Critical thinking is purposeful, self-regulating judgement: working out what a claim means, what reasons support it, how good those reasons are, and what conclusion they actually justify — then being able to explain that reasoning to someone else. It is not the same as being clever, and it is not the same as being sceptical of everything. It is the habit of checking a conclusion before you accept it, including your own.
The definition experts agreed on
The most widely used definition comes from a single document. In 1990 the philosopher Peter Facione convened a panel of 46 scholars, educators and assessment researchers for the American Philosophical Association and ran it as a Delphi study: several rounds in which each expert answered, read the others' reasoning and revised, until the panel converged. About half the panel came from philosophy; the rest from education, the social sciences and the physical sciences.
The result, known as the Delphi Report, split critical thinking into two parts that later research has kept apart: a set of cognitive skills, and a set of dispositions — the inclination to actually use those skills. The distinction matters for everything that follows. A person can have the skills and not the habit.
The core critical thinking skills
The consensus names six. Lists of “five core skills” group the same abilities differently.
| Skill | What it means | The question it asks |
|---|---|---|
| Interpretation | Understanding what a statement, chart or event means | What exactly is being claimed? |
| Analysis | Separating the claim from the reasons offered for it | What is the argument, and what does it rest on? |
| Evaluation | Judging how credible the sources and how strong the reasons are | Should I believe the premises, and do they support the claim? |
| Inference | Drawing the conclusion the evidence justifies — no more | What follows, and what else could explain this? |
| Explanation | Stating your reasoning so that someone else can check it | Could I defend this conclusion to a sceptic? |
| Self-regulation | Monitoring and correcting your own thinking | Where would I be most likely to be wrong? |
Examples of critical thinking
- A health headline. A food “halves your risk” of a disease. Halves it from what to what? A fall from two in 10,000 to one in 10,000 is a halving, and almost nobody's decision should change because of it. Was it an experiment, or an observation of people who happened to eat the food?
- A workplace decision. A project failed and the team agrees on the cause within five minutes. Critical thinking asks what evidence would distinguish that explanation from the next most likely one — and whether anyone looked.
- A persuasive argument you agree with. The hard case. Checking the reasoning of a conclusion you already hold is where the self-regulation skill does its work, and where most people skip it.
Are critical thinkers smarter? Critical thinking vs IQ
This is the question an intelligence site should answer, and the evidence says the two overlap less than people expect.
An IQ test measures how well you reason when a task demands it: it hands you a problem, tells you there is a right answer and waits. Everyday critical thinking rarely announces itself that way. Nobody tells you that the article you are reading contains a flawed inference. Whether you notice depends on the dispositions the Delphi panel described — and those are not what an intelligence test scores.
Keith Stanovich and Richard West tested the overlap directly. Across seven studies, they found that a large number of classic thinking biases are uncorrelated with cognitive ability — anchoring, framing effects, myside bias, the sunk-cost effect and others. Ability did correlate with avoiding a smaller set, such as belief bias and probability matching. Their conclusion is in the paper's title: thinking biases and cognitive ability are relatively independent.
Research on outcomes points the same way. In a 2012 validation study, Heather Butler gave the Halpern Critical Thinking Assessment to 133 US community adults and college students and asked about real events in their lives — in education, health, law, finance and relationships. Higher critical thinking scores went with fewer negative life events, r = −.38. A 2017 follow-up by Butler and two colleagues compared the two abilities as predictors; its title states the result: “Critical thinking ability is a better predictor of life decisions than intelligence”.
None of this makes intelligence irrelevant. Reasoning ability is the raw material, and a person who cannot follow an argument cannot evaluate it. The point is narrower: a high score does not guarantee the habit of using it on your own beliefs. The same gap explains why cognitive biases affect able people and why the Dunning-Kruger effect is about self-assessment rather than intelligence.
Can critical thinking be taught?
Yes — modestly, and mostly when it is taught deliberately. This is one of the better-studied questions in education research.
- 2008: Philip Abrami and colleagues pooled 117 studies with 20,698 participants and found an average effect of g = 0.341. The type of intervention and its teaching approach explained 32% of the variation. Their conclusion: improvement in critical thinking “cannot be a matter of implicit expectation” — it has to be an explicit goal.
- 2015: The same group, with 341 effect sizes, found an average of g = 0.30, at every educational level and in every subject area studied. Three things stood out: dialogue, authentic problems and examples, and mentoring.
- 2016: Christopher Huber and Nathan Kuncel found that both critical thinking skills and dispositions improve substantially over an ordinary college education — but that curriculum-wide programmes aimed specifically at critical thinking did not necessarily add long-term gains on top.
An effect of 0.30 is real and worth having; it is not a transformation. Diane Halpern's 1998 model is built around the hard part, transfer — using a skill outside the subject it was learned in. Her four ingredients are a disposition to think carefully, practice in the skills themselves, training in recognising the structure of a problem so that you spot it in a new setting, and monitoring your own thinking as you go.
How to improve your critical thinking
Practical habits that follow from that research rather than from motivational writing:
- Argue with someone who disagrees. Dialogue was one of the three strongest ingredients in the 2015 meta-analysis. Reading alone lets you skip the objections.
- Practise on real material, not puzzles. Authentic problems transferred better. Take a claim from today's news and run the six questions in the table above.
- Name the structure. “This is a correlation being reported as a cause” is a pattern you will meet again in a different subject. Naming it is what lets it transfer.
- Write down what would change your mind before you look at the evidence. It is the most direct way to exercise self-regulation.
Critical thinking tests
Critical thinking is measured with tests built for it, not with IQ tests. The best known are the Watson-Glaser Critical Thinking Appraisal, used in hiring; the California Critical Thinking Skills Test; and the Halpern Critical Thinking Assessment, the test used in the Butler studies above. Employers use them alongside general cognitive ability tests, which measure something related but different.
Trust and scope notes
This page is educational. It summarises published research on critical thinking and its teaching; it is not a psychological assessment of anyone.
Our IQ test measures reasoning performance. It does not measure critical thinking, and a score does not tell you how carefully you check your own conclusions. What an IQ score does and does not cover is set out in how IQ tests work, and the different abilities people mean by “intelligence” in types of intelligence.
IQ Revealed is not affiliated with, endorsed by or connected to the American Philosophical Association, the American Psychological Association, the American Educational Research Association, Pearson (publisher of the Watson-Glaser appraisal), Insight Assessment (publisher of the California Critical Thinking Skills Test), the publishers of the Halpern Critical Thinking Assessment, or any of the universities, journals or researchers named on this page. Test names are trademarks of their owners and are named only to describe them. Quoted phrases are taken from the published titles and abstracts of the works linked in the sources.