A-LEVEL PHILOSOPHY · AQA 7172 · PAPER 1Harlington School · Philosophy · Epistemology

The limits of knowledge

The sceptic's rule: cannot rule it out = do not know. Every response attacks that rule, or tries to meet it.

The
big
question

Can philosophical scepticism about the external world be answered — and if not, how much do we know?

How it is examined: five questions — 3 · 5 · 5 · 12 · 25 marks. The Year 12 December test is Q01–Q04; the 25-mark essay is the Year 13 stretch. This unit's ladder ↓
02

The response line

The unit's positions, lined up. Tap a position to see what it claims and where it is strong or weak. If you can order them, you understand them.

The sceptic must be BEATEN · certainty won backThe sceptic can be SIDESTEPPED · knowledge without proof

Tap a circle — or use Tab and Enter — to explore each position.

The thread that ties it together

Epistemology ran on one question in three sizes: what knowledge is, where it comes from, and — now — how far it reaches. The brain in a vat is the test case for all three.

◀ Refer back · Reason as a source of knowledge
Can reason alone give us knowledge of the world?

Last unit: Descartes used doubt to find a certain start — the cogito. Today the doubt runs free. If his proofs of God fail, he has no answer to it.

Retrieve: Write the Cartesian circle in two sentences: 'I trust clear ideas because…' and 'I know God exists because…'. Today decides if it can be broken.
The big idea

Going left to right, each response asks less of knowledge: first certainty, then a world that just IS experience, then good evidence, then only a process that works. In the essay you decide how much can be given up before 'knowledge' has been given up too.

Look ahead · Moral Philosophy — normative ethics ▶
What makes an action right?

Epistemology asked what we can know. Moral philosophy asks what we should do — and whether THAT can be known comes back in meta-ethics.

Prime: Write one moral claim you are sure of. Ask: is it certain the way 'I exist' is, or the way 'I have hands' is?
01

The lessons in this unit

5 lessons, taught in this order. The first is the map of the whole unit — this page mirrors it — and each lesson after it takes one part deeper. Timetabled for Track A · Autumn 2 · weeks 12–14. See the whole year plan ↗

Lesson 1 · week 12

The map: can we know anything at all?

Scepticism, the three waves, and the four families of response.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 2 · week 12

Philosophical scepticism and the three waves

Normal incredulity vs philosophical scepticism; illusion, dreaming, the demon; local vs global.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 3 · week 13

Descartes' own response

The cogito, clear and distinct ideas, God as guarantor — and the Cartesian circle.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 4 · week 13–14

Empiricist responses: Locke, Berkeley, Russell

Best hypothesis, the involuntariness of perception, idealism's dissolution of the problem.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 5 · week 14

Reliabilism as a response; the December test

Knowing without proving you know; Q01–Q04 practice; the ladder.

Lesson deck ↗ Booklet ↗ Podcast ♪
03

Four responses, side by side

What makes a doubt philosophical? But the sceptic says good evidence is not enough. Name one possibility you cannot rule out — a dream, a demon, a brain in a tank. If it were true, your belief would be false. You cannot rule it out. So, the sceptic says, you do not KNOW. Four responses, four routes. Two drop the sceptic's demand: REPLY (good evidence is enough — Locke, Russell) and SIDESTEP (a reliable process is enough — reliabilism). Two keep it: REFUTE (prove the demon away — Descartes) and DISSOLVE (there is no hidden world to doubt — Berkeley).

