IN THIS LESSON
When a society tears itself apart over beliefs it cannot justify, philosophy steps in to ask what it really means to know anything at all.
Topics discussed:
The 16th and 17th centuries were marked by intense religious fanaticism and violence (e.g., the Peasant Rebellion, Münster, the Thirty Years’ War).
These events pushed thinkers to demand firmer foundations for belief—not mere authority or dogma.
But agreement proved impossible: philosophers disagreed sharply about what counts as justification and what a belief must rest on to be considered rational.
Meanwhile, ancient texts and ideas—especially from Plato and the skeptics—were being rediscovered, raising old questions in a new era.
The lesson introduces epistemology, the study of knowledge, and frames the central issue: What makes a belief justified?
Plato’s Justified True Belief (JTB) theory sets the stage, but Agrippa’s Regress Argument challenges whether justification is possible at all (the setup for the next steps in the course).
Pyrrhonian skepticism reappears as a powerful alternative: suspend judgment to achieve ataraxia, tranquility free from dogmatic conflict.
Focus Questions
Why did the religious violence of the 16th–17th centuries create a demand for better standards of justification?
How does the Justified True Belief (JTB) model attempt to explain what knowledge is?
What problem does Agrippa’s Regress Argument raise for the very possibility of justified belief?
Why might rediscovered ancient ideas (e.g., Plato, Pyrrhonists) feel newly relevant to thinkers living through intellectual crisis?
Why do Pyrrhonian skeptics claim beliefs disturb us and that tranquility comes from suspending judgment?
ALEX 1.2:
The Diagnostician
Instructions to the Learner
As mentioned in the lesson, the JTB theory has been immensely influential. As far back as Plato, epistemic philosophers have been pointing out that one cannot arrive at justified true belief on accident. For example, one cannot achieve knowledge of the time by looking at a clock that is broken but just happens to be stuck at the exact time that you look at it(!). Knowledge, in other words, has to be non-lucky.
In this activity, you will work with an AI tutor to diagnose whether a person in a given scenario knows something, according to the classical JTB model.
Your goals are to:
Practice identifying the truth, belief, and justification components in real-life examples.
Explain why each component is or is not present.
Strengthen your ability to apply the JTB framework to messy everyday situations.
Receive targeted feedback on your reasoning so you can refine it — this is deliberate practice.
Here’s what will happen:
The AI will present you with a series of short belief scenarios (five total).
For each one, you will explain whether the person:
(1) has a belief
(2) the belief is true
(3) the belief is justified
(4) therefore knows (or does not know) the proposition
The AI will push back on your reasoning, point out inconsistencies, and ask follow-up questions.
After feedback, you will refine your diagnosis.
When you’re ready, copy the AI Prompt below and paste it into your AI chat.
After you finish, return to Canvas and submit your transcript + reflection.
AI Prompt
You are playing the role of a tutor, helping a student master the learning objective:
“Apply the Justified True Belief (JTB) framework to real cases and explain why a belief does or does not count as knowledge.”
Your job is to create and guide a structured activity called The Diagnostician. The activity proceeds as follows:
Present the student with a belief scenario. The scenario should be short (3–5 sentences) and about an everyday situation. The proposition at issue must actually be true in the scenario, even if the agent does not know this.
After presenting the scenario, ask the student to answer the following questions:
a. Does the person believe the proposition? Why or why not?
b. Is the proposition true?
c. Is the person justified in believing it? Why or why not?
d. Does the person know? Explain using the JTB model.
After the student answers, evaluate their reasoning.
Identify what they got right.
Challenge any unclear or incomplete reasoning.
Ask at least one follow-up question to deepen their understanding.
Require them to refine or revise their answer.
Continue this process for five scenarios, gradually increasing difficulty.
Begin with simple “lucky guess” or “weak justification” cases.
Move to cases involving conflicting evidence, misleading evidence, or accidental truths.
Ensure each case allows analysis using JTB concepts.
After all five scenarios, ask the student for a final reflection:
“What have you learned about the difference between true belief and knowledge? Which component of JTB do you find hardest to evaluate, and why?”
Keep the tone encouraging, patient, and Socratic.
