1. Introduction

The goal of the current paper is to investigate in detail a key question: Is there an imminent distinction between reality and dreams? The question of whether it is feasible to develop an ontology for lucid dreams that is on par with reality is an awkward one. Traditional common sense has long taken perception to serve as a window to the outside world, routinely relegating dreams to illusory or unreal products. Contemporary discourse within the worlds of phenomenology, psychological and existential thought, however, has uncovered an original thesis: that perception does not simply mean receptive reception, but instead serves to represent an active building of the world through the subject. If both perception and imagination represent constructive experiences, then the limit separating reality from dreams is in need of re-evaluation. Investigation of a “lucid dream ontology” thus presents challenges to traditional perceptual realism and encourages philosophical questions towards such notions as freedom, authenticity, and the meaning of existence.

2. A survey of classical positions

With regard to classical philosophical and psychological thought, dreams have often been regarded as fundamentally distinct from reality. Reality is understood from outside in terms of the objective appearance of the external environment, and involvement would result from “perception”, and from the inside in terms of the subjective products of the mind, and involvement would result from “imagination”. But with more visions coming, the assumption is challenged: whether perception and imagination are necessarily dichotomous is a matter of intense interest, and whether it is feasible to establish, on the basis of dreams, a novel ontology.

2.1. Classical understanding of dreaming

Freud, in the preface to The Interpretation of Dreams, noted that the dream is an opening to the unconscious, revealing in the psychological tradition the bent forms of repressed desire [1]. And so, in accordance with this, the dreams would be characterized as psychological internal activities, and not copies of the external reality. Here, again, this understanding directly fits the dividing line between reality and dreams: the latter is the mind’s only symbolic processing, and it has no external authenticity.

Philosophical tradition had it that Descartes posited the “dream argument” in Meditations on First Philosophy, thus ushering in the discussion of the possibility of separating in experience the question of whether human beings could differentiate between dream and waking life [2]. Here, Descartes champions the argument that dream worlds could hardly, if at all, be differentiated from reality, thus making it not feasible to demarcate starkly through just experience alone. It was not in denial that Descartes stood in distinguishing reality from dream life, but he argued that waking life had higher overall coherence and authenticity levels. Above-outlined framework upholds the epistemological differentiation for the “illusory” nature of dreams from that of the “real” nature of reality.

Ideally, major schools of thought in the fields of traditional psychology and philosophy have theorized that dreams conflict with reality. Dreams have been described as internal, subjective, and volatile, while reality is described as external, objective, and stable. This thought process has been major in analyzing and understanding reality and dreams, but it has had major unresolved questions in it. At the level of experience, the dichotomy between reality and dreams is not straightforward, since most individuals do not differentiate between them when they dream. The aspect of lucid dreaming, in which the dreamer is aware that it is in the dreaming state and has the capacity to have control, even complicates such dichotomization further.

2.2. Against traditional opinion

Hilary Putnam’s “brain-in-a-vat argument” is that if realism is correct, human consciousness might be that of a brain in nutrient fluid, and all experiences are just virtual impulses entered from a computer. Under such conditions, human beings could be completely false and yet never realize that [3]. That indicates that it is possible that the reality-dream border is just an illusion.

Furthermore, in Putnam’s “conceptual relativity argument”, questions of “what the world contains” are considered meaningless, for the existence of things depends on the adopted cognitive system [4, 5]. It is possible that one cognitive system would permit the understanding of an object as existing in the world, and another would regard the same object as a “collection” or an “event”. For instance, that piece of wood may be understood as an aggregation of wooden pieces or “the thing you sit on”. This indicates that reality is not a “seat of purely objective entity” outside of cognition and language, but it is highly entangled with human cognitive systems.

If Putnam’s thesis is taken, the differentiation of reality and dream would lose its ultimate basis. Since “reality” itself is built up from conceptual structures, the phenomena produced in the dream state may also, in turn, be treated as “real” in certain structures.

