Disjunctivism and Naive Realism

Naive realism holds that veridical perception is a relation in which mind-independent objects and their properties partly constitute experience. Disjunctivism denies that a veridical perception and an indistinguishable hallucination must share one fundamental mental kind. The ordinary description "it visually seems that there is a red apple" covers a disjunction: either the subject sees the apple or merely seems to.

The view restores the world to perceptual experience rather than treating it only as a cause of an inner common factor. Its hardest task is giving a positive account of hallucination and preserving psychological explanation across good and bad cases.

The relational view

On naive realism, a veridical experience includes:

$$Subject\stackrel{perceptualrelation}{\leftrightarrow }Objectandproperties.$$

The object's presence is not an external condition added to an otherwise complete internal experience. It partly determines what experience the subject has. A perception of this red apple could not occur without this apple, even if an internally matching hallucination could occur.

"Naive" marks continuity with ordinary thought, not intellectual simplicity. Experience seems open to the world: the apple, not a representation or sense-datum, is what one attends to. The theory takes that appearance at face value.

The disjunctive claim

The argument from hallucination assumes:

1. perception and hallucination can be subjectively indistinguishable;
2. indistinguishable states share the same fundamental mental nature;
3. hallucination lacks a constitutive relation to an ordinary object;
4. therefore perception lacks that relation too.

Disjunctivism rejects premise 2. Indiscriminability is not identity. A perfect counterfeit may be indistinguishable from a banknote without sharing its origin or status. Likewise, hallucination can be indiscriminable from seeing without possessing the world-involving nature of seeing.

This blocks the common-factor inference while allowing shared neural causes, report dispositions, and phenomenal judgments. What it denies is that those shared properties exhaust the experience in the good case.

Positive and negative disjunctivism

A positive account characterises hallucination through its own representational, neural, or imaginative nature. The two disjuncts are distinct positive kinds that happen to be indiscriminable.

A negative account characterises a hallucination as an event that is indiscriminable from a veridical perception without specifying a common positive experiential essence. This is useful when hallucinations form a heterogeneous class with many causes.

Negative disjunctivism faces the charge of incompleteness. What is occurring in the subject? "Not knowably different from seeing" gives an epistemic relation to another case, not an account of the episode's intrinsic nature. Defenders answer that the demand for one positive hallucination kind is inherited from the rejected common-factor theory.

Causally matching hallucination

Imagine stimulating a brain so that its internal physical state exactly matches a veridical perceiver's state. If mental properties supervene locally on brain properties, the experiences must match. Naive realism denies local supervenience: the relation to the object contributes to the mental state.

The two cases may share every intrinsic neural property while differ relationally. This is no formal contradiction; content externalism already allows intrinsic duplicates to differ mentally because of environment.

The pressure is explanatory. If internal duplicates make identical reports, judgments, and actions, what work does the relational difference perform? The naive realist answers that it constitutes successful perception and factive knowledge even when it does not alter the local causal profile.

Phenomenal character

Strong naive realism says the phenomenal character of veridical perception is partly constituted by perceived properties. The redness of the apple helps constitute what the experience is like. A matching hallucination cannot literally share that character if the apple is absent.

How, then, can the cases be indistinguishable? The subject's inability to discriminate does not require shared character. Discrimination is a cognitive achievement with limits. A hallucination may be indiscriminable because it produces no available reason to judge that it is not seeing.

Critics argue that this makes phenomenal similarity mysterious. If both seem exactly red and apple-shaped, some common positive quality appears present. Disjunctivists may allow shared determinable character or representational appearance while denying that it is the most fundamental nature of the veridical state.

Illusion

Illusion is harder for naive realism than veridical perception. If a white wall looks yellow, the subject is related to the white wall, but the presented colour is inaccurate. The external object does not instantiate the apparent property.

Responses include:

• relational appearance: the wall has a relational property of looking yellow under these conditions;
• representational supplementation: perception is relational but also represents the object inaccurately;
• pluralism: illusions that preserve object contact belong to the good relational disjunct despite local misrepresentation.

The second creates a hybrid naive realism rather than a pure relation-only theory. It may be the most plausible response because direct object contact and representational error address different features.

Epistemological disjunctivism

When a subject sees that $p$, the fact that $p$ can be their reason for believing $p$. In a matching hallucination no such factive reason exists. Epistemological disjunctivism therefore denies that good and bad cases provide the same evidence.

This offers a response to scepticism. The possibility of hallucination does not reduce ordinary perceptual knowledge to an inference from neutral appearances. In good cases, subjects possess reasons that entail the truth.

The objection is reflective accessibility. If the subject cannot tell good from bad, how can their justification differ? Externalists about justification accept that one's epistemic position can depend on facts beyond reflective access. Internalists may retain equal justification while distinguishing knowledge through reliability.

Metaphysical disjunctivism does not entail the epistemological version. One can hold that experiences differ fundamentally while their subjectively accessible evidence is the same.

Explanatory generalisation

Psychology groups veridical perception and hallucination because both can lead to the same reports and actions. If they share no mental state, laws connecting experience to behaviour appear disjunctive.

Disjunctivists can preserve common properties at non-fundamental levels: both episodes may involve matching neural states, appearances, or indiscriminability relations. What they deny is that the shared property explains what veridical seeing fundamentally is.

This response limits the view. A common-factor psychology may explain downstream behaviour, while relational metaphysics explains perceptual success and phenomenal openness. Theories can divide labour rather than require one taxonomy at every level.

Direct realism without naivety

Naive realism does not imply that objects possess every property exactly as they appear, that perception is infallible, or that no neural processing occurs. It can accept perspectival variation, constancy mechanisms, attention, and learned skill. The claim is that in veridical experience these processes establish a relation to ordinary objects rather than terminate in an inner surrogate.

Nor does the view require all perception to be conscious. An organism may stand in information-bearing relations and guide action without phenomenal awareness. The constitutive claim concerns conscious veridical perception.

Comparison with intentionalism

Hybrid views are possible. A veridical experience may be relationally constituted while also representing the object, and hallucination may share representational but not relational features. The substantive issue is whether representation exhausts the good case.

Assessment

Disjunctivism blocks sceptical and metaphysical arguments that begin from a neutral inner appearance. It honours the apparent openness of perception and the epistemic difference between seeing and merely seeming. Its cost is asymmetry: the elegant account of the good case is paired with a less unified account of hallucination.

Whether that is a defect depends on the world. A heterogeneous category need not possess one essence merely because ordinary language groups its members. But a theory that rejects common kind must still explain the robust causal and phenomenal similarities that made the grouping attractive.

Selected references

• Brewer, Bill. Perception and Its Objects (2011).
• Haddock, Adrian and Fiona Macpherson, eds. Disjunctivism (2008).
• McDowell, John. "Criteria, Defeasibility, and Knowledge" (1982).
• Martin, M. G. F. "The Limits of Self-Awareness" (2004).
• Snowdon, Paul. "The Objects of Perceptual Experience" (1992).