Epistemology - Knowledge from Perception

What is realism?

Realism is the position that claims that we perceive physical objects directly and that there are physical objects that exist outside the mind and do not depend upon perception.

What is direct realism?

Direct realism is the claim that we perceive objects directly and all the properties of the object belong to the object itself, independent of the mind. According to direct realism, our perceptions are unmediated and as such there are only two things involved in perception: The perceiver and the perceived object.

Outline the support of Direct realism:

• Direct realism is in tune with common sense: We see the leaves as green because the are green.

• It explains consistency in our perceptions. Our perception of objects is consistent and logical because the objects exist independently of our mind and follow the laws of nature

• It avoids scepticism, giving us a clear account of how it is that we come to have knowledge of the world: we know about it because our senser provide immediate access to its true nature

Outline the argument from illusion against direct realism:

• The argument from illusion states that direct realism cannot be a valid description of how we perceive things, as sometimes objects can appear differently under certain circumstances.

• It states that there are occasions where you can perceive an object as one thing, when in fact it is another; such as how an oar appears crooked when semi-submerged despite being straight when removed from the water.

• These experiences give us a representation of the object that is not veridical, and are indistinguishable from the true form of an object unless you are already familiar with the illusion.

• Since these deceptive experiences cannot, by definition, be a true representation of the object, the conclusion is drawn that what we immediately perceive is not the true nature of the world, since what we perceive does not match the properties of the object.

How could a direct realist respond to the argument from illusion: 

• A direct realist may argue that in these situations the senses do reveal reality to us, we just occasionally misinterpret it when we make hasty generalisations.

• Normally we can understand that an oar appears crooked in water because of how light refracts in different mediums and we are not fooled by it, unless we make a rash judgement and misinterpret the information attained by our eyes.

• Additionally, it can be argued that just because something is misinterpreted, it does not mean that we are instead perceiving a separate appearance distinct from reality. A direct realist could reason that it is possible to perceive a straight oar as crooked without implying we directly perceive the crooked oar and then indirectly perceive the straight oar.

• So a direct realist may argue that we should instead say the oar “appears crooked”, rather than there “is a crooked oar appearance”.

What is the argument from perceptual variation against direct realism?

• The argument from perceptual variation is an objection meant to undermine direct realism.

• It states that ones perception of an object changes according to the positions it is perceived in, for example a ball may appear blue in the light but black in the shade.

• Since we know that the object itself must not change we also know that its properties are constant, as any change in the properties would cause a change in the object itself.

• If the properties are constant and our perceptions of reality were unmediated, the ball would appear the same in every condition.

• Therefore, since the object appears different we can deduce that our perceptions of the object and the object itself must be separate.

 

Explain Russell’s table example against direct realism: 

• Russell uses the example of a table to show that how we attempt to perceive objects appears to change based on our perception.

• He claims that we have habits of judging the “real” shapes of things using our brain, however we do this so unreflectingly that we believe we actually are seeing the real shape.

• For example, when we see a table at an angle, our brain evaluates the perspective and comes to the conclusion that we are seeing a square table, however we merely believe that we are seeing a square table directly, without acknowledging that we have constructed the real shape in our mind 

• The way the table looks also constantly changes as the conditions change (e.g. A table will appear darker if the lights are turned off, so what we see and feel is merely the “apparent” shape and texture, which we believe to be reality

How may a direct realist defend against the argument from perceptual variation?

• A direct realist may argue that there is no problem with accepting that an object appears to change, and there is no need to include an extra factor such as sense data 

• British philosopher Galen Strawman argues that there is a “real” colour, shape, taste, etc. These properties change when the conditions change, however under “optimum” conditions, the properties of the object would be the same for everyone who perceives the object in the same way. 

Outline the argument from hallucination against direct realism:

• The argument from hallucinations is an objection meant to undermine direct realism by raising the issue of hallucination.

• Hallucinations are cases when we perceive something that is not actually there. For example, an inebriated person may perceive a pink elephant, however once they become sober it is apparent that the elephant was merely a hallucination.

• If direct realism were true, then the elephant would have to exist in reality, however it does not.

