9 Logical Fallacies That You Need to Know To Master Critical Thinking

William James, who was known as the grandfather of psychology, once said: “A great many people think they are thinking when they are merely rearranging their prejudices.” All of us think, every day. But there’s a difference between thinking for thinking’s sake, and thinking in a critical way. Deliberate, controlled, and reasonable thinking is rare.

There are multiple factors that are impairing people’s ability to think critically, from technology to changes in education. Some experts have speculated we’re approaching a crisis of critical thinking, with many students graduating “without the ability to construct a cohesive argument or identify a logical fallacy.”

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That's a worrying trend, as critical thinking isn’t only an academic skill, but essential to living a high-functioning life. It’s the process by which to arrive at logical conclusions. And in through that process, logical fallacies are a significant hazard.

This article will explore logical fallacies in order to equip you with the knowledge on how to think in skillful ways, for the biggest benefits. As a result, you'll be able to detect deception of flawed logic, in others, and yourself. And you'll be equipped to think proper thoughts, rather than simply rearrange prejudices.

What Is a Logical Fallacy?

The study of logic originates back to the Greek philosopher Aristotle (384–322 b.c.e), who started to systematically identify and list logical fallacies. The origin of logic is linked to the Greek logos, which translates to language, reason, or discourse. Logical fallacies are errors of reason that invalidate an argument. The use of logical fallacies changes depending on a person’s intention. Although for many, they’re unintentional, others may deliberately use logical fallacies as a type of manipulative behavior.

Detecting logical fallacies is crucial to improve your level of critical thinking, to avoid deceit, and to spot poor reasoning; within yourself and others. The influential German philosopher Immanuel Kant once said; “All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.”

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Throughout history, the world’s greatest thinkers have promoted the value of reasoning. Away from academia, reason is the ability to logically process information, and arrive at an accurate conclusion, in the quest for truth. Striving to be more reasonable or calm under pressure is a virtuous act. It’s a noble pursuit, one which in its nature will inspire your personal development, and allow you to become the best version of yourself.

Why Critical Thinking Is Important

It seems like humanity has never been so polarized, separated into different camps and stances; Democrats vs. Liberals, vegans vs. meat eaters, vaccinated vs. unvaccinated, pro-life vs. pro-choice. There’s nothing inherently wrong with thinking critically, and taking a stand. However, what is unusual is the tendency for people to lean into one extreme or the other, neglecting to explore gray areas or complexity.

Many of the positions people take are chosen for them. It takes a lot of effort to research a point of view. And even then, we’re faced with the challenge of information overload, fake news, conspiracy, and even credible news which is dismissed as conspiracy. Far from academic debates or politicians facing off during leadership races, the ability to share respectful dialogue is an essential part of understanding our place in the world, and maintaining human relationships.

The hot topics facing humanity aren’t going to be resolved by reactivity or over-emotionality. There should be room for all sorts of emotions to surface; it’s understandable to feel anger, grief, anxiety, etc, faced with global events. But critical thinking asks for a more reasoned, calm consideration, not getting completely carried away with emotions, but appealing to higher judgment.

Examples of When to Use Critical Thinking

It’s not always clear why critical thinking is so valuable. Isn’t it only useful for education, philosophy, science, or politics? Not quite. When applied appropriately, logic has a universal appeal in life. Examples include:

• Problem-solving: “The problem is not that there are problems,” wrote psychiatrist Theodore Isaac Rubin, “the problem is expecting otherwise, and thinking that having problems is a problem.” Life is full of problems. Fortunately, that means life is full of opportunities to problem solve. Critical thinking is an essential problem-solving skill, from managing your time to organizing your finances.
• Making optimal decisions: the more logical you are, and the less you fall into logical fallacies, the better your decision-making becomes. Decisions are the steps towards your goals, each decision making you closer to, or away from, what you really desire.
• Understanding complex subjects: with attention spans reducing due to social media and technology, it’s becoming rare to take time to attempt to understand complex topics, away from repeating what others have said. Whether through self-study or to comprehend global events, critical thinking is essential to understand complexity.
• Improving relationships: adding a dose of logic to your interactions will allow you to make better choices in relationships. Many “messy” forms of communication, from guilt-tripping to passive aggression, are illogical. By tapping into a more balanced point of view, you’ll better overcome conflict, argue your point (when necessary), or explain the way you feel.

The Most Common Logical Fallacies

When you begin to explore logical fallacies, language becomes a game. There’s a sense of having a cheat sheet in communication, understanding the underlying dynamics at play. Of course, it’s not as straightforward as a mechanical understanding — emotional intelligence, and non-verbal body language has a role to play, too. We’re humans, not computers. But gaining mastery of logic puts you ahead of the majority of people, and helps you avoid cognitive bias.

What’s more, most people fall into logical fallacies without being aware. Once you can detect these mechanisms, within yourself and with others, you’ll have an upper hand in many key areas of life, not least in a professional setting, or in any place you need to persuade or argue a point. The list is ever-growing and vast, but below are the most common logical fallacies to get the ball rolling:

1. Ad Hominem

Originating from a Latin phrase meaning “to the person,” ad hominem is an attack on the person, not the argument. This has a twofold impact — it deflects attention away from the validity of the argument, and second, it can provoke the person to enter a defensive mindset. If you’re aware of this fallacy, it can keep you from taking the bait, and instead keeping the focus on the argument.

Perhaps the most popular example of this in recent times is the viral interview between Jordan Peterson and Cathy Newman. Love him or hate him, Peterson is an embodiment of logic, sidestepping Newman’s ad hominem attacks and fallacies in a calm and controlled manner. 

