hasty generalization, the error is in jumping to an outcome without clearly analyzing and interpreting a sizable amount of data to achieve a logical outcome.
7. Post Hoc Ergo Propter Hoc- It is the act of assuming that because one event followed another, the latter is likely to be the cause of the former. Here, if the event A is followed by the event B, the person making the fallacy argues that A is likely to be the cause of B.
8. Appeal to Authority- It is the fallacy of believing something is true because an authority says so. Here, the person, in order to win an argument, proclaims that his reasoning is true because it is backed up by some sources of higher authorities, which may or may not know about the topic in question itself. It is a very common fallacy that is commonly seen in political debates and even in academic arguments.
9. Appeal to Emotion- When a person tries to win an argument by manipulating emotions instead of logical reasoning, the act is known as Appeal to Emotion. Commonly seen in orthodox religious arguments, the debater makes a mistake of using emotion as the primary tool instead of logic or reasoning in an argument. It is also used as a popular weapon by people who specialize in playing the victim in every situation.
10. Bandwagon Fallacy- It is believing something is true because many people believe it. The person argues that the event or the thing is real, ethical, or logical, as most people follow it. Here, the person making the fallacy joins the bandwagon of the contemporary practice and defends it without presenting any logical argument in favor of it. Most common among normal citizens in political arguments, where they just use the fallacy to defend their political ideology, as their friends and families follow it, without themselves doing their own logic and reasoning.
11. Red Herring- It is the art of diverting attention from the topic of argument to an irrelevant topic. Red Herring is a smelly fish whose odor can distract even a bloodhound. So the fallacy is named after the fish, as it is used as a method of distraction when unable to present logic, season, fact, or evidence.
12. No True Scotsman- In this fallacy, the person making a mistake redefines terms in order to protect a generalization. It is a kind of rescue act in which the person reinterprets the event or term in question to escape a refutation of the generalization.
13. Tu Queue- This mistake occurs when one dismisses criticism by pointing out hypocrisy. It is the act of denying some act as faulty because the opposition has also performed it. It generally involves the phrase, “Preach what you practice,” as a defense mechanism against the argument. The opposition may be hypocritical, but that does not degrade the values of their arguments.
14. False Equivalence- It is a common fallacy where two different and unlike things are treated as if they are the same. Here, the person evaluates two completely different events, things, or ideas as the ‘different sides of the same coin,’ thereby dismissing the opponent’s argument without using any proper logic or reasoning as a tool.
15. Begging the Question- It is the act of assuming the opponents’ arguments and intentions even before they are presented. Related to Circular Reasoning, it is a form of dismissing or at least delaying the debate by creating an assumed reason and logic of the opponent. It often leads to a delay of the discussion, with it rarely coming to a definite, logical, and reasonable conclusion.

Cognitive Biases (Mental Shortcuts That Distort Thinking)

