What's So Critical About Critical Thinking?

Imagine you're at the local basketball court when a stranger named Bob challenges you to a game. "Sure!", you say, as you notice a crowd gathering to watch. You make the first basket, but Bob says, "That didn't go in." Then he shoves you, grabs the ball, shoots, and misses. The crowd cheers, "Whoo! Great shot, Bob!" You keep making baskets, but Bob refuses to acknowledge them and misses all his own shots. Finally, the crowd declares him the winner.

Most people wouldn't dream of playing basketball under these conditions, but many us do get into public debates on social media, and that can be a pretty similar experience. Have you ever tried to reason with someone who thinks personal attacks and ALL CAPS make devastating arguments, in front of an audience who thinks so too? I know I have. Social media has revealed that our country is full of people who don't know the basic rules of logic and evidence. While most people do know that games like basketball have to be played according to rules to avoid chaos, many don't know that the same applies to reasoning and debate.

That's a big problem, because democracies depend on citizens being able to have reasonable, logical discussions. And that requires that people be able to think clearly and logically. Good debate and good thinking are closely related, because in both cases, conclusions need to be based on logic and evidence.  This means the poor quality of public debate in our country reflects a deeper problem: a widespread lack of critical thinking ability in its citizens. It's not all citizens, of course, but it's far too many.

So what's the the solution? Here's a suggestion from one of the founders of our democracy, Thomas Jefferson:

I know no safe depository of the ultimate powers of the society, but the people themselves: and if we think them not enlightened enough to exercise their control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education. 

"Inform their discretion by education." This mirrors Margaret Mead's dictum that people should "be taught how to think, not what to think." Education is where schools come in, but it's also where public libraries come in, because one of our reasons for our existence is making sure people of all ages have the tools they need to be thoughtful, informed citizens.

Defining Terms: What is Critical Thinking?

DPL has many great resources on critical thinking, but first it might help to say what critical thinking actually is, because it's become one of those fashionable phrases that's thrown around more than defined. First, the word "critical" doesn't mean "negative", but something more like "evaluative". To think critically is to evaluate beliefs, claims and decisions carefully, to make sure they're supported by logic and evidence. And here's the hard part: it's not just evaluating other people's beliefs and decisions, but your own as well. As the physicist Richard Feynman said, "The first principle is that you must not fool yourself – and you are the easiest person to fool."

The psychologist Edward Glaser defined critical thinking in terms of three traits: 1. An "attitude of being disposed" to think critically. 2. "Knowledge of the methods of logical inquiry and reasoning". 3. "Some skill in applying those methods."

Notice that the first thing he mentioned isn't knowledge, but attitude. Critical thinking requires that you care whether your thinking is reasonable, and whether your beliefs are true. It's no good knowing the principles of logic and evidence if you aren't committed to using them to seek the truth. Someone who knows all the principles of reasoning, but can't be bothered to use them--or worse, uses them in dishonest ways--isn't a good critical thinker.

Similarly, someone who knows the rules of logic, but doesn't have any skill in applying them (Glaser's third trait), isn't a good critical thinker either. Like most stills, critical thinking takes practice and dedication as well as knowledge. It's like chess: the basic rules are simple enough, but it takes years to master the game.

Cognitive Biases and Logical Fallacies: The Enemies of Reason

Many people assume that good thinking is something that comes naturally, but psychologists, logicians, and a brief glance at a YouTube comment section say otherwise. The path to good reasoning is full of pitfalls. For one thing, our minds can play tricks on us. Here's an example: If you click on the second image in this blog, it's obvious that the table on the left is longer than the one on the right. Except it isn't. The top surface of both tables are exactly the same shape and size, just rotated (get out a ruler if you want proof--I did). It's a powerful optical illusion that tricks our brains into thinking one table is longer and thinner than the other, and it's just one of dozens of illusions that keep us all from seeing the world as it really is.

Psychologists have also identified many cognitive biases, which are basically optical illusions of reasoning. One of the best-known is confirmation bias, which causes us to seek out confirming evidence for things we want to believe, while ignoring evidence for things we don't. Confirmation bias is one of the main causes of the fake news phenomenon in recent years, and we talk about it in our fake news programs here at DPL. Another bias that makes people fall for fake news is in-group bias, which makes us quick to find fault with people outside our group or political tribe, while ignoring faults within our own group. There's also the bias of illusory superiority, sometimes called the Lake Wobegon effect, which causes the average person to think they're smarter and better-looking than the average person. These are just three examples of the multitude of psychological biases we're all prone to.

Most of us are also guilty of committing logical fallacies from time to time. One fallacy that's always popular on social media and talk radio is the ad hominem fallacy (Latin for "to the person"), where people focus on personal characteristics of the person making the argument, rather than the logic of the argument itself. Another fallacy that's popular these days is the tu quoque (you too) fallacy, which is sometimes called whataboutism: (Your party has politicians who lie, therefore it's OK if ours do). As with cognitive biases, there are multitudes of logical fallacies lying in wait for us, ready to make us less reasonable than we should be.

