How and why of critical thinking?

We often urge others to think critically. What does that really mean? How can we think critically?

This essay presents a general account of what it is to be a critical thinker and outlines both traditional and more recent approaches to critical thinking.Know the Facts: A WPA (Works Progress Administration, part of the New Deal) poster, imploring the public to develop critical thinking skills. Circa late 1930-early 1940s.

1. What is Critical Thinking?

Speaking generally, critical thinking consists of reasoning and inquiring in careful ways, so as to form and update one’s beliefs based on good reasons.^[1] A critical thinker is someone who typically reasons and inquires in these ways, having mastered relevant skills and developed the disposition to apply them.^[2]

2. Traditional Components: Logic and Fallacies

Traditional views of critical thinking focus on deductive arguments. Arguments are sets of reasons given for a conclusion. Deductive arguments are arguments where the reasons given are supposed to be logically conclusive, that is, to guarantee the conclusion. E.g., the following is a deductive argument:

1. Socrates is a man.
2. All men are mortal.
3. Therefore, Socrates is mortal.

Arriving at new beliefs through deductive arguments is a way of forming beliefs based on good reasons. Accordingly, critical thinking traditionally focusses on these skills:^[3]

• distinguishing arguments (instances where you are offered reasons for a conclusion) from mere assertions, rhetorical questions, and attempts at manipulation through irrelevant considerations;
• identifying conclusions of arguments (what the person offering the argument wants to persuade you to believe), and the reasons or premises for that conclusion;
• reconstructing streamlined, complete statements of arguments in standard form (as a numbered list of premises with the conclusion at the end), or using diagrams;^[4]
• assessing the logical structure of deductive arguments: answering ‘Is there any way for the premises to be true while the conclusion is false?’
• understanding arguments’ claims: e.g., defining unclear terms;
• determining whether premises are true or likely;
• imagining, proposing, and charitably responding to objections, i.e, reasons given to doubt or deny arguments’ logic, premise(s), or conclusion.^[5]

To develop these skills, traditional critical thinking courses typically include propositional logic and the study of common good argument forms.^[6]

They also often teach how to identify fallacies—faulty patterns of reasoning that deceptively appear to be good arguments.^[7] These include: 

• affirming the consequent (“If Kat had won the prize, she would have had an A; Kat had an A; therefore, Kat won the prize”);
• the ad hominem fallacy—where people attack the person making an argument instead of considering their argument; 
• begging the question—offering reasons for a conclusion that assume the conclusion, and many others.^[8]

3. Additional Formal Tools: Evidence and Statistics

We often form beliefs based on observations that, unlike deductive arguments, do not provide conclusive reasons for a belief: e.g., you might conclude that your sibling is angry at you from their facial expressions or come to believe you have a cold because you have a runny nose. Here, these observations or evidence might support the belief formed but do not guarantee the truth of your belief.

Critical thinkers know how to adjust their beliefs appropriately in light of their evidence.^[9]So critical thinking requires developing abilities to:

• assess evidence without being unduly swayed by what one already believes;
• recognize when a claim counts as evidence for (or against) a conclusion;
• identify when evidence is strong (or weak);
• determine the extent to which people’s views should change, given their evidence.

To develop these abilities, drawing on knowledge of probability can be helpful: e.g., basic probability offers a recipe for determining when an observation counts as evidence for a belief: when that observation is more likely if the belief is true than if it is not. It also teaches us that updating your beliefs when you get new evidence requires taking into account both (a) how confident you were on that belief beforehand and (b) how strongly the evidence supports that (new) belief.^[10]

For these reasons, recent approaches to critical thinking often include instruction in probability.^[11] And, because we often get evidence in the form of statistics, often presented through diagrams and graphs, such approaches tend to highlight the importance of basic statistical concepts,^[12] and the ability to interpret diagrams and graphs.^[13]

4. Applied Skills as Part of Being a Critical Thinker

Being a critical thinker requires more than having technical tools (such as the tools of logic or probability) stored away. It requires consistently applying them in the real world.

In recent discussions of what it is to be a critical thinker, there has been increased emphasis on navigating our informational environments in savvy ways. This requires avoiding false, misleading, manipulative, or distracting claims online, as well as making sure that one gathers information from a wide variety of reliable sources.^[14] It also requires calibrating one’s trust well: one should remain open to hearing those who disagree and not let prejudice and implicit bias affect whom one trusts.^[15],[16]

Applying the tools of critical thinking throughout one’s life requires overcoming cognitive biases:^[17] e.g.: 

• not always accepting answers that come to mind first; 
• resisting confirmation bias (the tendency to gather and interpret evidence in ways that confirm our beliefs),^[18] and;
• avoiding motivated reasoning (the tendency to reason in ways that help us believe what we wish were true, and not what is true).^[19]

More generally, becoming a critical thinker requires shifting from a defensive mindset to a truth-seeking one and developing intellectual virtues such as intellectual humility and open-minded curiosity.^[20],[21] Without those, the tools of critical thinking may end up being deployed to entrench false or unreasonable beliefs.

5. Conclusion

Critical thinking is about reasoning and inquiring so as to form and update one’s beliefs based on good reasons. Because critical thinking skills are valuable in a world that emphasizes the ability to navigate information, becoming a critical thinker is practically useful to us as individuals. 

It is also of crucial social and political value: e.g., a well-functioning democracy requires citizens who think critically about the world.^[22] And critical thinking has liberatory potential: it provides us with tools to criticize oppressive social structures and envisage a more just, fair society.^[23]