By Michael Ireland, adapted by Marc Chao and Muhamad Alif Bin Ibrahim

Critical thinking has been defined as purposeful reflecting and reasoning about what to do or believe when confronting complex issues, taking into account relevant context. It involves a diligent process of scrutinising beliefs or claimed knowledge against the backdrop of supporting evidence and potential outcomes.

To think critically, it is essential to adopt critical thinking skills and dispositions. Dispositions are the inherent qualities or tendencies that shape how we think and act. In the context of critical thinking, dispositions such as subject matter knowledge, metacognition (thinking about thinking), curiosity, intellectual honesty, and open-mindedness are crucial. These traits influence our approach to information and ideas, guiding us to engage thoughtfully and critically. As you read this chapter, consider how these dispositions might apply to your own thinking. Reflect on whether you are open to revising your beliefs when presented with strong evidence, whether you actively seek out perspectives that challenge your views, and whether you regularly think about how you make decisions. This brief reflection can help you become more aware of your strengths and areas where you might develop your critical thinking dispositions further.

Critical thinking encompasses several key skills or abilities, such as recognising problems, gathering and marshalling pertinent information, and interpreting data to appraise evidence and evaluate arguments. It also involves recognising unstated assumptions and values, comprehending and using language with accuracy, and drawing warranted conclusions and generalisations. By putting these conclusions to the test and reconstructing our patterns of beliefs based on wider experience, we can render accurate judgements about specific things and qualities in everyday life.

Critical Thinking Dispositions

A solid understanding of the subject matter provides the foundation for critical thinking, while dispositions such as metacognition, curiosity, intellectual honesty, and open-mindedness shape how we engage with that knowledge. These dispositions are essential psychological traits that influence how we approach and engage with information and ideas.

Subject Matter Knowledge

To think critically, it is essential to have a solid grasp of the subject matter. However, this alone is not enough. Equally important is our ability to be self-aware and introspective, a process known as metacognition. This involves scrutinising newly acquired information and reflecting on our understanding of it. The effectiveness of our critical thinking is closely tied to our foundational knowledge and our willingness to engage deeply with that knowledge.

For instance, a student might possess extensive knowledge about a particular topic but may have acquired this knowledge passively, without any reflection or contemplation. In such cases, critical thinking has not been activated. True critical thinking requires an active engagement with the material, questioning assumptions, and considering the implications of what has been learned.

Active involvement in learning processes significantly enhances critical thinking skills. When students participate actively in class through activities such as peer reviews, classroom presentations, small group discussions, film reviews, or laboratory exercises, they are more likely to develop and refine their critical thinking abilities. These interactive and participatory methods encourage students to think deeply about the subject matter, challenge their own and others’ assumptions, and apply their knowledge in practical, meaningful ways.

Metacognition

Metacognition is the awareness and regulation of one’s own thinking processes. It involves a deep understanding of what you know, what you do not know, and how you can improve your thinking. This self-awareness allows you to monitor, evaluate, and adjust your reasoning strategies effectively.

By engaging in metacognition, you can identify your strengths and weaknesses, set meaningful goals, plan your actions thoughtfully, check your progress regularly, and reflect on your outcomes. This reflective practice not only enhances your critical thinking skills but also fosters a mindset of continuous improvement.

Metacognition also plays a vital role in helping you become more open-minded, curious, and flexible in your thinking. It enables you to recognise your assumptions, biases, and perspectives, and to challenge them with evidence and logic. This self-scrutiny encourages intellectual honesty and a willingness to revise your beliefs based on new information.

Furthermore, metacognition involves seeking feedback, learning from others, and exploring different viewpoints. By being open to diverse perspectives, you can broaden your understanding and develop a more nuanced view of complex issues. This collaborative approach to learning and thinking enhances your ability to evaluate information critically and make informed decisions.

Curiosity

Curiosity serves as the driving force that motivates us to explore and understand the world around us. It propels us to delve deeper into the problems we encounter and to seek out new knowledge and insights. Curiosity encourages us to question assumptions and challenge the status quo, rather than passively accepting things as they are or dismissing them outright.

This inquisitive nature is essential for critical thinking because it stimulates our desire to learn and discover. When we are curious, we are more likely to engage in thoughtful inquiry and to connect disparate pieces of information in innovative ways. This process of connecting the dots often leads to new discoveries and creative solutions to complex problems.

Moreover, curiosity opens us up to a world of possibilities and opportunities for problem-solving and innovation. It fosters a mindset that is receptive to new ideas and perspectives, enabling us to approach challenges with a fresh and open mind. By being curious, we not only enhance our understanding of the world but also cultivate the ability to think critically and creatively.