Your goal is to help the student internalize how JTB works by actively applying it to real examples and revising their reasoning through deliberate practice.
More to Explore
The activities below are optional. Do them if you want more practice, deeper self-reflection, or you just like arguing with machines.
Goal
Build Agrippa’s regress argument piece by piece, so you can actually remember and reconstruct it later (instead of just recognizing it on a slide).
Instructions to the Learner
- Copy the AI Prompt below and paste it into your AI chat.
- Let the AI walk you through Agrippa’s regress argument step by step, like you’re snapping together LEGO bricks.
- You’ll practice first building the full version, then simplifying it into 2–3 “chunks” that you can easily remember.
- Save the conversation so you can review your final, chunked version of the argument later.
Optional reflection (not submitted unless assigned):
If you had to explain the regress argument in under 60 seconds to a friend,
which “chunks” would you keep and which details would you drop?
AI Prompt
I want to understand Agrippa’s Regress Argument for skepticism about knowledge.
Please guide me through an activity called “LEGO Regress Builder.”
Part 1: Build the argument, block by block.
1. Present the regress argument in its standard, step-by-step form.
Use short, clear sentences for each step, as if each step were a separate LEGO brick.
2. After presenting it, stop and ask me to:
a) Restate each step in my own words.
b) Tell you how many total “bricks” I think the argument has.
3. Give me feedback on my restatement. Correct anything important I get wrong or leave out.
Part 2: Chunk the argument.
1. Help me group the steps into 2–3 larger “chunks” that capture the core structure, for example:
- Chunk 1: Why justification is required.
- Chunk 2: The three unsatisfying options (infinite regress, circle, dogmatic stopping point).
- Chunk 3: The skeptical conclusion.
2. Ask me to write a short version of the argument using only those chunks.
3. Give me feedback and help me refine my chunked version so it’s accurate but easier to remember.
Part 3: Quick recap.
Ask me:
- Which version I find easier to remember (brick-by-brick or chunked), and why.
- To write one final, 3–4 sentence version of the regress argument from memory.
Keep the tone friendly and patient, and don’t rush me. The goal is for me to really grasp
the structure of the regress argument, not just copy text.
Goal
Connect Agrippa’s regress to something you actually know well, like social media rabbit holes, rumors, or conspiracy “evidence” chains.
Instructions to the Learner
- Think of a time when a belief was passed around (online or offline) and people kept justifying it by pointing to “what someone else said” or another video/post.
- Copy the AI Prompt below and paste it into your AI chat.
- Work with the AI to trace the chain of justification and compare it to Agrippa’s regress.
- Save the conversation if you want to look back at how the regress shows up in real life.
Optional reflection:
Did seeing the regress in a familiar context make it feel more real, or more disturbing?
AI Prompt
I want to see how Agrippa’s Regress Argument shows up in real life.
Run an activity with me called “Regress in the Wild.”
Part 1: Choose a familiar domain.
1. Ask me to choose one of these (or suggest my own):
- A TikTok or YouTube conspiracy rabbit hole,
- A rumor that spread at school or work,
- A heated political “debate” online,
- Or some other belief that kept being passed around.
2. Ask me to briefly describe what the belief was and why people said it was true.
Part 2: Trace the justification chain.
1. Help me map out how people justified the belief. For each step, ask:
- “What was the reason?”
- “What was the reason behind that reason?”
2. Keep asking “And what was the reason for that?” until:
- The chain goes in a circle,
- The chain stops at “just because,” or
- It becomes unclear or infinite.
3. Label what we found: infinite regress, circle, or dogmatic stopping point.
Part 3: Connect it to Agrippa.
1. Explain how what we just did is an example of Agrippa’s regress:
- The demand for justification,
- The three unsatisfying options,
- The skeptical worry.
2. Ask me whether, in this case, I think people really “knew” the claim, or just believed it.
Keep the tone non-judgmental and concrete. The goal is to help me
see how abstract skepticism connects to everyday belief chains.
Goal
Turn the regress argument and the JTB model into simple visuals, so you remember them not just as words but as mental diagrams.
Instructions to the Learner
- Grab a piece of paper or tablet where you can sketch.
- Copy the AI Prompt below and paste it into your AI chat.
