When it comes to the topic of critical thinking, the most searched for related term is “critical thinking definition.” Over 18,000 people each month use Google to try to find out what critical thinking is. Why are so many people seeking a simple, yet compelling definition for critical thinking?

Because they want to become better critical thinkers but aren’t sure what it is exactly. And it’s difficult, if not impossible, to make it to a destination you can’t describe. In a recent article we published in Harvard Business Review, we said: “that there is little agreement around what critical thinking is.” In response, one person argued that we were wrong. In fact, she said that a group of experts spent 22 months working together to come to a consensus around what critical thinking is back in 1988.

Here’s what they concluded:

We understand critical thinking to be purposeful, self-regulatory judgment which results in interpretation, analysis, evaluation, and inference, as well as explanation of the evidential, conceptual, methodological, criteriological, or contextual considerations upon which that judgment is based.

Critical Thinking: A Statement of Expert Consensus for Purposes of Educational Assessment and Instruction

And that’s only half of their definition. While we appreciate their contribution to the conversation (and will share more from their report later in this article), we can see why their expert definition has done little to clear up the confusion in the last ~30 years. The problem with their definition, aside from containing at least half a dozen words the average person would also need to define, is that it doesn’t clarify what it means to do good critical thinking.

Why Definitions Matter

And that is really the point of a definition for the average person. Consider how we use “definitions” in society. If we asked you to define the word “ball” or “red,” you would be hard-pressed to define it except by giving examples. For ball, you may begin by suggesting that it is something that is round or spherical, but eventually, you would realize that you had just excluded the American football. Almost no one would be able to provide a simple definition of these words, yet nearly everyone can recognize them when they see them. Nouns, such as critical thinking, are inherently difficult to define in literal, dictionary-style ways. (Shane Parrish of Farnam Street does a good job further unpacking this concept.)

But in reality, dictionary definitions rarely help us. Instead, average people require a more practical, functional definition that enables them to recognize the person, place, or thing when they see him/her/it. When it comes to critical thinking, we want to know great critical thinking when we see it and importantly, know what distinguishes great critical thinking from poor critical thinking.

The work we did to create the Critical Thinking Roadmap Toolkit gets us part of the way there with its four phases and clearly articulated milestones for each phase. Yet, the emphasis was more on the journey than the destination. To arrive at a practical definition of critical thinking that does more to illuminate the destination, we looked to 10 different definitions of critical thinking:

Critical Thinking Definitions: 1910-2019

John Dewey, one of America’s leading philosophers, advocate for public schools and an intellectual approach to intellectual development says in his 1910 book How We Think:

The essence of critical thinking is suspended judgment; and the essence of this suspense is inquiry to determine the nature of the problem before proceeding to attempts at its solution. This, more than any other thing, transforms mere inference into tested inference, suggested conclusions into proof.

John Dewey in How We Think (1910)

Edward Glaser, a management consultant whose dissertation led to the development of the Watson-Glaser Critical Thinking Appraisal, defined critical thinking this way in his 1941 book, An experiment in the development of critical thinking:

The ability to think critically, as conceived in this volume, involves three things: (1) an attitude of being disposed to consider in a thoughtful way the problems and subjects that come within the range of one’s experiences, (2) knowledge of the methods of logical inquiry and reasoning, and (3) some skill in applying those methods. Critical thinking calls for a persistent effort to examine any belief or supposed form of knowledge in the light of the evidence that supports it and the further conclusions to which it tends.

Edward Glaser in An experiment in the development of critical thinking (1941)

When Glaser joined with Watson and created the well-known psychological test of critical thinking ability, the Watson-Glaser Critical Thinking Appraisal, they updated their definition somewhat:

Critical thinking is a composite of attitudes, knowledge and skills. This composite includes: (1) attitudes of inquiry that involve an ability to recognize the existence of problems and an acceptance of the general need for evidence in support of what is asserted to be true; (2) knowledge of the nature of valid inferences, abstractions, and generalizations in which the weight or accuracy of different kinds of evidence are logically determined; and (3) skills in employing and applying the above attitudes and knowledge.

Goodwin Watson and Edward Glaser in Watson-Glaser Critical Thinking Appraisal (1980)

Robert Ennis, a professor emeritus from the University of Illinois, described critical thinking this way in his 1987 essay, “The Nature of Critical Thinking”:

Critical thinking is reasonable reflective thinking that is focused on deciding what to believe or do.

Robert Ennis in “The Nature of Critical Thinking” (1987)

Michael Scriven & Richard Paul presented this definition at the 8th Annual International Conference on Critical Thinking and Education Reform in 1987:

Critical thinking is the intellectually disciplined process of actively and skillfully conceptualizing, applying, analyzing, synthesizing, and/or evaluating information gathered from, or generated by, observation, experience, reflection, reasoning, or communication, as a guide to belief and action.

Michael Scriven & Richard Paul (1987)

The Delphi Project’s X experts agreed on this definition of critical thinking in 1990:

We understand critical thinking to be purposeful, self-regulatory judgment which results in interpretation, analysis, evaluation, and inference, as well as explanation of the evidential, conceptual, methodological, criteriological, or contextual considerations upon which that judgment is based.