Scepticism

Scepticism is characterised by the practice of suspending judgement. This means not rushing to conclusions but instead waiting until you have gathered a sufficient amount of relevant evidence and reasoning on an issue. To be sceptical is to withhold making decisions about the truth of claims until you have thoroughly examined the reasoning and evidence using the conceptual tools of critical thinking. It is not about automatically disbelieving everything but about maintaining a neutral stance until you can arrive at a defensible position.

This approach is more challenging than it might seem because humans are hardwired to react quickly to incoming information and situations, often making snap decisions about what to accept and how to respond. All too often, we jump to conclusions with only partial information. Our beliefs and disbeliefs are frequently knee-jerk reactions based on faulty reasoning, such as gut feelings or first impressions. Being sceptical means going through the steps of critical thinking, such as analysing meaning, logic, and argument, applying scientific methods and evidence, identifying fallacies and biases, and considering decisions and values, before forming a conclusion about a claim.

Scepticism can sometimes be perceived as a lack of commitment, and it can be difficult to maintain a neutral stance, especially when under pressure from social networks or when strong emotions are involved. This is why practising scepticism requires effort and persistence. It is important to remind yourself of the benefits of scepticism, such as avoiding gullibility and premature conclusions. Be prepared to endure the discomfort of uncertainty until you are satisfied that there is sufficient reason and evidence to take a position.

Scepticism is particularly necessary for ideas and information that are immediately appealing. Many ideas bypass our critical thinking filters because they align with our existing beliefs, such as our political, ideological, or religious views. We need to be most sceptical about ideas we want to be true. It is no accident that our interpretations are often consistent with our existing beliefs. We are almost incapable of interpreting an ambiguous event in a way that contradicts our worldview. This is because any concept, event, or interaction can be interpreted in numerous ways, allowing us to mould our interpretations to fit our belief systems. Being aware of this tendency is crucial, and it is important to critically examine and interrogate all beliefs, especially those that have not been fully scrutinised.

There are two prevalent forms of scepticism: commonsense scepticism and philosophical scepticism.

Common sense scepticism refers to the everyday practice of questioning and doubting claims until there is sufficient evidence to support them. This form of scepticism is practical and grounded in daily experiences. For example, if someone tells you that a new restaurant in town serves the best food, common sense scepticism would lead you to seek reviews, ask friends for their opinions, or try the food yourself before accepting the claim. Common sense scepticism helps us navigate the world by preventing us from being easily deceived and encouraging us to verify information before accepting it as true.

Philosophical scepticism, on the other hand, is a deeper and more systematic approach to doubt. It involves questioning the very foundations of knowledge and belief. Philosophical sceptics challenge the possibility of certainty in knowledge, asking whether we can truly know anything at all. For instance, René Descartes, a famous philosophical sceptic, doubted everything he believed until he reached the conclusion “Cogito, ergo sum” (I think, therefore I am). This form of scepticism is not about practical decision-making but about exploring the limits and nature of human knowledge. Philosophical scepticism can lead to deeper insights into the nature of reality and our understanding of it, but it can also result in radical doubt, where one questions the validity of all beliefs.

The key difference between commonsense and philosophical scepticism lies in their scope and application. Common sense scepticism is practical and applied to everyday situations, helping us make informed decisions based on evidence. For example, questioning the authenticity of a news article before sharing it is an act of common sense scepticism. Philosophical scepticism, however, is more abstract and theoretical, questioning the very possibility of knowledge itself. An example of philosophical scepticism is doubting the existence of the external world independent of our minds, as proposed by some philosophers who argue that all we know are our perceptions, which might not correspond to an external reality.

For the purposes of this book, whenever we refer to scepticism, we are referring to common sense scepticism.

Intellectual Honesty

Intellectual honesty embodies the values of objectivity, fairness, and sincerity in our thought processes. It involves a steadfast commitment to seeking the truth, even when it is inconvenient, uncomfortable, or contrary to our pre-existing beliefs. This dedication to truth is essential for avoiding errors, biases, and fallacies in our reasoning.

Practising intellectual honesty means acknowledging our limitations and being willing to admit our mistakes. It requires us to correct our misconceptions and continuously strive for a more accurate understanding of the world. This openness to self-correction is crucial for refining our critical thinking skills and ensuring that our judgements are based on sound reasoning and reliable evidence.

Evaluating the credibility and validity of sources, arguments, and evidence is another key aspect of intellectual honesty. It involves a rigorous assessment of the information we encounter, questioning its origins, and scrutinising its reliability. By doing so, we can discern between well-founded arguments and those that are flawed or misleading.