- The AI will guide you to draw simple shapes (arrows, ladders, loops, etc.) to represent: justified true belief, infinite regress, circular justification, and dogmatic stopping points.
- You’ll then explain your drawings back to the AI in words. This strengthens memory by combining visual and verbal coding.
Optional reflection:
Which diagram “sticks” in your mind the most? Can you picture it later without looking?
AI Prompt
I want to use dual coding (visual + verbal) to understand JTB and Agrippa’s regress argument.
Guide me through an activity called “Draw the Regress.”
Part 1: Draw JTB.
1. Ask me to draw a simple diagram that represents:
- Belief (B),
- Truth (T),
- Justification (J),
and how they combine to form knowledge (K).
For example, a triangle, a Venn diagram, or four boxes with arrows.
2. After I draw it, ask me to describe my diagram in words and explain how it represents JTB.
3. Give me feedback and suggest one small improvement to make the structure clearer.
Part 2: Draw the regress options.
1. Ask me to draw:
- An infinite ladder or chain for infinite regress,
- A loop for circular justification,
- A line that just stops for dogmatic stopping points.
2. For each drawing, ask me to explain:
- What the picture shows,
- Why this kind of justification is a problem for knowledge.
Part 3: Mental rehearsal.
1. Ask me to close my eyes and imagine my diagrams.
2. Have me describe them again from memory in my own words.
3. At the end, ask me which visual is most helpful in remembering the regress argument and why.
Keep instructions concrete and simple. The goal is not artistic quality,
but creating memorable mental images linked to the concepts.
Goal
Get repeated, focused practice deciding whether a belief is justified — and why — with feedback that helps you improve over time.
Instructions to the Learner
- Copy the AI Prompt below and paste it into your AI chat.
- The AI will present a series of beliefs (starting easy, then getting harder). For each one, you’ll say whether it is: unjustified, weakly justified, or well justified — and explain your verdict.
- The AI will critique your reasoning, point out patterns in your mistakes, and give you a few follow-up cases to practice again.
- Save the conversation. You can revisit it later to see how your judgment about justification evolves.
Optional reflection:
Which kind of belief was hardest to evaluate: lucky guesses, biased beliefs, or beliefs based on expert testimony?
AI Prompt
I want deliberate practice evaluating whether beliefs are justified.
Run an activity with me called “Justification Coach.”
Part 1: Warm-up round.
1. Present me with 3 simple belief scenarios (everyday situations).
2. For each one, ask me:
a) Is the person’s belief unjustified, weakly justified, or well justified?
b) Why?
3. After each answer, tell me what you agree with and what you question.
Gently correct any major mistakes in my reasoning.
Part 2: Increase difficulty.
1. Present 5 more scenarios that involve:
- Lucky true beliefs,
- Biased evidence,
- Conflicting sources,
- Reliance on an expert,
- Or outdated information that used to be good evidence.
2. For each case, have me:
a) Classify the level of justification,
b) Explain my reasoning in a few sentences.
3. Push back with at least one follow-up question per case to make me think harder.
Part 3: Pattern spotting.
1. At the end, summarize what you noticed about my answers.
For example:
- Do I tend to be too generous or too strict about what counts as justification?
- Do I rely too much on feelings, authority, or “common sense”?
2. Ask me to write a brief reflection (3–5 sentences) on:
“What have I learned about what makes a belief justified,
and which kinds of cases are hardest for me to judge?”
Keep the tone supportive and focused on improvement.
The goal is to strengthen my judgment about justification, not to “catch me” being wrong.
The
Death of Socrates
As I mentioned in the lesson, the painting The Death of Socrates, by Jacques-Louis David, has some hidden layers of depth. Check out this video to learn about that.
Reading List
Julia Annas & Jonathan Barnes, The Modes of Scepticism.
Gordon Barnes, Applied Epistemology: An Introduction.
Roderick Beaton, The Greeks: A Global History.
Christopher Beckwith, Greek Buddha.
Richard DeWitt, Worldviews: An Introduction to the History and Philosophy of Science.
Lorraine Daston & Katharine Park, Wonders and the Order of Nature.
Thomas Kuhn, The Structure of Scientific Revolutions.