Delphi Project (1990)

Diane Halpern, the educational professor who created one of the most research-validated critical thinking assessments defined it at one point like this:

Critical thinking is the use of those cognitive skills or strategies that increase the probability of a positive outcome.

Diane Halpern

Sharon Bailin, a professor emerita from Simon Fraser University said in 1999 in her book, Reason in Balance:

Educators typically understand critical thinking to have at least three features.

1 – It is done for the purpose of making up one’s mind about what to believe or do.

2 – The person engaging in the thinking is trying to fulfill standards of adequacy and accuracy appropriate to the thinking.

3 – The thinking fulfills the relevant standards to some threshold level.

In short, critical thinking is careful goal-directed thinking.

Sharon Bailin in Reason in Balance (1999)

Richard Paul joined forces with Linda Elder, an educational psychologist and president of the Foundation for Critical Thinking, to share this concise definition in their book, The Miniature Guide to Critical Thinking Concepts and Tools, which was published by the Foundation for Critical Thinking Press in 2008:

Critical thinking is, in short, self-directed, self-disciplined, self-monitored, and self-corrective thinking.

Richard Paul & Linda Elder in The Miniature Guide to Critical Thinking Concepts and Tools (2008)

Linda Elder, then, more recently emphasized the meta-cognition characteristic of critical thinking in 2014:

Thinking about your thinking, while you’re thinking, in order to improve your thinking.

Linda Elder as quoted in “Booses Seek ‘Critical Thinking’, but What is That?” (2014)

A Simple, Practical Definition of Critical Thinking

We recognize several similarities in these definitions (side note: we’re now demonstrating the second phase of the critical thinking roadmap, synthesize):

• Critical thinking answers a question: Bailin calls it “goal-directed thinking,” while Ennis says it is “focused on deciding what to believe or do” and Dewey says the essence of critical thinking is “determining the nature of the problem” one is trying to solve. The Delphi Project calls critical thinking “purposeful.”
• Critical thinking is rigorous: Paul and Elder describe it as “self-disciplined” and “self-corrective.” The Delphi Project describes critical thinking as “self-regulatory judgment.” Paul, later with Scriven, calls it an “intellectually disciplined process.”

Critical thinking is the development of a robust answer to a question.

A good critical thinker, then, is someone who is very good at answering questions, someone you would trust to answer your questions. By robust, we mean that the answers of a sharp critical thinker would stand up under the scrutiny of outside examination. Their answers are well-reasoned, objective, sound, and rigorous.

Questions Critical Thinking Answers

The questions critical thinking may be directed at answering can take many forms. Here are several examples, highlighting several, overlapping critical thinking skills:

• Interpretation: What does this mean?
• Evaluation: Is this right or good?
• Problem-solving: What is the solution to this problem?
• Strategic thinking: How do we achieve our goal?
• Creative thinking: What new thing will help us achieve our goal?
• Decision-making: Which option is best?
• Probability: What are the chances this will happen?
• Logic: Does this make sense?

The questions may be explicit, like when a coworker asks what you think of the proposal she has developed, or the questions can be implicit. For example, a client shares their plans for expanding internationally and then pauses for your response.  Your client is asking a question by giving space for your reaction.

Does critical thinking require expertise?

Questions from your client may seem straightforward, but not all questions you encounter will fall in your area of expertise. This begs an important question: if critical thinking is about developing robust answers to questions, then do people need to know a lot about many topics to be a good critical thinker? For example, would a good critical thinker be able to develop robust answers to both of these questions?

• I am a fund manager at an investment firm. Should I move X% of the fund’s assets into this new investment opportunity?
• I am a wedding photographer. How much should I charge for my premium photo package?

Most academics would say, “Yes. A good critical thinker could answer both robustly” because they consistently describe critical thinking a cross-cutting skill that doesn’t require domain-specific expertise. Yet, it still may seem unlikely that one person without the relevant expertise could answer both of these questions intelligently.

Sharp critical thinkers could, however, because they know what questions to ask. Questions guide our thought processes like a map. If you ask good questions, you’ll make your way to robust answers. (You can find 100 questions that will build your critical thinking skills here.) A unique set of questions govern each of the critical thinking skills mentioned above, like interpretation and decision-making. Sharp critical thinkers learn those questions and then apply them when confronted with a question of the corresponding type.

Sharp critical thinkers don’t just ask these questions of themselves, keeping them in their own head. They often lead conversations with the questioner with a question. Socrates, perhaps the most well-known for this, used this approach to assess the wisdom of politicians, poets, and skilled craftsmen. These three groups conceivably spanned a wide range of expertise that would far exceed what Socrates himself could have committed to memory. Yet, by asking the right questions, he was able to unpack their ideas and reveal inconsistencies in their thinking.

If you want to know the questions to ask for the different kinds of questions you’re responsible for answering, start by understanding our critical thinking roadmap and the 100 critical thinking questions that map onto the roadmap.

We’ve begun to describe the critical thinking skills mentioned above in more detail. We’ll be describing each of the 16 skills in more depth over time. If that’s of interest to you and you haven’t already, sign up for our newsletter and we’ll make sure you know about it when it’s available.

Quick Summary

What is critical thinking?