Critical thinking

Critical thinking in education

Robert Ganley

Robert Ganley

Robert is a post-doctoral research assistant at the University of Zurich (UZH). He graduated with a PhD from the University of Glasgow in 2016, and also received a MRes with distinction from the same university. His current research interests include neuronal circuits for pain control and transmission in the central nervous system.

The access to information and the spread of ideas brought about by technological advancement represents a huge leap forward for humanity. However, with an increasing volume of communication present in everyday life there is a greater need to critically examine this overwhelming amount of information. Many of us are not educated in a way that allows such a critical appraisal of so many subjects. In this article I discuss the implications of a lack of critical thinking skills and why this should be an essential component of everyone’s education.

What is critical thinking?

Critical thinking is the systematic assessment of a system of beliefs. Although this is a broad and technical definition, it illustrates the scope of its application. Almost any claim, human endeavour, lifestyle choice, or belief system can be interrogated by critical thinking. The aim is simple; to determine the truth of a belief or claim using a logical and systematic approach. While the aim is simple, the application can be incredibly complicated. Everybody has their own pre-existing thoughts and ideas that are produced by our personalities and environment, with several influences coming from our society, culture, and our family and friends. On top of this, people are subjected to a constant stream of information, lots of which is heavily biased or misleading, with the intention of grabbing attention instead of informing. This can be entertaining but it is also a huge distraction from what is important and what is true.

Why is critical thinking important?

It is possible to find ‘evidence’ online to support almost anything believed by anyone. You can get information from media outlets, social media, or web forums, with widely varying and contradictory opinions and views. With all of this information out there, how do you decide what to believe? More importantly, what you believe and how you think will guide you through every decision you will ever make. Therefore, it is of great importance to have those beliefs formed reliably.

Furthermore, everything that is published or reported is biased in some way, because a person or a group of people with their own set of beliefs and opinions have created it. Inevitably these beliefs and opinions will impact on the tone of the article and which information is provided or excluded from it. Biased reporting therefore cannot be avoided, although there are attempts to provide a service that unbiases the news. This service aims to “fix the news”, since it recognises most news is biased by the reporting media group, and relies on readers to summarise news stories in an unbiased manner, as well as gathering the credible sources and tagging them with their bias (such as politically left or right wing). However, the content and arguments provided within articles can be directly critically assessed to see whether they make sense, are misleading, or have appropriate evidence to support their conclusions. When stripped of rhetoric, persuasive and emotional text, background information and repetition, many articles contain surprisingly little information. With this in mind, it becomes clear why critical thinking skills would be important, to be guided by the evidence and arguments in an article as opposed to the opinions of the authors.

More directly, we are all highly influenced by our friends, family and society, which in turn shapes our worldview. With the advent of social media this influence can be amplified, since the information you receive through social media is determined by you. It is simple to filter out anything that disagrees with your current worldview and focus on everything that confirms it. This can result in a reinforcement and amplification of an accepted set of views that remain unchallenged. This is thought to result in more polarized thinking and is the antithesis of critical thinking.

How does critical thinking affect our lives?

Who you choose to vote for is guided by your own experience, your own views, and also the information that you receive. Since you only occupy a small part of a big society, it is impossible to experience everything affecting all people at all times. As a result, you develop opinions about these subjects from the information you are receiving. The people you elect to run your country will by definition have a direct effect on your life and the lives of others. Therefore, to make the decision that is right for you and your ideals, it is important to have formed these opinions independently and reliably by critically analysing the information and your own experiences.

All scientific and technological advances required critical thinking. From forming a hypothesis, to testing a theory, all the way through to applying this knowledge to developing the technology that we enjoy today, every stage required thinking in a critical manner. The scientific method is based on critical thinking and shapes the scientific and technological advancements that have brought us to where we are today, and that will guide our future development: thus, it is essential that these skills are developed in more and more people. This could be introduced in all basic education to make this a reality.

The legal system of many countries relies on critical thinking to determine whether somebody has broken the law or is to be held accountable for something. This legal process requires inductive reasoning: in short, the establishment of facts and the most likely explanation for those established facts. The judge or jury then decide whether the accused is guilty of or is responsible for violating a law. Since the legal process is grounded in critical thinking, and the legal system is the foundation of law and order in a country, it follows that critical thinking is essential for that law and order. In countries that rely on trial by jury, such as the USA, UK and Australia, it would be highly desirable that each member of the jury was able to think critically. Juries consist of members of the general public, who come from all areas of society. In order to fairly determine the guilt or innocence of a fellow citizen everyone should receive basic training in thinking critically.