2.3. Lucid dreams

In lucid dreams, the dreamer is in a state of heightened awareness and is able to manipulate the dreamscape to varying degrees. This state violates the essential dichotomy of the distinction between dreams and reality. Lucid dream experiences owe the same coherence as experiences in full wakefulness. Furthermore, the fact that the dreamer is aware of the self in the dream separates the dreamscape from being totally severed from rational reality. As such, lucid dreaming peels back a border region, in which the dichotomies of perception and imagination, reality and dreams, stand not at all, but fluidly and openly connectable to each other. Against these thoughts, it emerges with a new perspective: perception and imagination remain ontologically unrelated. With respect to experiences in lucid dreams, imagination is speculated to form a “world construction”, and perception in the waking world is able to be taken in that respect. If this approach is accurate, it implies that dreams or dream beings form part of reality, carrying an ontological status that is coequal with that of the waking world (i.e., the perceptible world).

3. The ontology of perceptual realism

To discuss openly the ontological possibility of reality versus lucid dreams, one must revisit perceptual realism’s argumentative structure. Perceptual realism’s primary position is that the world is made up of perceivable things that exist independently of the subject’s consciousness. Thus, reality is considered to be a fixed outward existence, and dream states, in turn, are construed to be appendages or remnants of the external world. Logically, from this thought, one proceeds in the following steps:

Perceptual realism asserts the following proposition: (T1) reality consists of perceptible things. The perennial thesis of reality, proposed by the above theorist, relies for its validity on the idea of “perceptible”. Perception of the idea of reality, in relation to physical objects, phenomena, and events, relies for its validity on the impression it leaves on the senses. Per this stance, findings agree with empiricism, for the very basis for the reality existing is relies on its experiential nature [2]. Dreams, in the absence of actual, externally perceptible, thus tend to remain outside of the sphere of “reality”.

Secondly, perceptual realism advances the proposition that (T2) observable things are independent of the percipient. Object independence, that an object continues to exist and is qualified in spite of observation, is the root article of faith in realism. This idea is reflected in the continued existence of the moon, which is continued even when it is not directly perceived, and the falling tree’s creation of sound, which continues when unheard. Freud, admitting greatly to the psychological foundations of dreams, yet accepted their creation from leftover stuff of daily life, dependent on exterior objects [1]. Dreams, therefore, ontologically, are posterior to reality.

Thirdly, perceptual realism would enjoy its premise that perception is a result of entity and subject interactions. Perception is not internal in nature, but it is the outcome when external entities interact with the senses. Current ecological psychology accepts the fact that perception is determined by the “availability” of stimuli in the environment. Why is it that peculiar is that their real-time interaction is absent, and they survive based on internal mechanisms that make them spontaneously emerge, yet that is the reason why they are considered “unreal”.

With these foregoing hypotheses, T1–T3, perceptual realism advances the thesis of (T4) that mental events owe their genesis to perception only. Images, sounds, and stories contained in dreams are reconfigurations of wake observation. This thesis is in tune with Freud’s “residuary experience” hypothesis and conforms to the empiricist school, which maintains that the mind contains no content a priori.

Thus, the dream phenomenon termed (T5) relies on external reality for its reality. Perception of the subject for the generation of representations relies on the existence of observable objects in the world. The practice of manipulable lucid dreaming relies on existing experience. This approach is in contrast to the “brain in a vat” theory put forward by Putnam, that the existence of deception and illusion serves to mark the external reality as indispensable [3].

In short, (T6) dreams may be said ontologically to follow secondly. They arise as effects of reality, not as correlates of it. From Descartes to modern theorists, the majority is in agreement that even if dreams may raise epistemological doubt, they could not pose reality’s ontological status in question. Even though lucid dreaming proves to blur edges, it does not make the second-order nature of dreams ontologically changed.

4. The problem of perceptual realism and a case for the perception-dreaming identity

4.1. Three readings of T3 and their issues

The logical chain of perceptual realism (T1–T6) appears rigorous, yet conceals a crucial ambiguity at T3: How should the relationship between perception and objects be understood? This determines whether the distinction between perception and dreaming is necessarily required. T3 admits at least three interpretations: (T3.1) presentationism, (T3.2) representationalism, and (T3.3) constructivism—none of which is unavoidable.