Route one

Reply: good evidence is enough

We cannot prove the world is there. But everything we experience says it is — and that is enough.
1Locke — you cannot choose what you see when you open your eyes. Something outside you is making you see it.
2Locke — your senses agree. You see the apple, feel it, taste it. Each sense homed in on one real thing.
3Russell — a real world is the best explanation. It explains the rotten apple; the no-world story explains nothing.
4So drop the demand for proof. Knowledge needs good evidence, not the ruling-out of every possibility.
Strength It is how knowledge really works. No science proves its results beyond every possible doubt, and nobody says science knows nothing. It answers the sceptic without pretending the demon is impossible.
Weakness All the evidence — the rot, the agreement of the senses, the sights you cannot control — is EXPERIENCE. A demon would produce the same experience. So the evidence fits both stories. And 'simpler' is not the same as 'true'.
Route two

Sidestep: a reliable process is enough

You know if your belief came from a process that works. Proving the sceptic wrong was never required.
1Knowledge = a true belief from a reliable process. If my eyes work, I know there is a table — whether or not I can prove I am not in a vat.
2The sceptic's demand is too strong. 'You cannot rule out the demon' shows only that I cannot PROVE I know — not that I do not know.
3Externalism: what makes a belief knowledge can be a fact outside your head (the process works) that you cannot check from inside.
4So the sceptic is not beaten but bypassed. If the world is normal, we know. If the demon is real, we do not. The sceptic has not shown which.
Strength It explains how children, animals and ordinary people know things without ever answering a sceptic. And it exposes the sceptic's hidden assumption: that to know, you must first know that you know.
Weakness It cannot tell you whether you know. If the demon is real, every 'reliable' process is a fake, and you could never find out. The sceptic asked 'do you know?' and reliabilism answers 'you might'. That is not an answer.
The head-on route

Refute: Descartes' own response

Doubt everything. Find the one thing that cannot be doubted. Rebuild knowledge from it by reason alone.
1The cogito survives the demon: I cannot doubt that I am thinking, so 'I exist' is certain every time I think it.
2Clear and distinct ideas: whatever I see as clearly as the cogito, I take to be true. That is his mark of truth.
3God: the trademark and ontological arguments prove a perfect being exists. A perfect being does not deceive.
4The world: my sensations come unwilled, and a good God would not let them mislead me. So things outside me exist.
Strength He meets the sceptic on his own ground and wins the first move. The cogito really is safe from the demon. If the proofs of God work, everything the sceptic took is handed back — with a guarantee.
Weakness The circle. Clear ideas are trusted because God exists; God is proved by clear ideas. Break the circle and nothing beyond 'I exist' survives. The demon wins by default.
The challenge

Dissolve: Berkeley's response

There is no world behind your experience to doubt. Your experience IS the world.
1The sceptic needs a gap: the ideas in your mind on one side, a hidden world on the other, which might not match.
2Idealism closes the gap. To be is to be perceived. The table IS the ideas. There is nothing further to be wrong about.
3Order and continuity come from God, who perceives everything always. The world does not blink out when you look away.
4So the demon has no job. Every experience it could fake is, on this view, simply real. Doubt about the outside world has nothing to be about.
Strength It is the only response that leaves the sceptic NOTHING: no veil, no gap, no hidden world that might differ from how it looks. It takes the sceptic's argument seriously and turns it into a proof of idealism.
Weakness It wins by giving up the world. Most people would rather keep the world and the doubt. And God carries everything: remove him and order, continuity and the dream/real line are gone — scepticism by another door.
04

Six doubts — everyday, or philosophical?

Every position in this unit is tested on cases. Read each one, decide what you would say, then tap for the question the examiners would ask.

05

Talk it through — four moves

Say it before you write it. Four moves, with the sentence stems the examiners are listening for in your essay — connect, challenge, weigh, reason from cases.

Connect
“This connects to … because …”
“That is the same move as … made in …”
This unit · Put the rotten apple next to the mushrooms. Both say: no proof, still knowledge. Say what is DIFFERENT: what does each one need — reasons you can give, or a process that works?
Challenge
“The weakest step is … because …”
“That only follows if … — and it might not.”
This unit · Take the rotten apple. Berkeley says: all that evidence is experience, and a demon would give you the same. Is that fatal — or just a demand for proof that Russell already refused?
Weigh
“Even granting …, … — so on balance …”
“The cost of that reply is …”
This unit · Each response gives something up: certainty (Locke, Russell), the world (Berkeley), or being able to say 'I know' (reliabilism). Which costs least? Say why.
Reason from cases
“In case A …; in B …; so in general …”
“The case that breaks the pattern is …”
This unit · Go through the six doubts. For each one say: can evidence settle it, or not? Say the rule you have found. Then test it on 'the sun will rise tomorrow'.
Protocol Pairs 2 min → fours 3 min → two speakers to the front. Roles: Proposer · Challenger · Judge · Reporter. Rule: every reply begins by restating what you heard. · 8 min
06

