Epistemology: Direct realism

Epistemology 2 - Perception as a source of knowledge - A 'Direct realism'

Direct realism is also known as the ... view

'common sense'

Direct realism

The theory that physical objects exist mind-independently and the immediate objects of perception are mind-independent objects and their properties

Objections to direct realism

The argument from illusion, the argument from hallucination, the time-lag argument, perceptual variation

The argument from illusion (as an objection to direct realism)

In an illusion, we perceive an object as having some property it doesn't actually have; what we perceive can't be the physical object and its properties. In these cases we either perceive sense data:

Bertrand Russell: the immediate objects of our perception are sense data (mind-dependent mental images or representations of physical objects)
- in illusions, we see sense data, and not physical objects, immediately

P1: We perceive something as having some property F (e.g. an oar that is crooked)
P2: When we perceive something as having some property F, then there is something that is F (something we see is F)
P3: In an illusion, the physical object does not have the property F (the oar is not crooked)
C1: Therefore, in illusions, what has the property F is something mental, a sense-datum
C2: Therefore, in illusions, we see sense data, and not pysical objects, immediately

- the critic of direct realism wants to show that we perceive sense data not just in cases of illusion, but in all cases of perception: illusions can be subjectively indistinguishable from veridical perception. Therefore, we see the same thing, namely sense data, in both illusions and veridical peception

Veridical perception

Acts of perception that accurately represent the object and its properties

Subjectively indistinguishable

Two perceptions are subjectively indistinguishable if you can't tell them apart just from the experience

Perceptual variation (as an objection to direct realism)

Bertrand Russell points out that an object (e.g. a shiny brown table) will look different depending on your angle and the time of day
- the properties we perceive change but the properties of the object (e.g. table) don't, so we can't be perceiving the actual properties of the table

P1: There are variations in perception
P2: Our perception varies without corresponding variation in the physical object we perceive
C1: Therefore, the properties objects have and the properties they appear to have are not the same
C2: Therefore, what we are immediately aware of in perception is not exactly the same as reality
C3: Therefore, we do not perceive physical objects directly

Relational property

A property that something/someone has in relation to something/someone else (e.g. 'being north of', 'looking beige')

Intrinsic property

A property that something/someone has in itself (e.g. 'being beige', 'being wooden')

The direct realist response to the argument from illusion and perceptual variation

Relational properties:
- what we directly perceive in these cases are not the properties of sense data but the relational properties of the objects
- e.g. in the crooked pencil illusion, we perceive the relational property 'looking crooked' (to an observer when it's in water)
- e.g. in the shiny table case, we perceive the relational proerty 'looking shiny' (from a certain angle to an observer)

The argument from hallucination (as an objection to direct realism)

In hallucinations, we perceive an object with properties but there is not object there at all, so what are we perceiving?

P1: Hallucinations occur when a person perceives something which doesn't exist outside their mind
C1: So what they perceive, the hallucination, exists only in their mind
P2: Hallucinations can be subjectively indistinguishable from veridical perception
P3: But if hallucinations and veridical perceptions are subjectively indistinguishable, then the person must be aware of the same thing in both cases
C2: What we are directly aware of during veridical perception must also be in the mind
C3: Therefore, we perceive the world indirectly and direct realism is false

Direct realist responses to the argument from hallucination

1. Hallucinations and veridical perception are not actually subjectively indistinguishable, otherwise we wouldn't detect hallucinations and know they exist
- counter-response: is it true that this is how we identify hallucinations? Is it not because they don't fit with our usual experience?

2. Direct realists can adopt disjunctivism (the view that hallucination and veridical perception involve different processes): either you perceive physical objects directly with no sense data (VP) or you perceive sense data (hallucinations)

The time-lag argument (as an objection to direct realism)

When you look at something, what you're seeing may not longer exist, meaning you cannot really be seeing it so must be seeing sense data

P1: The light from distant objects (such as the sun) takes time to reach our eyes
C1: So what we are seeing now may no longer exist
C2: Therefore, what we are seeing and what is there are different
P2: This is no less true for physical objects at any distance
C3: Therefore, what we directly see are appearances, not physical objects, and direct realism is false

Direct realist response to the time-lag argument

C1 doesn't imply C2. We directly perceive objects as they were, not as they are now, but we still perceive the object, not sense data.