AQA A-Level Philosophy (7172)

## Learning Outcomes

- Understand the central question in perception: what are the immediate objects of perception?
- Identify the main claims of direct realism, indirect realism, and Berkeley’s idealism
- Explain the arguments from illusion, perceptual variation, hallucination, and time-lag
- Distinguish clearly between mind-independent objects, sense-data, and mind-dependent ideas
- Assess Locke’s primary and secondary quality distinction and Berkeley’s objections to it
- Evaluate the strengths and weaknesses of each theory in AQA-style exam answers

## AQA A-Level Philosophy (7172) Syllabus

For the AQA A-Level Philosophy (7172), you are expected to understand perception as a source of knowledge, with a focus on the following syllabus points:

- Know that **direct realism** claims the immediate objects of perception are mind-independent objects and their properties
- Identify the challenges to direct realism from illusion, perceptual variation, hallucination, and the time-lag argument
- Understand that **indirect realism** claims the immediate objects of perception are mind-dependent **sense-data** caused by and representing mind-independent objects
- Explain Locke’s distinction between **primary qualities** and **secondary qualities**
- Understand responses to scepticism within indirect realism, including the involuntary nature of experience, the coherence of the senses, and the external world as the best hypothesis
- Explain Berkeley’s objection that mind-dependent ideas cannot be like mind-independent objects
- Know that **Berkeley’s idealism** denies mind-independent material substance and holds that ordinary objects are mind-dependent
- Assess Berkeley’s attack on the primary/secondary quality distinction, the **Master Argument**, and the problems of illusion, hallucination, solipsism, and God

## Test Your Knowledge

_Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision._

1. What does each theory of perception say the immediate objects of perception are?
2. How does the argument from hallucination challenge direct realism?
3. What is the difference between illusion and hallucination?
4. How does Locke use the distinction between primary and secondary qualities?
5. Why does Berkeley think the idea of mind-independent matter is incoherent?

## Introduction

Perception matters in epistemology because much of what we claim to know seems to come through the senses. I know there is a table in front of me, that the window is open, or that the sky is dark because I can see, hear, or feel these things. But philosophy asks a deeper question: when I perceive, what exactly am I directly aware of?

That question drives the whole topic. If perception gives direct access to reality, then knowledge of the external world looks secure. If perception only gives access to inner appearances, then scepticism becomes much harder to resist. The debate turns on what the immediate objects of perception are and whether perception connects us to a mind-independent world.

> **Key Term: perception**
> Awareness of the world through the senses.

### Direct realism and the case for direct access

**Direct realism**, often called **naive realism**, says that in normal perception the immediate objects of perception are ordinary, mind-independent physical objects and their properties. When you see a red apple, what you are directly aware of is the apple itself, not a mental image, not a sense-datum, and not an inner representation.

> **Key Term: direct realism**
> The view that the immediate objects of perception are mind-independent objects and their properties.

This view is attractive because it matches common sense. In everyday life, perception seems outward-facing. You look at a tree and it seems that you are aware of the tree. You do not seem to inspect a private inner item and then infer a tree from it. Direct realism also avoids a major sceptical worry. If perception puts you in direct contact with the world, there is no gap between mind and world that must later be bridged.

However, AQA requires you to know the standard objections.

The **argument from illusion** points out that real objects can appear other than they are. A straight stick in water looks bent. If perception were always direct awareness of the object as it is, how could this happen? The indirect realist argues that what is immediately perceived must be something mental: an appearance or sense-datum.

The **argument from perceptual variation** develops the same point. The same object can look different from different positions or in different conditions. A white wall may look yellow in dim light. A round coin may look elliptical from an angle. If the object itself has not changed, but what is immediately perceived has changed, then the immediate object may not be the public object itself.

> **Key Term: perceptual variation**
> Cases where the same object appears differently to observers or under different conditions.