Arguments: Good, Bad, and Missing

What most logical fallacies and cognitive biases have in common is that they cause us to make bad arguments. As with the word "critical," the word "argument" has a particular meaning when applied to critical thinking. It doesn't necessarily mean "disagreement". In logic, an argument is a claim or conclusion supported by premises. In other words, an argument is a claim combined with some reasons for accepting the claim. If I say, "I think smoked meat is bad for you, because studies show it's carcinogenic", I've made an argument. There's a claim ("smoked meat is bad for you") as well as a reason, or premise, supporting it ("there have been studies").

In more formal logical, you usually see the premises stated before the conclusion, as below:

     Premise: All ostriches are birds.

     Premise: Fred is an ostrich.

     Conclusion: Therefore Fred is a bird.

But in ordinary language, premises often come after the conclusion, or may even be unstated. For example, if I say, "Fred is a bird, because he's an ostrich", I've put the premise after the conclusion, and left out the premise "All ostriches are birds", because it's assumed that most people know that. 

What's interesting about many debates is that they're full of people making claims without actually making arguments, because they don't include any supporting premises. How often do people say things like, "Senator Smithers is a criminal!!" or "You're an idiot, LOL!", without giving any reasons to support that claim? If you look at the average Facebook argument, you'll notice that naked claims without supporting reasons are almost as common as logical fallacies and cognitive biases.

Equally common are bad arguments--arguments where the premises don't actually support the conclusion. For an argument to be good, the premises need to be true AND the conclusion has to follow from the premises. If I state the premise "Platypuses lay eggs", and conclude "Therefore they are birds", the premise is true, but the conclusion doesn't follow from it. If I say "Platypuses have four legs, so they are mammals", the premise and the conclusion are both true, but it's still a bad argument, because the conclusion doesn't necessarily follow from the premise (many animals with four legs aren't mammals). Finally, if I say, "Platypuses don't lay eggs, therefore they are mammals", then the conclusion is true, but the premise is false. 

You may notice that there are more ways for an argument to be bad than good. And arguments can get much more complicated than these simple examples, with simple arguments building on each other to form complex chains of argument. There are also different kinds of arguments, including various kinds of deductive arguments, which are common in math and formal logic, as well as inductive arguments, which are common in science (science literacy is closely related to critical thinking, because both require basing conclusions on evidence). We could get into the details of the various kinds of reasoning, but this post is long enough, and I would rather refer you to people who know more about this than I do. Here are some great resources for about cognitive biases, logical fallacies, and critical thinking. 

Got questions? Ask Us or call Reference Services at 720-865-1363! 

Cognitive Biases

You Are Not So Smart / David McRaney. A witty guide to the most common ways our own minds can fool us.

You Are Now Less Dumb / David McRaney. Further explorations in cognitive biases, and how to overcome them.

Thinking, Fast and Slow / Daniel Kahneman. A summary of the life's work of one of the founding researchers in cognitive biases.

Your Bias Is. An online, visual guide to common cognitive biases. Available as a poster.

Logical Fallacies

Mastering Logical Fallacies : The Definitive Guide to Flawless Rhetoric and Bulletproof Logic / Michael Withey. An introduction to the most common logical fallacies.

With Good Reason: An Introduction to Informal Fallacies / S. Morris Engel

Rhetological Fallacies. A nice online infographic from the website Information is Beautiful

Your Logical Fallacy Is. A online, visual guide to common logical fallacies. Also available as a poster.

Critical Thinking and Logic

A Field Guide to Lies: Critical Thinking in the Information Age / Daniel Levitan. An up-to-date book on how critical thinking is vital in the age of online misinformation.

Your Deceptive Mind: A Scientific Guide to Critical Thinking Skills / Steven Novella. A video series from The Great Courses about science and critical thinking.

An Introduction to Formal Logic / The Great Courses. This is a video lecture series on our new streaming video service, Kanopy. While later lectures get quite technical, the first 8 focus on the basics of informal reasoning and critical thinking.

Why People Believe Weird Things: Pseudoscience, Superstition, and other Confusions of our Time. A book about the difference between science and pseudoscience, by a leading science advocate.

Influence : Science and Practice / Robert Cialdini. This is not a book about critical thinking per se, but a book about powerful tricks advertisers, politicians, salespeople, and cult leaders use to convince us to do what they want. 

Going Deeper with Prospector

Critical thinking is often taught as a course in high school and college, and there are some excellent and readable textbooks out there. Public libraries don't usually collect textbooks (for various reasons) but many of these textbooks are available through Prospector if you search for "critical thinking" or "reasoning".

Written by Ross on June 29, 2018


Average Joe on July 1, 2018


Thanks for this great post. I'm looking forward to reading Mastering Logical Fallacies!

What on July 11, 2018


Me no know

Anonymous on July 26, 2018


Critical thinking skills are important and extremely useful for our daily lives.

Allan Brooks on July 26, 2018


Positive atmosphere and motivation from parents will help the child in developing critical thinking skills. I personally know Eye Level Bolingbrook. Their staff goes through continuous educational training that ensures standardization and emphasis is on proactive and lifelong learning.

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