The exam ladder — this unit's mock

Five rungs, one per question type. Open a rung for the shape a full answer takes and this unit's plan, then write. Everyone climbs Q01–Q04; Q05 is the stretch.

Q013 marks · Define
What is meant by 'global scepticism'?SHAPE One precise sentence a philosopher would accept
The shape of a full answer
  1. One precise sentence
  2. A contrast or example if it earns clarity
  3. No evaluation, no history — stop
Your plan — this unit
  1. Doubt about whether knowledge is possible at all, not in one domain
  2. Contrast with local scepticism in half a sentence.
Write it — about 2 lines
0 words · nothing here is saved — copy it into your book
Q025 marks · Outline
Outline the difference between philosophical scepticism and normal incredulity.SHAPE Every part the specification names, in order
The shape of a full answer
  1. State the view or distinction in full
  2. Use the technical vocabulary exactly
  3. Order it: claim → the parts → what follows
Your plan — this unit
  1. Normal: about a claim, sensitive to evidence, settled by it. Philosophical: about the source, built on a possibility that cannot be excluded, not settled by evidence. One example of each.
Write it — about 4 lines
0 words · nothing here is saved — copy it into your book
Q035 marks · Explain
Explain Descartes' evil demon argument.SHAPE Set-up → premises → conclusion
The shape of a full answer
  1. Set-up: name the target — which view, which claim
  2. Premises: state them in order, numbered
  3. Conclusion: show it follows, and what it costs
Your plan — this unit
  1. The supposition
  2. Why it reaches even mathematics
  3. The sceptical conclusion
  4. What it leaves standing.
Write it — about 5 lines
0 words · nothing here is saved — copy it into your book
Q0412 marks · Explain
Explain Russell's response to scepticism about the external world and one issue with it.SHAPE Two linked explanations, both full
The shape of a full answer
  1. Part A: the view or argument, in full
  2. Part B: the issue or reply, with its own premises and conclusion
  3. The link: one sentence on what B does to A
  4. Mostly AO1 — explain, do not judge; the verdict waits for the essay
Your plan — this unit
  1. The best-hypothesis argument (order, simplicity, instinctive belief)
  2. The concession about proof
  3. The issue — all evidence is experience, so it cannot decide between hypotheses.
Write it — about 8 lines
0 words · nothing here is saved — copy it into your book
Q0525 marks · Evaluate
Can philosophical scepticism about the external world be answered?SHAPE A sustained argument to a judgement
The shape of a full answer
  1. Introduction: define the term, state your thesis, name the positions you will test
  2. Each paragraph: state the argument · test it with the strongest objection · reply · WEIGH
  3. One shared case, run through every position
  4. Judgement: what survives, and what the losing views cannot explain
Your plan — this unit
  1. Thesis
  2. The demon stated
  3. Descartes tested on the circle
  4. One empiricist and one other response tested on the vat
  5. Judgement naming what each concedes and what the losers cannot explain.
Write it — about 10 lines to plan, then the essay in your book
0 words · nothing here is saved — copy it into your book
Beyond the ladder: Build the strongest sceptical argument you can that does NOT use the senses, dreaming or a deceiver. Then ask which of the four responses touches it.
07

Your resources

Everything for the unit, in one place. The lesson, the booklet and the podcast belong to this unit; the Epistemology Companion runs across the whole series.