Critical thinking
Critical thinking. Cartoon @ Simon Kneebone for Culturico (copyright).

Consequences of not thinking critically

When ideas go unchallenged then the result is dogmatism. Dogmatism involves thinking or doing things in the same way without considering any other possibility. The result of such thinking invariably leads to stagnation in society without any progress or improvement, without which we wouldn’t have modern healthcare, education, or indeed functioning democratic societies. This lack of advancement would be a huge hindrance to solving many of the existential problems that we face today such as climate change, natural disasters and food shortages.

Hasty generalisations (also see below) are assuming the characteristics of something, or someone, based on a member of that group. As the name suggests, hasty generalisations are assumptions made quickly based on very few examples from a group. This is relative to the entire population that an assumption is being made about, which is far greater than the number of examples. Without thinking critically, it is easy to make such unreasonable assumptions about entire groups of people, which is of course the basis of prejudice and discrimination. In the interest of a fairer society, it is important to avoid such quick and unfair assumptions and to develop an awareness of how these prejudices are formed. Often, these are based on a lack of exposure to the group in question, only taking note when a member of that group does something wrong, and then only seeking out news and opinions that confirm this prejudice. This ultimately creates a distorted image of an entire group of people and leads to unfair judgement of individuals who have done nothing wrong.

Uncritical thinking could also be bad for your health. Newspaper reports and internet sites are often full of information about healthy living, especially concerning dieting and nutrition. These are subjects that many people are concerned with, and of course this stimulates the demand for such articles. While there is a lot of useful information out there, often there are articles promoting diets that are not based on any scientific evidence at all. Examining these critically, especially if an extraordinary or surprising claim is made, is essential for making sensible decisions when it comes to your health. Many sources are available to counter such dubious scientific claims and health advice (1), but it is also useful to be able to spot these independently. Without thinking critically, people may choose to follow unreasonable advice to the detriment of their health and well-being. In addition, this can lead to unnecessary worries about health and well-being, such as if symptoms are misdiagnosed or overinterpreted by a non-expert.

There are serious implications to this acceptance of ideas without challenge. As an example, the belief that vaccinations can lead to autism has resulted in outbreaks of measles in areas where previously there were no cases. If people believe unreliable and debunked research, instead of the overwhelming evidence that vaccinations have almost eradicated certain diseases, then there can be real and direct consequences. Influential people, such as those in charge of countries, organisations or those with a large following, can easily spread such information to the masses. Teaching critical thinking to the general population would therefore be beneficial, in order to reduce the spread of misinformation.

More generally, without examining your own thoughts or beliefs, how can they really be your own? Without reflecting upon such things, these opinions are never truly yours, but rather the product of influences from society, culture, friends and family. Therefore, the life you lead and the decisions you make are not under your control and are subject to the beliefs of others. This can result in not acting in your own best interests and could in fact sabotage your hopes and aspirations.

What could be taught?

Would it be possible to teach a subject as broad as critical thinking in school? Possibly, but it would be more practical and expedient to teach it as part of all of the main subjects. In science class, besides learning rules and formulae, it should also be possible to spend time assessing the evidence for knowing the information that is being taught. Additionally, there could be an emphasis on how science connects with society, demonstrating the power that critical thinking has to improve people’s lives. In language lessons, part of the curriculum could focus on argument structures, identifying the different components of arguments in real world examples, such as from newspapers or internet stories. In mathematics, greater attention could be paid to logic, and how mathematical logic relates to propositional logic, again with real world examples to reinforce the theoretical material.

Of course, it would also be beneficial to have part of the school timetable dedicated entirely to critical thinking, in order to teach the basics of argumentation, incorrect argument structures and logical fallacies. Debating skills, which are already a part of some educational programmes, could be used to reinforce many of these points in a practical way. Most importantly, students would be taught why critical thinking is so important, highlighting the reasons discussed previously. Specifically, some of the following points could be taught as the basis of critical thinking.

