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

Reason as a source of knowledge

Both sides agree the senses give us MOST ideas. The fight is over ALL — and over whether reason alone can reach the world.

The
big
question

Can reason, without the senses, give us knowledge of the world — or is experience the only source?

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 source-of-knowledge 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.

REASON alone reaches the world · rationalismEXPERIENCE is the only source · empiricism

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

The thread that ties it together

Epistemology is one question in three sizes: what knowledge IS, where it COMES FROM (the senses, and now reason), and how FAR it reaches.

◀ Refer back · Perception as a source of knowledge
What are the immediate objects of perception?

Every view there took it for granted that the senses are A source. This unit asks if they are the ONLY one. Locke's blank slate is the same Locke.

Retrieve: Write one claim from the Perception unit that you think you know WITHOUT looking. Keep it: later it has to sit on one of Hume's prongs.
The big idea

Going left to right, reason is allowed less and less. First it proves the world. Then it only wakes ideas already there. Then it only sorts what the senses bring in. Then it is locked inside definitions. In the essay, you decide where the line falls.

Look ahead · The limits of knowledge ▶
Can philosophical scepticism be answered?

Next unit: Descartes' doubt let loose, with no God to call it back. If 'I exist' is all that survives, what else can be known?

Prime: Note which of Descartes' proofs you found weakest. The next unit asks what is left of knowledge if that proof fails.
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 9–11. See the whole year plan ↗

Lesson 1 · week 9

The map: is any knowledge innate or a priori?

Rationalism and empiricism; innatism, intuition and deduction, and Hume's fork.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 2 · week 9–10

Innatism: Plato and Leibniz against Locke

The slave boy; necessary truths; Locke's arguments against innate ideas and the innatist replies.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 3 · week 10

Intuition and deduction: the cogito

Intuition and deduction; clear and distinct ideas; the cogito and what it establishes; Russell and Hume on the 'I'.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 4 · week 11

Descartes' proofs of God and the external world

The trademark and ontological arguments, the proof of the external world, their objections and the Cartesian circle.

Lesson deck ↗ Booklet ↗ Podcast ♪
Lesson 5 · week 11

Hume's fork and the empiricist reply

Relations of ideas and matters of fact; the fork applied to Descartes and to itself; Kant's synthetic a priori; the ladder.

Lesson deck ↗ Booklet ↗ Podcast ♪
03

Four views, side by side

Where do your ideas come from? They disagree about one word: ALL. The empiricists say ALL your ideas came in through the senses — the mind started blank. The rationalists say no. Some ideas were already there at birth, and reason can build knowledge from them without looking at the world at all. The lesson teaches two rationalist claims and two empiricist replies. Claim one: some ideas are INNATE — born in us (Plato, Leibniz). Reply: the mind is a blank slate (Locke). Claim two: reason can PROVE things about the world (Descartes). Reply: reason alone only knows definitions (Hume).

Rationalism — claim one

Innatism (Plato, Leibniz)

Some ideas and truths are in the mind from birth. The senses did not put them there; reason wakes them up.
1The slave boy: never taught, only asked questions, he reaches a truth about every square. Plato: so it was in him already — remembered from before birth.
2Perfect ideas: you have never SEEN a perfect circle or perfect fairness. The senses give rough copies. The perfect idea must come from somewhere else.
3Leibniz: the senses show you one case at a time — this sunrise, this stone. They never show a MUST. But 2 + 3 MUST make 5. So the must comes from the mind.
4Leibniz's marble: innate ideas are tendencies, like veins in a block. Experience is the chisel; the shape was in the block before the first blow.
Strength It explains what the senses cannot: the MUST in maths, and perfect ideas you have never seen. Leibniz's 'tendency' answers the obvious objection that babies do not know geometry.
Weakness Locke: if an idea were innate, everyone would have it — and children do not. 'In the mind but never noticed' is either nonsense or true of everything you could ever learn. And the slave boy may only show reason at work on shapes he has seen.
Empiricism — reply one

The blank slate (Locke)

The mind starts blank. Every idea is written on it by experience — the senses, or noticing your own thoughts.
1No universal agreement: if an idea were innate, everyone would have it. Children and people with learning difficulties lack even 'a thing cannot both be and not be'.
2'Innate but not noticed' is empty. An idea you have never once been aware of is not IN your mind — or else everything you could ever learn is 'innate'.
3Two doors for ideas: sensation (the world) and reflection (your own mind at work). Simple ideas come in; the mind builds complex ones from them.
4Innate ideas are an extra we do not need. If the senses explain the idea of blue, why add 'and you were born with it'? The simplest story wins.
Strength It matches how ideas actually arrive. It explains why people disagree and why children learn slowly — things innatism struggles with. And it asks for no mystery furniture in a newborn's mind.
Weakness The missing shade: a simple idea with no impression. 'Sameness', 'cause' and 'justice' have no colour or sound to copy. And Leibniz: an innate TENDENCY does not need universal agreement — so Locke's main attack misses it.
Rationalism — claim two

Intuition & deduction (Descartes)