2. Red Herring

You might have heard of this phrase in the context of fiction: a red herring is an irrelevant piece of information thrown into the mix, in order to distract from other relevant details, commonly used in detective stories. In a political context, you might see a politician respond to criticism by talking about something positive they’ve done. For example, when asked why unemployment is so high, they may say “we’ve made a lot of effort to improve working conditions in certain areas.”

A popular type of red herring in modern discourse is "what aboutism," a form of counter-accusation. If the person mentioning unemployment is a fellow politician, the same politician may say: “what about unemployment rates when your party was in charge?”

3. Tu Quoque Fallacy

Closely related to the above, and in some ways, a mixture of the ad hominem and a red herring, is the tu quoque fallacy (pronounced tu-KWO-kway and originating from the Latin “you too”). This is a counter-accusation that accuses someone of hypocrisy. Rather than acknowledging what's been said, someone responds with a direct allegation. For example, if you’re in an argument and your partner raises their voice, you may bring that to their attention, only for them to say: “you raise your voice all the time!”.

4. Straw Man

The straw man logical fallacy is everywhere, especially in dialogue on hot-topic issues, because it's effective in shutting down someone else’s perspective. The person runs with someone’s point, exaggerates it, then attacks the exaggerated version — the straw man — seemingly in an appropriate way. For example, when your partner asks if you could do the washing up, you might respond: “are you saying I don’t support you around the house? That’s unfair.”

On the global stage, one of the big straw man arguments in recent times is the rhetoric of the anti-vaxxer, applied to resistance to mandated vaccines, social distancing, or lockdowns. The simplified term is a way of positioning someone as extreme, even if raising valid points, or looking to open dialogue about the repercussions of certain political choices, made without the option for the population to have their say.

5. Appeal to Authority

If someone in a position of authority says something is true, it must be true. This type of logical fallacy is ingrained in the psyche in childhood, where your parents' (or adults around you) word was final. Society is moving increasingly in this direction, especially in the fields of science. But that doesn’t come without risk, as even experts are known not to get things right. 

In addition, many positions of authority aren’t always acting in pursuit of honesty or truth, if other factors (such as financial donations) have influence. While appeals to authority used to gravitate around religious leaders, a 2022 study found that, when linked with scientists, untrue statements are more likely to be believed, in what researchers call the Einstein effect.

6. False Dichotomy

Also known as the false dilemma, this logical fallacy presents limited options in certain scenarios in a way that is inaccurate. It’s closely linked to black-or-white thinking or all-or-nothing thinking, presenting two extremes without options in between. This is perhaps one of the most invasive logical fallacies in navigating life’s demands. For example, you either go to the gym or become unhealthy.

These limitations require a dose of psychological flexibility and creative thinking to overcome. They require exploring other alternatives. In the example above, that would mean looking at other ways to become healthy and exercise, such as running outdoors or going swimming.

7. Slippery Slope Fallacy

Similar to the straw man fallacy, the slippery slope is a way of taking an issue to a hypothetical extreme and then dismissing it based on what could happen. The potential of one thing leading to another, and the repercussions of that chain of events, may cause the original issue to be overlooked. For example, if you fail to set a boundary in one situation, you’ll forever be stuck in accepting certain behaviors.

The issue with this fallacy is that a valid process of critical thinking is to look at what decisions can lead to in the future. Rather than dismiss outright, however, it pays to make reasoned decisions, avoid jumping to conclusions, and see how things unfold over time.

8. Sunk Cost Fallacy

This is the logical fallacy that, when having already invested in something, you continue to invest in order to get return on your sunk costs. Although using gambling terminology (such as chasing losses on roulette) the sunk cost can apply to any area of life. The investment itself doesn’t have to be financial. For example, investing lots of time and energy into a creative project, or a relationship.

The sunk cost fallacy causes people to overlook a true and accurate analysis of the situation in the present moment, instead choosing to continue because of past decisions.

9. Hasty Generalisation

Also known as an over-generalization or faulty generalization, this logical fallacy makes general claims based on little evidence. Before writing this article, I went to a new gym, where my toiletry bag was stolen. You could argue it’s bad luck for something like that to happen on your first visit. If I decide that the gym isn’t safe, and make a hasty generalization, I may end up not going again. But what if the rate of theft in this gym was below the average in the city, and I was just unlucky? What if it wasn’t stolen, but someone absent-mindedly put it in their bag?

The opposite of a hasty generalization is to find the appropriate context for events. A logical conclusion, on the other hand, takes time. It’s reasonable, doesn’t jump in, and collects as much data as possible. If I go to the same gym, and something else is stolen, and I then see in Google reviews that others have had the same, it’d be logical for me to conclude there’s a high rate of theft.

How to Detect and Overcome Logical Fallacies

Both logic and critical thinking can be improved with practice. The knowledge of the nature of logical fallacies, and the above examples, will get you started. Deciphering when certain fallacies are active in real time is part of applied learning. Be conscious of applying the same level of rigor to your own level of reason as you do others.

There are a few components to detect and overcome logical fallacies. The first is self-awareness. As mentioned above, we’re humans, not machines. In situations where the stakes are high, we’re usually driven by factors other than logic, ulterior motives, or strong emotions that run the show. How often, when angry or triggered, do you say or act in ways you later regret?

Emotional regulation is useful in being calm enough to engage in critical thinking. But at times, logic isn’t the most skillful. For example, in conflict with a loved one, it’s more important to attempt to have compassion and understanding than to be the “most logical.” Sometimes, there are factors outside of reason that influence us, matters of the heart that can’t be captured, defined, or deconstructed by the mind.

Knowing how to apply logic, and when, is a vital skill. Through practice, over time, you’ll cultivate an even greater virtue — wisdom. A precious commodity in short supply, if you’re able to achieve wisdom and reason, the world is your oyster, a positive slippery slope to supercharge your growth.

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