The **argument from hallucination** is more serious. In an illusion there is a real object present, though it is misperceived. In a hallucination there may be no corresponding external object at all, yet the experience can feel just like perception. If a hallucination can be subjectively indistinguishable from genuine perception, then direct realists must explain how one experience can involve direct awareness of a physical object while the other does not.

> **Key Term: hallucination**
> A perception-like experience in which there is no corresponding external object.

The **time-lag argument** says perception is not instantaneous. Light and sound take time to travel. When you see a distant star, the star may already have changed or even ceased to exist. This raises a key question: if there is always a delay, are you really directly aware of the object itself as it is now?

A strong direct realist reply is that these objections show that perception can go wrong, not that all perception is indirect. In illusion and variation, the realist can say the same object is still being perceived, even though it appears different because of conditions, perspective, or the medium. Looking bent is not the same as being bent. The object remains the object of perception, even if judgement about it is mistaken.

The hallucination case is harder. A common reply is **disjunctivism**: veridical perception and hallucination are fundamentally different kinds of mental state, even if they feel the same from the inside. The hallucinating subject is not perceiving an inner common object shared with the veridical perceiver. This matters because the anti-direct realist argument often assumes a common factor between the two experiences.

> **Key Term: disjunctivism**
> The view that veridical perception and hallucination are different kinds of mental state, rather than sharing the same immediate object.

Direct realists can also reply to time-lag by distinguishing causal mediation from epistemic indirectness. Yes, light causally mediates perception. But it does not follow that there must be a mind-dependent object standing between perceiver and world. A delay in the causal chain is not yet proof of an inner intermediary.

> **Test Tip:** In a 12-mark answer, do not just list the four objections to direct realism. Explain how each objection is meant to move from changing appearances to the conclusion that the immediate object is not mind-independent.

### Indirect realism, Locke, and the veil of perception

**Indirect realism**, also called **representative realism**, agrees that a mind-independent world exists. In that sense it is still realist. But it denies that we perceive that world directly. Instead, the immediate objects of perception are mind-dependent ideas or **sense-data**, caused by external objects and representing them.

> **Key Term: indirect realism**
> The view that the immediate objects of perception are mind-dependent objects that are caused by and represent mind-independent objects.
>
> **Key Term: sense-data**
> Mind-dependent items immediately present to the mind in perception.

The structure is simple:

external object -> causes sense-datum or idea -> the mind is directly aware of that sense-datum

This view explains illusion, variation, and hallucination more neatly than direct realism. If what you directly experience is a mind-dependent appearance, then it is no surprise that the appearance may differ from the object, vary by viewpoint, or even occur without any object at all.

John Locke is the key named philosopher here. His account relies on the distinction between **primary qualities** and **secondary qualities**.

> **Key Term: primary qualities**
> Qualities said to exist in objects themselves, such as shape, size, motion, number, and solidity.
>
> **Key Term: secondary qualities**
> Qualities that are powers in objects to produce sensations in us, such as colour, taste, smell, and sound.

Locke’s idea is that some features belong to objects as they are in themselves. A ball really is spherical, extended, and in motion or at rest. These are primary qualities. But colour, taste, smell, and sound are not in objects in the same way. Instead, the object has powers to produce these sensations in perceivers. A chilli is not literally “hot” in the way it is extended. Rather, its physical structure causes a certain burning sensation in us.

This distinction helps indirect realism because it explains why some aspects of experience seem mind-dependent. The tomato’s redness can vary with lighting and perceivers, but its shape and size seem more stable.

Indirect realism has another strength: it explains why we are sometimes wrong. In illusion, the sense-datum does not accurately represent the object. In hallucination, there is a perception-like state without a corresponding object. In veridical perception, the sense-datum is caused in the normal way by an external object.

But this success creates the theory’s biggest weakness: the **veil of perception**. If we are directly aware only of sense-data, how can we know that mind-independent objects exist at all? And even if they do, how can we know our ideas resemble them?