Teacher setup: links aren't set yet. Open this file, find the LINKS list near the bottom, and paste each SharePoint share link once. Buttons with no link show as "Link not set".
✓Revise & mock — per lesson: the episode, three games, and every past-paper question with the shape of a full answer↗🎮The Arena — six games on the words, positions, arguments and verdicts of this unit: Bronze, Silver, Gold; objective and evaluative tracks↗✓Your Companion — tick what you understand, see what you have done in the Arena, place yourself and choose your next move; print it for your teacher↗▲Intervention — E–D to C, C to B, B to A*: the four moves for your tier, with drills, model answers at every level and Coach Owl↗ ▣Lesson deck — the slides, with the four positions, the cases and the ladder↗ ✎Completion booklet — greyscale, mirrors the lesson — fill it as you go↗ ♪Lesson podcast — a teacher and a student argue the unit through to a judgement↗ ≡Podcast transcript — read along, or read instead↗ 🦉Epistemology Companion — checklist, key words, review workbook and the Q01–Q05 planner↗ ♪Overview podcast — the whole series as one argument (team teach)↗ ◎NotebookLM pack — make your own podcast from the unit's sources↗ ▤Printable flashcards — fold-over cards to cut out↗ ▶Revision playlist — the YouTube playlist for the course↗
08

How to revise this unit

Use the resources in this order. The Epistemology Companion is where you learn to plan all five question types.

Listen to the podcast, then read the transcript

A teacher and a student argue every position through to a judgement. Pause at each position and say what it claims before they do.

Complete the booklet

Given text on the left, your words on the right. Decide the strength and the weakness YOU would give each position.

Flip the flashcards until every term is one sentence

Key terms first, then the positions. A term you cannot define in one sentence is a Q01 you cannot yet answer.

Climb the ladder: Q01 to Q04 from a plan

Precision questions. Open each rung, plan from the shape, write, then check every part the specification names is there.

Plan Q05 with one shared case

In the Companion: Part 4, the Q05 planning frame. Plan 'Can philosophical scepticism be answered?' — thesis, the vat run through every response, judgement.

Q01–Q04 · 3, 5, 5 and 12 marks · precision
Q01 Define — one precise sentence a philosopher would accept. No evaluation, no history.
Q02 Outline — every part the specification names, in order, in the technical vocabulary.
Q03 Explain — set-up, premises in order, conclusion — and what it costs the target.
Q04 Explain … and … — two full explanations and the one sentence that links them. Still AO1: explain, do not judge.
Q05 · 25 marks · AO2 is 20 of them
What it is — a sustained argument to a judgement. Every paragraph states an argument, tests it, replies, and WEIGHS.
Aim — AO1 is telling each response clearly and saying what it gives up. AO2 is running ONE case — the vat — through all of them and reaching a judgement. Never judge a response you have not first explained.
09

Watch

Limits of knowledge (AQA) — watch for the unit in one video — scepticism and the responses — Sally Latham, 19:32

▶Limits of knowledge (AQA) · 19 min
Watch for: the unit in one video — scepticism and the responses — Sally Latham, 19:32↗▶Scepticism (A level) · 22 min
Watch for: philosophical scepticism, local and global — Fliggosophy, 22:46↗▶The course playlist (AQA)
Watch for: the whole course, episode by episode; use it when a lesson's own videos are not enough.↗
10

Flashcards — test yourself

Flip a card to check yourself. Switch between key terms (term → meaning) and positions (position → claim, strength & weakness).

Tap any card to flip ·
11

Exit ticket

Three things to recall, one to argue. Answer them in your book before you leave the unit.

Recall

  1. Say the difference between everyday doubt and philosophical doubt in one sentence.
  2. Name Descartes' three waves. What survives the third?
  3. Give one strength AND one weakness of reliabilism as an answer to the sceptic.

Challenge

Argue: Which response would you defend in a 25-mark answer — and what would you have to give up to the sceptic to do it?

AO1 vs AO2 AO1 is telling each response clearly and saying what it gives up. AO2 is running ONE case — the vat — through all of them and reaching a judgement. Never judge a response you have not first explained.