• Therefore, it appears that direct realism cannot be true.

How might a direct realist respond to the argument from hallucinations?

• A direct realist may argue that hallucinations are a rare occurrence that most people do not have. We should, therefore, not concern ourselves with these. (Not a good counterargument due to refutation by counterexample (A theory can be disproved with a single counterexample))

• It may also be argued that we know the difference between hallucinations and veridical perception as we can rationally know that, for example, there is no such thing as a pink elephant, despite the visual evidence that suggests otherwise. 

Outline the time lag argument against direct realism:

• The time lag argument is an objection against direct realism that leverages the fact that it takes time (even incredibly small amounts) for light to reach our eyes. 

• In the time it takes for us to perceive the object it may have changed or not exist at all, as we only perceive a delayed impression of the object and its properties. 

• For example, some stars are billions of light years away, so the light takes very long times to reach our eyes. By the time we are capable of seeing the stars they most likely no longer exist. 

• Therefore, since we perceive a delayed impression of an object, we cannot truly perceive it directly.

How might a direct realist respond to the time lag argument? 

• The direct realist can argue that this response confuses what we perceive with how we perceive it.

• Yes, we perceive objects via light and sound waves and, yes, it takes time for these light and sound waves to travel through space.

• But what we are perceiving is still a mind-independent object (it’s not sense data or some other mind-dependent thing) – it’s just we are perceiving the object as it was moments ago rather than how it is now.

What is indirect realism?

• Indirect realism is a realist theory of perception, meaning it believes that mind independent objects and their primary properties exist.

• It claims that we independently perceive mind dependent phenomena known as “sense data,” which Bertrand Russell defined as the “content” of our immediate sensory perception, and their properties rather than perceiving the objects directly.

What is sense data?

• Russell defined sense data as the “content” of our immediate sensory perception, and their properties rather than perceiving the objects directly.

• These non-physical sense data represent the physical mind independent objects and their properties.

• Indirect realism also states that our non-physical sense data are caused by the physical mind independent objects due to their effects on our physical bodies.

What reasons can be given to support indirect realism:

Indirect realism is capable of accounting for the flaws in Direct realism, such as issues from illusions, hallucinations and the time lag argument, since what we perceive does not need to be an accurate representation of reality.

Explain Locke’s primary/secondary quality distinction

• According to Locke, primary qualities are ones that belong to the object, such as mass and solidity.

• These are utterly inseparable from the object, meaning regardless of the conditions, unless the object itself is changed, the properties cannot change.

• Conversely, secondary qualities are ones that belong to the subject, such as colour or smell.

• These properties are dependent on the perceiver and are subjective, meaning they cannot be measured and can change depending on the conditions.

• For example, a ball may have the primary quality of being round and the perceived secondary quality of being blue. If I move the ball into a dark room the secondary quality of “blueness” changes to “blackness” as the conditions change.

Explain Locke’s support for his primary/secondary quality distinction:

• Locke argued that primary qualities were ‘utterly inseparable’ from an object, meaning that however an object is altered (such as by cutting it into smaller pieces), its parts must retain some shape, size and other primary qualities.

• Without primary qualities such as shape or size it does not appear that an object can be material at all

• Locke presents his argument in the following format: If you continually divide an object its parts must retain qualities such as size, even if they can no longer be perceived. Therefore primary qualities must exist mind independently

Explain how Locke’s primary/secondary quality distinction solves the issue of perceptual variation:

• Locke claims that perceptual variation is a result of the mutable nature of secondary qualities, which are dependent on the perceiver and so can be changed

• For example, if I dip my hands in a bowl of lukewarm water I will perceive it as lukewarm, however if I place my hands in an ice box before dipping them then the bowl will feel extremely hot. This perceptual variation can be explained as sensations such as “heat” or “cold” are secondary qualities, and so can change.

Explain the issue that indirect realism leads to scepticism about the existence of mind independent objects:

• According to indirect realism we are only directly aware of mind dependent sense data, which represents mind independent objects

• However, we know that our senses can deceive us. It is possible for us to hallucinate and see things that are not there

• It is therefore conceivable that our sense data does not correspond to any material reality at all, but is instead being manipulated. For example, it is possible that we could be a brain in a vat being electrically stimulated to make us think.