> **Key Term: veil of perception**
> The problem that if we directly perceive only inner representations, knowledge of the external world becomes uncertain.

This is a sceptical problem because all evidence about the world now comes through intermediaries. Suppose all I ever experience are private sense-data. I cannot step outside them and compare them with the external object to check accuracy. The representative relation is claimed, but never directly verified.

Indirect realists offer several responses. Locke points to the **involuntary nature of experience**. I cannot simply choose to see a blazing fire in front of me by willing it. Perceptions force themselves upon me in a way imagination does not. That suggests an external cause.

A second reply is the **coherence of the senses**. My different senses fit together in regular ways. I see the fire, hear crackling, feel heat, and smell smoke. These experiences support one another and form a stable pattern. That coherence is easier to explain if one external object is causing them.

A third reply, linked with Bertrand Russell, is that the external world is the **best hypothesis**. The existence of physical objects explains the order, continuity, and predictability of experience better than the alternatives. If I leave an apple in a drawer and later find it rotten, the physical world hypothesis explains why my later experiences are structured as they are.

These replies make indirect realism more reasonable, but they do not remove the central difficulty. They show that belief in an external world is plausible, not that it is certain. That matters in evaluation. Indirect realism explains perceptual error well, but it seems to purchase that advantage at the cost of scepticism.

> **Test Tip:** A common exam mistake is to confuse indirect realism with idealism. Indirect realists still believe in mind-independent matter. Berkeley does not.

### Berkeley’s idealism: attack, Master Argument, and problems

Berkeley accepts the basic starting point that what we immediately perceive are ideas. But he rejects Locke’s further claim that these ideas are caused by and represent mind-independent material substance. Berkeley argues that matter is an unnecessary and incoherent addition. Only minds and ideas exist.

> **Key Term: Berkeley’s idealism**
> The view that the immediate objects of perception are mind-dependent ideas and that there are no mind-independent material objects.

His slogan is **esse est percipi**: to be is to be perceived. A table is not a material thing standing behind experience. It is a collection or bundle of ideas: colour, shape, hardness, position, and so on, as perceived by minds.

> **Key Term: esse est percipi**
> Berkeley’s claim that the existence of sensible objects consists in their being perceived.

Berkeley first attacks Locke’s primary/secondary quality distinction. Locke says secondary qualities are mind-dependent, but primary qualities belong to objects themselves. Berkeley argues this split fails because primary qualities also vary with perspective. A tower looks small from a distance and large from nearby. A coin looks circular from above and elliptical from an angle. If variation shows colour is mind-dependent, why does it not also show shape and size are mind-dependent? Berkeley’s point is that Locke cannot keep primary qualities safely on the object while moving secondary qualities into the mind.

Berkeley also uses the **likeness principle**: an idea can only be like another idea. A mental item cannot resemble a non-mental, mind-independent material object. If indirect realism says ideas represent matter, Berkeley asks: how could we even make sense of resemblance between two utterly different kinds of thing?

> **Key Term: likeness principle**
> Berkeley’s claim that an idea can only resemble another idea, not a mind-independent material object.

This leads to the **Master Argument**. Try to conceive of a tree existing unperceived. Berkeley says that as soon as you conceive it, it is in a mind, namely yours. So you have not conceived an unconceived object at all. He concludes that the very idea of a mind-independent sensible object is contradictory.

> **Key Term: Master Argument**
> Berkeley’s argument that one cannot conceive of an unconceived object, because conceiving it places it in a mind.

Why is this attractive? It removes the veil of perception. If reality is made of ideas directly perceived by minds, then there is no hidden material world behind appearances. The gap between appearance and reality is collapsed.

However, Berkeley faces serious problems.

