Definition
Critical thinking is the disciplined practice of evaluating claims, evidence, and reasoning before deciding what to believe. It is not the same as being negative or contrarian; it is the habit of asking how a claim is supported, what would count against it, and whether the conclusion actually follows from the premises.
It is called a discipline because it has to be applied deliberately and against natural inclination. The default human response is to accept claims that fit existing beliefs and reject those that do not. Critical thinking is the conscious effort to interrupt that default and judge a claim on its merits.
Why it matters
How it works
Critical thinking proceeds by a small set of repeatable questions. What exactly is being claimed? Who says so, and how would they know? What evidence supports it, and is that evidence primary or hearsay? What would the world look like if the claim were false? Does the conclusion follow, or is a step missing?
Applied honestly, this routine slows judgment just enough to catch the errors that fast, intuitive thinking lets through. Its hardest application is inward: a critical thinker subjects favoured beliefs to the same scrutiny as unwelcome ones, which is precisely where confirmation bias resists.