Reason can SEE some truths at once (intuition) and work out more from them (deduction) — knowledge of the world with no senses needed.
1The cogito: while I doubt, I cannot doubt that I am thinking. So 'I exist' is certain every time I think it. That is the first intuition.
2The trademark: I have the idea of a PERFECT being. A cause must be at least as great as its effect. I am not perfect. So only God could have put that idea in me.
3Two more proofs: I did not make myself, so something that needs no cause keeps me going; and existing is a perfection, so the perfect being must exist.
4The real world: my sensations come whether I want them or not, and I cannot correct them. A good God would not let them trick me. So matter exists.
Strength 'I exist' really does survive the hardest doubt. The method sets a standard of certainty that science still borrows. And if it works, it gives what the senses never can: knowledge of what MUST be so.
Weakness Each proof has a weak link. The causal rule is not known by reason alone (Hume). Existence is not a property (Kant). Clear ideas prove God and God proves clear ideas — a circle. And Hume: 'I exist' may only be 'thinking is happening'.
Empiricism — reply two

Hume's fork (Hume)

Reason alone can know only what words mean. Everything about the WORLD has to be learnt by looking — and is never certain.
1Impressions and ideas: an impression is what you get at the time, vivid; an idea is the faint copy you keep. Every simple idea copies a simple impression.
2The fork: relations of ideas are a priori, certain, true by definition. Matters of fact are learnt by looking, never certain, could be otherwise. There is no third prong.
3So Descartes fails. 'A cause is as great as its effect' is on neither prong. 'God' has no impression to copy. And 'I' is never found inside — only a bundle of thoughts.
4Reason's real job is to trace links between ideas the senses gave. A book that claims to know the world by reason alone: throw it in the fire.
Strength It gives rationalism its best case — maths — and still denies it the world. One test knocks down every one of Descartes' proofs. And it leaves a clear rule that any claim must pass.
Weakness The fork fails its own test: it is neither true by definition nor learnt by looking. The cogito looks like a third kind — not true by definition, yet certain. And if 'every event has a cause' fits neither prong, science goes in the fire too.
04

Six ideas — where did each one come from?

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 slave boy next to the paint chart. One is meant to show an idea was BORN in you; the other shows an idea that was NOT copied from the senses. Say what the two cases have in common.
Challenge
“The weakest step is … because …”
“That only follows if … — and it might not.”
This unit · Take Hume's fire. A book says: 'Every event has a cause.' Which prong? If neither, does the book burn — or does Hume's rule? Say which, and why.
Weigh
“Even granting …, … — so on balance …”
“The cost of that reply is …”
This unit · Grant Leibniz that seeing cases never gives you a MUST. Does that show 2 + 3 = 5 was born in you — or only that reason can see it? Say what hangs on the difference.
Reason from cases
“In case A …; in B …; so in general …”
“The case that breaks the pattern is …”
This unit · Go through the six ideas on the slide. For each one say: the senses, reason, or born with it? Say the rule you are using. Then find the idea that is hardest to place.
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 'a priori knowledge'?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. Justified independently of experience
  2. One example
  3. Contrast with a posteriori in half a sentence.
Write it — about 2 lines
0 words · nothing here is saved — copy it into your book
Q025 marks · Outline
Outline Hume's fork.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. Both prongs named
  2. For each: how known, necessary or contingent, an example
  3. The claim that there is no third kind.
Write it — about 4 lines
0 words · nothing here is saved — copy it into your book
Q035 marks · Explain
Explain Locke's argument against innate ideas from universal assent.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. Premise: innate ideas would command universal assent
  2. Premise: none does (children, the impaired)
  3. Conclusion
  4. The 'innate but unknown' reply and why Locke rejects it.
Write it — about 5 lines
0 words · nothing here is saved — copy it into your book
Q0412 marks · Explain
Explain Descartes' trademark argument and one criticism of 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 idea of God
  2. The causal adequacy principle
  3. Why only God suffices
  4. The criticism (Hume on the causal principle, or 'we construct the idea by negation')
  5. What Descartes would reply.
Write it — about 8 lines
0 words · nothing here is saved — copy it into your book
Q0525 marks · Evaluate
Can reason alone give us knowledge of the world?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. Descartes' strongest deduction tested by Hume
  3. Innatism tested by Locke
  4. The fork tested on itself
  5. Judgement that names what the losing side 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: Find a claim that is a priori, necessary, AND tells you something about the world that no definition contains. If you can, Hume's fork has a third prong. If you cannot, say why every candidate fails.
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 reason alone give us knowledge of the world?' — thesis, one idea run through every view, 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 saying what each view claims, clearly. AO2 is running ONE idea through all of them and reaching a judgement. Never judge a view you have not first stated.
09

Watch

Rationalism (A level) — watch for rationalism and empiricism as rival accounts of the source of knowledge — Fliggosophy, 24:35

▶Rationalism (A level) · 24 min
Watch for: rationalism and empiricism as rival accounts of the source of knowledge — Fliggosophy, 24:35↗▶Intuition and deduction · 18 min
Watch for: intuition and deduction — the rationalist's method — Sally Latham, 18:07↗▶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 Hume's fork in one sentence.
  2. Say Locke's 'everyone would have it' argument — and Leibniz's reply.
  3. Give one strength AND one weakness of Descartes' proof of God from the idea of God.

Challenge

Argue: Which view would you defend in a 25-mark answer — and which ONE idea (cause, God or self) would you use to test all four?

AO1 vs AO2 AO1 is saying what each view claims, clearly. AO2 is running ONE idea through all of them and reaching a judgement. Never judge a view you have not first stated.