How we know things and evidence for what we believe

Most of what we believe does not come from direct experience or observation. It is generally accepted that the Earth orbits the sun, although the vast majority of people don’t fully understand the laws of planetary motion, and almost nobody has seen this directly. However, this does not mean that it is untrue, only that it requires a theory, predictions, and validation of those predictions with data in order for it to be accepted. Alternative theories also exist, but these have far more complicated explanations that require more assumptions and involve several unknown forces, the properties of which are uncharacterized and don’t fit with other phenomena that have been described previously. With this in mind, the heliocentric model of the solar system seems far more likely than the alternative explanations.

While this example was related to science, the principles of assessing the truth of this claim can be used to assess any claim. Firstly, does the argument or claim make sense? This is called internal consistency, whether there is a contradiction within the argument that would make it impossible according to what is claimed. Secondly, does the argument fit with what is known already? This is external consistency and is usually what determines whether an argument is believed or not. If a claim completely goes against what is already known it is unlikely to be accepted by anyone.

Claims, statements, conclusions, and arguments

With such a vast amount of information it is often useful to simplify a text or articles into different components for clarity. Then it becomes easier to determine what the message of an article is, and what supports the claims that are made.

A claim is an assertion, stating that something is or is not the case. Usually this is easy to identify as it is often a part of a title or is mentioned in the opening sentences. A conclusion is what the ‘take home’ message of an argument is and should be supported by other statements in the text, known as premises. Premises are statements that support the conclusion and are the main components of an argument. An argument is a series of statements, in which some statements, known as premises, support another statement, the conclusion.

Common fallacies

Many persuasive techniques are used to influence the opinion of a reader. Indeed, writing persuasively is essential for engaging with readers, but many of these are based on logical fallacies. Although they seem convincing, they don’t actually demonstrate whether something is true or not. They are irrelevant. Below are a few common examples to look out for.

Appeal to popularity/tradition/emotions

These three fallacies share a similar theme, they appeal to something that does not necessarily support the conclusions of an argument. Just because many people believe something doesn’t make it true (appeal to popularity). Similarly, if something is part of a tradition it also does not follow that it is true (appeal to tradition). Appeals to emotion are difficult to combat and probably provides the most difficult obstacle to critical thinking. Having strong feelings about something does not provide support for a conclusion being true. It is important to mention that none of these fallacies make an argument untrue, only that they do not provide evidence or support for the argument that is being made.

Strawman fallacy

When arguing with a person or group, attempts are often made to try to discredit or misrepresent their argument. Sometimes, instead of addressing the argument, an alternative (usually unconvincing) argument is addressed to make it seem as though that was the original point of contention. This is called the strawman fallacy. This is closely related to the ad hominem argumentative fallacy, in which the person or group making the claims are criticised, and not the argument itself. Both of these are similar since they are not addressing the argument at all and are an attempt at distracting from the points being made.

Confirmation bias

With a pre-existing belief or bias it is easy to notice things that confirm or support this idea, and this is known as confirmation bias. This is inappropriate because you only pay attention to things that support your idea and ignore anything that does not support or contradicts the belief. As well as affecting scientists who are searching for evidence to support their pet theory, this is also inappropriately used as ‘evidence’ to support common stereotypes.

Hasty generalisation

As mentioned previously, the hasty generalisation is a rapid generalisation made about a group based on characteristics of very few members from that group. The logic follows that if a certain representative sample from a population exhibit certain features, then it is likely that the entire population will exhibit those features. This is a valid method for determining things statistically and is used in clinical trials to determine what effect a drug will have on a larger population. However, the error is made when a sample is neither representative nor large enough to draw firm conclusions about a group. This false thinking is often used when supporting prejudice and discrimination against groups of people.


Critical thinking is clearly an extremely important skill and can be broadly applied to most aspects of life. Basic education generally focuses on learning facts and retaining information in order to pass exams in order to gain qualifications, which is much less useful for most people in everyday life. Therefore, people would greatly benefit from an education less focused on simply teaching subject details and more focused on critical thinking, which would better equip them for the information-rich age in which we now live.


Robert Ganley



A relevant read: Vaughan, L., “The Power of Critical Thinking: Effective reasoning about ordinary and extraordinary claims.”, Oxford University Press, 2018.

  1. Goldacre, B., “Bad Science”, Fourth Estate, 2009.
Received: 28.05.19, Ready: 04.07.19, Editors: HH, AFB.


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