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JTB Venn Diagram - Justified True Belief

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About This MicroSim

This interactive Venn diagram illustrates the classical Justified True Belief (JTB) analysis of knowledge, one of the most important concepts in epistemology. Three overlapping circles represent the three necessary conditions for knowledge: Belief, Truth, and Justification. Knowledge exists only in the region where all three conditions overlap.

Each region of the diagram represents a different epistemic state. Hovering over any region reveals a concrete example and shows which of the three conditions are met, helping students understand why all three are necessary for knowledge.

How to Use

  1. Hover over any region of the diagram to see a pop-up explaining what that region represents, which conditions are met, and a concrete example.
  2. Switch example sets using the dropdown menu to explore Everyday, Science, or History examples.
  3. Enter Quiz Mode by clicking the "Quiz Mode" button. The sim will present an example and ask you to click the correct region on the diagram.

Key Regions Explained

  • Knowledge (center): All three conditions met — Justified True Belief
  • Belief ∩ Truth: "Lucky guess" — you believe it and it is true, but you have no justification
  • Belief ∩ Justification: "Reasonable but wrong" — justified belief that happens to be false
  • Truth ∩ Justification: "Unrecognized truth" — evidence supports the truth, but you do not believe it
  • Single circles: Only one condition is met
  • Outside all three: None of the conditions are met

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

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<iframe src="https://dmccreary.github.io/theory-of-knowledge/sims/knowledge-jtb-venn/main.html"
        height="572px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

IB Diploma Programme (Ages 16-19)

Duration

10-15 minutes

Prerequisites

  • Basic understanding of what a "knowledge claim" is
  • Familiarity with the concept that knowledge is more than just opinion

Activities

  1. Exploration (5 min): Students hover over each region to discover the seven different epistemic states. They should note why the pairwise overlaps are not knowledge.
  2. Example Switching (5 min): Students switch between Everyday, Science, and History example sets to see how the JTB framework applies across different Areas of Knowledge.
  3. Quiz Mode (5 min): Students enter Quiz Mode and try to correctly identify which region matches each example scenario.

Assessment

  • Can students explain why a "lucky guess" does not count as knowledge under the JTB analysis?
  • Can students identify which JTB condition is missing in a given scenario?
  • Can students provide their own original example for each region of the diagram?

References

  1. Justified True Belief - Wikipedia overview of the JTB analysis of knowledge
  2. Theory of Knowledge Guide - IB Diploma Programme TOK subject guide
  3. Epistemology - Stanford Encyclopedia of Philosophy