Intellectual honesty also fosters respect and appreciation for different perspectives, opinions, and experiences, provided they are grounded in facts and logic. This respect for diverse viewpoints enhances our ability to think critically by exposing us to a broader range of ideas and encouraging us to consider alternative explanations and solutions.

Open-Mindedness

Open-mindedness embodies the willingness to consider different ideas, opinions, and perspectives, even when they challenge our own. This openness is crucial because it helps us to avoid prejudice, bias, and dogmatism in our reasoning. By embracing open-mindedness, we can acknowledge the complexity and diversity of the world we live in and appreciate the value of multiple viewpoints.

Being open-minded means actively seeking out new information and being willing to learn from others. It involves a readiness to revise our beliefs based on evidence and logic rather than clinging to preconceived notions. This flexibility in thinking allows us to adapt to new situations and to understand issues from various angles, enhancing our overall critical thinking abilities.

Open-mindedness also fosters a sense of curiosity and exploration. When we are open to different perspectives, we become more curious about the world around us and more eager to explore new ideas. This curiosity drives us to ask questions, seek out new knowledge, and engage in thoughtful discussions with others. It encourages us to connect with people who have different experiences and viewpoints, broadening our understanding and enriching our intellectual lives.

Moreover, open-mindedness promotes tolerance and empathy. By considering and respecting diverse perspectives, we develop a deeper appreciation for the experiences and opinions of others. This empathy helps us to build more inclusive and collaborative environments where different ideas can be shared and debated constructively. It also enables us to navigate conflicts and disagreements with greater understanding and respect.

Critical Thinking Skills

The second component of critical thinking is the skills component. Critical thinking is a multifaceted process that extends beyond merely possessing certain dispositions. While dispositions such as curiosity, intellectual honesty, and open-mindedness are essential, they are not sufficient on their own. To truly engage in critical thinking, one must also develop and apply a range of specific skills that enable deeper analysis and understanding. This involves the ability to interpret, analyse, evaluate, and infer, even when meanings and significance are not immediately apparent, as well as the ability to stay focused on the task at hand.

Analyse Arguments

Analysing arguments requires a comprehensive evaluation of various elements to determine the strength and validity of the argument presented. This process involves making inferences about the author’s intentions and perspectives, as well as assessing the logical structure, supporting evidence, and credibility of the information sources. Additionally, it is essential to consider counterarguments to ensure a balanced and thorough analysis.

To begin with, analysing an argument necessitates a deep understanding of both deductive and inductive reasoning. Deductive reasoning involves drawing logical conclusions from general premises or principles. A premise is a statement or idea that forms the basis for an argument. It is a top-down approach where the conclusion necessarily follows from the given premises if they are true. For example, if all humans are mortal (general premise) and Socrates is a human (specific case), then Socrates is mortal (logical conclusion). This form of reasoning is crucial for testing the validity of arguments and ensuring that conclusions are logically sound.

On the other hand, inductive reasoning is the process of inferring general patterns or rules from specific observations or cases. It is a bottom-up approach where conclusions are drawn based on the evidence available, though they may not be definitively proven. For instance, observing that the sun has risen in the east every morning leads to the general conclusion that the sun always rises in the east. Another example is noticing that every time you water your plants, they appear healthier and grow faster. From these specific observations, you might infer the general rule that regular watering promotes plant health and growth. Inductive reasoning is essential for generating new knowledge, forming hypotheses, and making predictions based on empirical data, which are facts and information gathered through direct observation or experimentation.

Evaluating the quality of an argument also involves scrutinising the evidence that supports it. This means examining the relevance, reliability, and sufficiency of the evidence presented. Reliable evidence is typically derived from credible sources, such as peer-reviewed journals, reputable experts, or well-conducted studies. It is important to assess whether the evidence is directly related to the argument and whether it is robust enough to support the claims being made.

Furthermore, analysing arguments requires considering the credibility of the information sources. This involves evaluating the expertise, objectivity, and potential biases of the sources. Credible sources are those that are recognised for their authority and reliability in the relevant field. It is also important to be aware of any potential biases that might influence the information provided, as these can affect the objectivity and accuracy of the argument.

In addition to evaluating the logic and evidence, it is essential to consider counterarguments. This involves identifying and examining alternative perspectives and objections to the argument. By addressing counterarguments, we can test the robustness of the original argument and ensure that it stands up to scrutiny. This process helps to refine our understanding and strengthen our reasoning by considering all relevant viewpoints.