First, illusion and hallucination. If all that exists are ideas, how do we distinguish veridical perception from error? Berkeley replies that the error does not lie in the immediate perception itself. When the stick looks bent in water, that visual idea is real as an idea. The mistake comes when I infer that it will feel bent or continue to look bent in other conditions. He also says real perceptions are more vivid, orderly, and coherent than imagination, dreams, or hallucinations.

This helps, but critics still think idealism makes perceptual error too hard to explain. Direct and indirect realists can say a perception is wrong because it fails to match a mind-independent object. Berkeley cannot use that move.

Second, idealism seems to risk **solipsism**, the view that only one’s own mind exists. If objects are mind-dependent, do tables disappear when I leave the room? Did the world only begin when I was born?

> **Key Term: solipsism**
> The view that only one’s own mind is known or exists.

Berkeley’s answer is God. Objects continue to exist because they are always perceived by an infinite divine mind. God also explains why our experiences are regular, ordered, and involuntary.

Yet this raises another problem. Berkeley uses God to save common sense, but the move can look ad hoc: a theoretical rescue added because idealism would otherwise collapse into absurdity. There is also a tension in Berkeley’s own account. If we only have ideas, and minds are not themselves ideas, then how do we know other minds, including God’s, exist?

The deepest criticism of the Master Argument is that it confuses a claim about conceiving with a claim about existing. From the fact that I cannot think of a tree without thinking of it, it does not follow that the tree itself depends on being thought. The argument may show a limit in how we represent mind-independent things, not a limit on what can exist.

### How to structure an evaluative answer

For a **25-mark** question on perception, build the essay around the question of what the immediate objects of perception are. That gives your answer a clear spine.

Start with a short paragraph setting out the theory accurately. Then test it against the strongest objections. For direct realism, that usually means hallucination and time-lag. For indirect realism, focus on scepticism and Berkeley’s likeness point. For Berkeley, focus on the Master Argument, illusion, solipsism, and God.

Do not evaluate in vague terms like “this is convincing” or “this is weak.” Explain why. For example: indirect realism explains perceptual error better because sense-data give a clear account of misleading appearances; however, this advantage creates the veil of perception and makes knowledge of the external world inferential rather than direct.

A strong judgement often uses a contrast. Direct realism preserves common sense but struggles with hallucination. Indirect realism explains error but risks scepticism. Berkeley removes scepticism about matter by denying matter, but many think this solution is too costly because it depends on controversial arguments and God.

> **Test Tip:** In 25-mark essays, comparison is often the key to AO2. Do not evaluate each theory in isolation. Show why a strength of one theory often mirrors a weakness in another.

## Key Point Checklist

_This article has covered the following key knowledge points:_

- Perception raises the question of what the immediate objects of perception are
- Direct realism says we directly perceive mind-independent objects and their properties
- The main objections to direct realism are illusion, perceptual variation, hallucination, and time-lag
- Hallucination is a strong challenge because there may be no external object despite an apparently perceptual experience
- Indirect realism says we directly perceive mind-dependent sense-data caused by mind-independent objects
- Locke distinguishes between primary qualities in objects and secondary qualities as powers to produce sensations
- Indirect realism explains perceptual error well but faces the veil of perception and scepticism
- Locke appeals to the involuntary nature of experience and coherence of the senses, and Russell appeals to the best hypothesis
- Berkeley’s idealism denies mind-independent matter and claims ordinary objects are mind-dependent ideas
- Berkeley attacks Locke’s primary/secondary quality distinction and uses the likeness principle and Master Argument
- Berkeley’s idealism faces problems from illusion and hallucination, the risk of solipsism, and its appeal to God
- A strong AQA evaluation compares theories by asking which best explains perception without creating worse sceptical problems

## Key Terms and Concepts

- perception
- direct realism
- perceptual variation
- hallucination
- disjunctivism
- indirect realism
- sense-data
- primary qualities
- secondary qualities
- veil of perception
- Berkeley’s idealism
- esse est percipi
- likeness principle
- Master Argument
- solipsism


Epistemology - Perception