• These possibilities show that scepticism about a mind independent world is possible, as direct realism cannot directly refute them

• This is known as a “veil of perception”. Since we cannot directly observe reality we cannot prove that it exists

Explain Locke’s response regarding the involuntary nature of perception to the claim that indirect realism leads to scepticism about the existence of mind independent objects.

• Locke points out that we are not in control of our sense data

• He claims that if there was no mind independent world then we would be in control of our own perceptions, so the fact that we cannot choose what we perceive is evidence that the sources of our sensations must be external

Explain the argument from the coherence of experience against the claim that Indirect realism leads to scepticism about the existence of mind independent objects:

Locke:

• Locke claims that the external world must exist because our senses cohere

• For example, writing on a piece of paper will change how it looks, so my sight and the sense of my hand moving on the paper coheres.

• I cannot cause the words to appear on the paper by imagination, I must write them and once they are written they cannot be changed.

• Locke argued that this leaves “little room for doubt” that there is an external world

Cockburn:

• Cockburn argues that if we had just one sense then we wouldn’t know about a world beyond the inner world that we are directly aware of

• She acknowledges that one sense bears no resemblance to another. For example my perception of physically handling a coin is nothing like my perception of seeing the coin

• However, the fact that we do experience a connection between the ideas of an object gained through different senses suggests that objects really do exist. This is because we learn through experience.

• We cannot learn the connection because the senses resemble each other as they do not. Instead we learn the connection through experience that a specific type of change in sensation, such as a coin feeling dirty, corresponds with a change in another sense, the coin appearing dirty.

• The correspondence between these senses is always consistent, so there must be something other than the mind that produces this law-like regularity

• Cockburn then claims that it must be the existence of an external, objective, world

Explain Russell’s best hypothesis theory:

• Russell accepted that there was no deductive proof for a material reality, but you also cannot prove that there is no external world. Either the external world exists or it does not, and we are unable to conclusively prove either option.

• Russell asserts that it is the “best hypothesis” that the external world exists, which can be explained through the following example: Imagine walking into a room and seeing a cat sitting on a sofa. You then leave the room, but when you return the cat is on the floor. Either the external world does not exist and the cat dematerialised when I turned around and reappeared on the floor, or the external world does exist and the cat moved from the sofa to the floor while my back was turned.

• Russell asserts that the second option is the “natural view” urged by “every principle of simplicity”, and so the existence of the external world is the best hypothesis

Explain Berkeley’s argument that ideas cannot be like material objects:

• My idea of a tree (just a placeholder) has certain qualities

• However, these qualities depend on the mind

• To say that my idea of a tree resembles a real, material tree is impossible as ideas are fleeting and changing, while material objects are supposed to be permanent and unchanging

• Therefore, anything outside of the mind cannot possess the qualities of the things that I perceive

• So, my perceptions of objects cannot resemble the actual material object

What is idealism?

• Idealism is an anti realist theory which claims that all that exists are minds and their ideas

• There are no mind independent objects in idealism, and there is no reality outside of the mind

• All objects are just collections of ideas within the mind

What does Berkeley claim is the reason that objects remain consistent in idealism?

• Berkeley rejects the claim that objects only exist when being perceived by human minds, instead arguing that the universe is sustained in existence through being perceived by the infinite mind of God

• God directly causes our ideas or sense data

What is the argument for idealism relating to the problems with primary and secondary qualities?

• According to Locke, primary qualities are independent of a perceiver, whilst secondary qualities depend on a perceiver

• However, many primary qualities appear to change depending on the conditions in which they are perceived. For example, a coin looks round from above, but elliptical from an angle

• Secondly, Berkeley claims we are unable to perceive an object with no secondary qualities. For example, imagine a banana with no colour, shape, smell or taste. It is impossible to conceive of this, as a banana without colour would not be visible and so could not be perceived. This may mean that colour is a primary quality, creating a contradiction as it appears to be dependent on the conditions in which it is perceived.