As you have seen, this section describes arguments in a broad sense, as reasoned positions that require evaluating evidence, credibility, and counterarguments. This is only one aspect of understanding arguments in critical thinking. Later in this book, we will examine arguments in a more technical way, focusing on their formal structure as sets of statements where premises support a conclusion. Understanding both the broader evaluative process and the formal structure will equip you to analyse and construct arguments with greater precision.

Understand Statistics

Many of us often feel intimidated by the term ‘statistics’, associating it with complex formulas and calculations. However, in today’s age, psychology students are not expected to memorise statistical formulas. Instead, they can rely on software such as SPSS and JAMOVI to perform these calculations automatically. This shift allows us to focus on understanding the underlying statistical concepts, which are crucial for interpreting data and making informed decisions.

Understanding statistics provides the tools needed to collect, organise, analyse, and interpret data to make informed decisions based on evidence. Statistics plays a vital role in testing hypotheses, evaluating arguments, and drawing conclusions from data, making it an indispensable skill for critical thinkers.

One fundamental concept in statistics is the normal distribution. This is a bell-shaped curve that describes how values of a variable are distributed around the mean average. A variable is any characteristic, number, or quantity that can be measured or quantified. For example, if we measure the heights of a large group of people, most heights will cluster around the average height, with fewer people being very short or very tall. The normal distribution is particularly useful for critical thinking because it allows us to estimate the probability of observing certain values, compare different groups, and identify outliers or unusual values. By understanding the normal distribution, we can make more accurate predictions and better understand the variability within a dataset.

Another key concept is the distinction between correlation and causation. Correlation measures how two variables are related to each other, indicating whether an increase or decrease in one variable corresponds to an increase or decrease in another. For example, there might be a correlation between ice cream sales and drowning incidents, as both tend to increase during the summer. However, correlation does not imply causation, which is a stronger claim that one variable directly causes or influences another. In this case, the increase in ice cream sales does not cause more drownings; instead, both are influenced by the warmer weather. Understanding this distinction is crucial for critical thinking because it helps us explore relationships between variables, test causal hypotheses, and avoid logical fallacies or false assumptions. Just because two variables are correlated does not mean that one causes the other; there could be other underlying factors at play.

In addition to these concepts, critical thinkers must be adept at evaluating the quality of statistical evidence. This involves assessing the methods used to collect and analyse data, the sample size, and the potential biases that might affect the results. For example, if a study claims that a new drug is highly effective based on a small sample size of only 10 participants, a critical thinker would question the reliability of these results. They would consider whether the sample size is large enough to draw meaningful conclusions and whether the study design might have introduced any biases. By critically evaluating statistical evidence, we can determine the reliability and validity of the conclusions drawn from the data.

Furthermore, understanding statistics enables us to communicate findings effectively. Being able to interpret and present data clearly and accurately is essential for making persuasive arguments and informed decisions. This skill is particularly important in psychology, where data-driven insights are crucial for understanding human behaviour and developing effective interventions.

Evaluate Experimental Designs

Experimental designs are structured methods for conducting controlled experiments to test the effects of one or more factors on an outcome. Understanding these designs is essential because they help us establish causality, control for confounding variables, and measure the significance of results. A confounding variable is an external factor that can influence the experimental variables, potentially leading to incorrect conclusions about the relationship between them.

One common type of experimental design is the randomised controlled trial (RCT). In an RCT, participants are randomly assigned to either the treatment group or the control group. This randomisation helps ensure that any differences observed between the groups are due to the treatment itself and not other factors. For example, in a clinical trial testing a new medication, randomising participants helps control for potential confounding variables such as age, gender, and health status, which might otherwise influence the results. RCTs are considered the gold standard for testing the efficacy of interventions because they provide strong evidence of causality.

Another important experimental design is the factorial design. This approach allows researchers to test the effects of multiple factors simultaneously and to explore interactions between them. For instance, a study might investigate the combined effects of diet (factor 1) and exercise (factor 2) on weight loss (outcome variable) by assigning participants to different groups based on their diet and exercise regimens. Factorial designs are valuable because they can reveal how different factors (e.g., diet and exercise) interact and influence outcomes (e.g., weight loss), providing a more comprehensive understanding of complex phenomena.

Quasi-experiments are also widely used, particularly when randomisation is not feasible or ethical. In quasi-experiments, participants are not randomly assigned to groups, but the researchers still attempt to control for confounding variables through other means. For example, a study examining the impact of a new educational program might compare outcomes between schools that adopt the program and those that do not while accounting for differences in student demographics and school resources. Although quasi-experiments are less rigorous than RCTs, they can still provide valuable insights, especially in real-world settings where randomisation is impractical.