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v0.1.1489
NotesPhilosophyTopic 3.1Sources of knowledge
Back to Philosophy Topics
3.1.42 min read

Sources of knowledge

IB Philosophy • Unit 3

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Contents

  • How do you actually know what you know?
  • Testimony — can being TOLD be knowing?
  • A fourth source: the flash of insight
The big idea: Think of ten things you're sure of. That the Earth orbits the Sun. That a place called Antarctica exists. That you were born on a certain date.

Now ask: how many did you work out yourself — and how many were you simply told? Almost all of it, you were told. This micro looks at the sources knowledge really comes from.

We can name three main sources of knowledge: perception, reason and testimony.

Three sources of knowledge

1

Perception

What you learn directly through your senses — seeing, hearing, touching.

2

Reason

What you work out by thinking — logic, maths, drawing conclusions.

3

Testimony

What others tell you — teachers, books, news, the whole store of human knowledge.

See · Think · Told

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Testimony is the giant of the three — and also the one philosophers most distrust.

Most of what you 'know', you never checked: You've never been to Antarctica, never measured the Earth's orbit, never checked your own birth certificate against the hospital. You believe these because trustworthy people told you. That's testimony — and it's the source almost all your knowledge actually runs through.
Checkpoint — testimony: In one line: most of what you know you were TOLD, and that can be real knowledge — as long as the source is reliable. Now a fourth, more surprising source.

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Perception, reason and testimony are the usual three. One Indian tradition adds a fourth that doesn't fit any of them.

Bhartrhari: pratibha, a flash of knowing: The Indian philosopher Bhartrhari wrote about pratibha — a sudden, whole understanding that arrives all at once, not by step-by-step reasoning or by looking. It's the 'aha!' when a sentence's meaning lands, or when a solution simply appears. You didn't deduce it and no one told you; it came as a flash of intuition. Bhartrhari treated this immediate insight as a genuine way of knowing in its own right.
Go further — higher-level insight: Notice how pratibha pressures the JTB definition from 3.1.1. Insight can be true and it can be belief — but can you give the JUSTIFICATION? 'I just saw it' isn't a reason you can spell out. So intuition either widens what counts as justification, or sits awkwardly outside knowledge. Naming that tension is a top-band move.
Checkpoint — pratibha: In one line: pratibha is a flash of intuitive insight — knowing something all at once, without deducing it or being told.

IB Exam Questions on Sources of knowledge

Practice with IB-style questions filtered to Topic 3.1.4. Get instant AI feedback on every answer.

Practice Topic 3.1.4 QuestionsBrowse All Philosophy Topics

How Sources of knowledge Appears in IB Exams

Examiners use specific command terms when asking about this topic. Here's what to expect:

Define

Give the precise meaning of key terms related to Sources of knowledge.

AO1
Describe

Give a detailed account of processes or features in Sources of knowledge.

AO2
Explain

Give reasons WHY — cause and effect within Sources of knowledge.

AO3
Evaluate

Weigh strengths AND limitations of approaches in Sources of knowledge.

AO3
Discuss

Present arguments FOR and AGAINST with a balanced conclusion.

AO3

See the full IB Command Terms guide →

Related Philosophy Topics

Continue learning with these related topics from the same unit:

3.1.1What is knowledge?
3.1.2Truth
3.1.3Rationalism vs empiricism
3.1.5Reasoning and self-knowledge
View all Philosophy topics

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3.1.3Rationalism vs empiricism
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13 practice questions on Sources of knowledge

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