1. Confirmation Bias- It is the tendency to seek information that supports existing beliefs. Confirmation Bias often happens when we want certain ideas to be true. It results in dismissing facts, arguments, and ideas that go against the common belief. Here, people generally pick and choose information that goes along with their idea or agenda.
2. Anchoring Bias- This bias happens when we rely on or anchor to the first piece of information to achieve a certain conclusion. As the process continues and new information is gathered, we try to interpret the newer information based on the information we anchored earlier. This results in a skewed or biased conclusion, which heavily depends on the initial information.
3. Availability Heuristics- It is the bias of overestimating the importance of easily recalled examples. It results from overdependence on the most readily available data. It can also be seen when diagnosing health symptoms using artificial intelligence, where the horrible results are shown mostly because they can be easily recalled.
4. Dunning-Kruger Effect- It is the typical symptom in which the less someone knows, the more confident they are. Though rarely classified as a cognitive bias, this leads to people overestimating their level of competence in an area where, in reality, they sometimes can have competence of next to none.
5. Survivorship Bias- It is the bias of focusing on one’s successes while ignoring all the failures. It is a shortcut where the success of a subgroup within a larger group completely masks the failure of the entire group. The bias results in the negligence of failures, which could have been corrected in the beginning, but slowly and steadily, this eventually leads to the downfall of the project or the group.
6. Negativity Bias- It is the bias of giving more weight to negative experiences. It generally happens when there is already a collection of positive experiences of the same magnitude, but we only focus on the negative experiences while making any decision. This is one of the most common biases that can be seen in everyday life.
7. Self-Serving Bias- It is the bias in which we give the reason for success to ourselves while blaming the reason for failures on external factors. This is common in most of us, as our natural tendency is to praise our talents and skills and blame our losses to bad luck or influences by others.
8. Sunk Cost Fallacy- It happens when someone continues a behavior or investment (time, money, or effort) because they have already spent resources on it, even if continuing is irrational or even harmful. It is considered a bias and not a fallacy because it is a mental shortcut that leads one to make decisions based on past investment rather than current or future benefits, similar to other biases.
9. Halo Effect- It is the tendency to let one positive trait influence perception over other traits. For example, in movies, we generally have an attractive lead, which feeds our assumption that an attractive individual should be good at heart. Many of us assume a not-so-good-looking person to be unfit for playing the lead role in an event.
10. Ingroup Bias- This is a bias in which we favor people who belong to our own group. It is a type of favoritism that leads us to silly decisions like giving responsibility to an unqualified person only because we fall in the same group, like having the same mother tongue or following the same sports team. We connect to even small similarities, and that clouds our decision-making capabilities because of the Ingroup Bias.
11. Optimism Bias- It is the tendency to engage in wishful thinking and believe that nothing wrong will happen, even though there are possibilities of negative outcomes. This can lead to poor decision-making without a proper backup if certain unwanted outcomes arise.
12. Overconfidence Bias- It is the act of overestimating one’s own knowledge or ability. This blurs ones judgement of themselves with respect to various capabilities in different fields.
13. Status Quo Bias- This tendency leads to a preference for things to remain the same forever. This bias stops people from changing their present status, whether in their personal lives, publicly, or at professional levels. This is seen in many older people, who refuse to change according to the evolution of society, as they prefer to live according to the time of their youth, which has probably passed decades earlier.
14. Framing Effect- It is the bias of reacting under the influence of how the information is presented to us. The same information can be interpreted in a different way depending on how it is presented. A classic example is whether a glass of water is presented as half-filled or half-empty.
15. Recency Bias- It is the act of giving more importance to recent events. Sometimes, while making a decision, we only give importance to the recent past and totally neglect the age-old history. This results in some form of silly decisions, which may fail heavily in the far future.
16. Hindsight Bias- It is the tendency of believing the past events were predictable after they actually happened. After knowing the outcomes, our thinking gets blurred by the idea that the past events were predictable, as we can now see the causes after the effects had already happened.
17.  Fundamental Attribution Error- It is the tendency to overestimate personal traits and underestimate situations in judging others. In other words,s we believe that personal traits are more important than various situations in determining outcomes. Examples of this include if A and B are at the same distance from point O and if A reaches O earlier than B, we assume A is faster, totally neglecting the transportation cost, terrain, and traffic.
18. Illusory Correlation- It is the tendency to see connections between two events, although none exist in reality. It is closely linked to memory and perception, as people can find patterns within various events in their memory that were totally unrelated.
19. Authority Bias- It is the tendency to trust an authority, although they might be wrong. This further leads to Appeal to Authority, which was discussed earlier. Certain examples include trusting a doctor in medical diagnosis and a lawyer in legal matters blindly without a second opinion, although both of them might be wrong.
20. Cognitive Dissonance- It is the discomfort from holding conflicting beliefs or behaviors. It is a psychological discomfort that we try to reduce by ignoring that both the beliefs contradict and oppose each other. In order to find resemblance in two conflicting views, we tend to distort their true meaning according to our liking.

Conclusion

Our minds are powerful, but they are not perfect. Fallacies and biases are invisible strings that tug at our logic, nudging us toward choices that feel right that aren’t always true. The more we learn to spot them in our thoughts, debates, and everyday decisions, the freer we become from those mental traps. True intelligence isn’t about never being wrong; it’s about knowing when our brain is fooling us and daring to question it. That’s all for today. Please like, comment, share, and subscribe if you find this blog helpful. Thank you.

Suggested Readings

• Internet Encyclopedia of Philosophy
• Logical-Fallacy.com
• The Decision Lab
• The Catalogues of Bias
• Thinking, Fast and Slow by Daniel Kahneman

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