Cognitive skill

Critical Thinking

Evaluating arguments objectively.

Brilliantics illustration for “Critical Thinking”: the skill symbol over orbiting light trails on a deep blue field.

Critical thinking is not doubting everything. It is knowing that a claim and the evidence for a claim are two different objects, and asking which one you are holding.

What it is

Deliberate activation of System 2 analytical processing.

What is trained here is not a property of your character. It is a series of choices you make at specific moments — and choices, unlike character, change with practice.

What it is not

This is not being sceptical, and it is not being difficult in meetings. Rejecting things quickly is the same reflex as accepting them quickly, run backwards. What is trained here is applying the same standard to what you like and to what you do not.

Where you meet it

Three scenes where the skill is actually tested — not as an idea, but as a choice you have to make inside a few seconds.

  1. You hear one version of an incident first, and the correction never quite catches up with it.
  2. A number that suits you gets a quick look and a number that does not gets three checks.
  3. You are right, you have the numbers, and nothing moves.

How it is measured

The skill is not scored as an impression. It breaks into observable indicators, and each indicator has two ends a third party can recognise.

Evidence Evaluation

Whether you ask what was measured, on whom, and compared with what.

When it is missingThe headline number is taken as the finding, and the method behind it is not part of the reading.
When it is thereYou ask the three questions before you use the number, and say what would make it not apply here.

Bias Recognition

Whether you notice that you already had an opinion before you looked.

When it is missingThe first version you heard keeps working after the correction has arrived.
When it is thereYou write down what you heard first and who from, and say the corrected version out loud in full.

Logical Reasoning

Whether the conclusion actually follows from what you have, and not from what usually follows.

When it is missingA claim that fits the pattern is accepted at the speed the pattern is recognised.
When it is thereYou separate the claim from the evidence and say which part of the step is doing the work.

Questioning Assumptions

Whether you apply the same standard to the answer you wanted and to the one you did not.

When it is missingThe inconvenient number gets checked three times and the convenient one gets checked once.
When it is thereYou take the standard you used on the inconvenient number and run it on one you liked.

Information Synthesis

Whether you can put several sources into one position that says what it is uncertain about.

When it is missingThe sources are listed one after another, and the position is whichever one you read last.
When it is thereYou state the position, say where the sources disagree, and name the cheapest test that would settle it.

The path, level by level

  • Level 1You learn to write down the first version you heard and who you heard it from.
  • Level 2You learn to ask what was measured, on whom, and compared with what.
  • Level 3You learn to write the sentence that would make you wrong before you go looking.
  • Level 4You learn what to do when you are right and it is changing nothing.

The vocabulary

The words you pick up here are not vocabulary for show. They are handles: once a pattern has a name, it becomes something you can watch happen and interrupt.

  • the first version you heard
  • what was measured, on whom, against what
  • the sentence that would make you wrong
  • checking hard on one side only
  • the decision under the argument

Terms you learn here

The scientific basis

The base here is the study of how judgement goes wrong in regular ways. Daniel Kahneman, a psychologist who documented systematic errors in reasoning, and Keith Stanovich, who studied why intelligence and rationality are not the same measurement, both showed that the errors are shared and predictable, which is what makes them checkable.

How it is practised in Brilliantics

Lessons

  • The First Thing You Believed

    Why the first version survives the correction.

    15 min
  • Weighing the Evidence

    What a claim needs before it counts as evidence.

    20 min
  • The Opinion You Want to Keep

    Checking hard, and only on one side.

    20 min
  • Right and Ignored

    Being correct is not an argument. What to do then.

    20 min

Missions

  • Flawed Report

    A confident report lands on your desk and its conclusion is that you were right three months ago. The comparison it rests on does not hold. Nobody in the room wants to hear that, including you.

    Difficulty 3/5
  • The Viral Claim

    A forwarded post says a study proved a rule makes teams faster, and a decision is being taken on it this afternoon. You are the only person who opened the link.

    Difficulty 3/5
  • The First Version You Heard

    The internet in the flat is cut off and the first thing you hear is who forgot to pay. The real cause comes out two days later, and by then you have already treated one flatmate as the careless one.

    Difficulty 2/5
  • The Number Nobody Wants

    The club committee is buying a second hand van and your figures say it costs more than it saves. You have said so twice. You are right, and you are now the person who is against everything.

    Difficulty 4/5

Reflection prompts

  • Think of something you heard first and later found out was wrong. What did you keep doing anyway?
  • What is the last claim you repeated without checking where it came from?
  • Name an opinion you hold now. What would have to happen for you to drop it?
  • When were you last right about something and it changed nothing? What did you do next?

Sources

Every claim on this page maps to published research. The citations link to the original source.

  1. Kahneman, D. (2011). Thinking, Fast and Slow — Source on us.macmillan.com
  2. Stanovich, K. E. (2011). Rationality and the Reflective Mind — doi:10.1093/acprof:oso/9780195341140.001.0001

Frequently asked questions

What is critical thinking?

Critical thinking is not doubting everything. It is knowing that a claim and the evidence for a claim are two different objects, and asking which one you are holding.

How do I improve critical thinking?

Through practice in real situations with feedback, not through reading. The path has four levels: You learn to write down the first version you heard and who you heard it from. Then, You learn to ask what was measured, on whom, and compared with what. Then, You learn to write the sentence that would make you wrong before you go looking. Then, You learn what to do when you are right and it is changing nothing.

How is critical thinking measured?

Through 5 observable behavioural indicators — for example "Evidence Evaluation": Whether you ask what was measured, on whom, and compared with what. Scoring happens in scenarios where you choose what you would do, not in a self-assessment questionnaire.

What is critical thinking often confused with?

This is not being sceptical, and it is not being difficult in meetings. Rejecting things quickly is the same reflex as accepting them quickly, run backwards. What is trained here is applying the same standard to what you like and to what you do not.