Under the presentationist understanding (T3.1), perception is the “effect” or “imprint” of perceptible objects on the perceiver—that is, how objects present themselves in the subject’s consciousness. This stance continues the empiricist tradition: objects exist independently (T2) and directly influence the subject through sensory channels. Its strength lies in its intuitiveness, explaining why most people think, “I see the table because it is right in front of me.” However, the problem with this stance lies in its assumption of the stable independence of objects—that “perceptible entities exist independently of the perceiver”—an independence long challenged in both physics and phenomenology. The "observation collapse" hypothesis in quantum mechanics suggests that microscopic particles exist in a quantum superposition state when unobserved, collapsing into a concrete “state of existence” only upon observation [6]. This implies that the existence of objects in reality is not necessarily independent of observation but is influenced by the act of observation itself. If reality itself depends on perception or observation at certain levels, the boundary between dreams and reality becomes difficult to maintain: objects in dreams also manifest in the instant they are “observed (created),” and they are not ontologically distinct from “objective existence” in reality.

Representationalism holds that (T3.2) perception does not involve objects acting directly upon the subject, but rather the subject representing objects within the mind. This position aligns more closely with contemporary cognitive science's prevailing view that the brain constructs representations of the external world through information-processing mechanisms. This stance can explain phenomena like hallucinations and illusions: even without real objects, the subject can still generate representations and produce “perceptual” experiences [7]. However, representationalism still presupposes the existence of a prototypical object as a reference point, with mental activity aimed at reconstructing or simulating external objects. This implies that it fundamentally perpetuates the assumption of object independence, albeit more indirectly than presentationism.

Constructivism, in contrast, holds that (T3.3) perception is neither a passive reception of objects nor merely a representation of external objects. Rather, it is the active construction of perceptible “objects” by the subject through the interaction between mind and world. Under this framework, the external world is acknowledged to exist, but these “objects” are not entities independent of the mind; they are generated within the relationship between the subject and the world. In other words, “objects” are not mere things but “meaningful entities” inherently dependent on the subject’s constructive activity. This understanding draws heavily from phenomenology and post-realism [8, 9]. Contemporary scholars further note that dream experiences share many mechanisms of subjective consciousness and bodily perception with waking perception, suggesting an essential continuity between dreaming and waking perception. This supports the view that perception and dreaming share the same constructive nature [10]. From this perspective, the premises of T1 and T2 no longer hold: although an external world exists, perceptible objects are not entities independent of the mind but rather the joint product of mind and world. Consequently, perception and imagination converge in essence—perception is itself a form of imagination.

4.2. Perception is imagination: from experiential homogeneity to taxonomical reform

T1 The assumption that reality must consist of perceptible entities is precisely refuted by Putnam’s “argument from conceptual relativity”: reality is not unconditionally and directly given by the world itself, but depends on the conceptual frameworks people use to perceive the world [4]. Returning to the table example: when people assert that a “table” exists, this existence is not independent of humanity’s unconscious classification systems. Under different taxonomic frameworks, the same object can generate distinct conceptual entities. For instance, people may perceive a combination of atoms as a “table” rather than as “wood” or a “collection of molecules.” This demonstrates that the proposition “reality consists of perceptible entities” is not directly objectively present but depends on the construction of conceptual frameworks. This perspective suggests that if it is acknowledged that imagination is the subject’s constructive activity toward mental entities, then perception also falls within this category. Whether “seeing a table” or “dreaming of a table,” the subject grasps the mental entity of “table,” not some independently existing table itself.

The inferences of T5 and T6 persist in treating dreams as subordinate, yet this too warrants scrutiny. If it is acknowledged that perception itself is not merely passive reception but a constructive activity between the subject and the world [8], then the difference between dreams and perception is not one of category but of degree. Everyday perception is not a photographic reproduction of a pre-existing world, but a continuous construction of the world through the subject’s senses, attention, and meaning-making. For example, when entering an unfamiliar room, one does not simultaneously perceive every detail. Instead, selective attention and meaning-oriented processing construct an overall impression of the “room.” Unnoticed details remain in a state akin to “non-collapsed” particles: they exist potentially but remain outside conscious awareness. Dreams operate similarly. The dreamer generates and constructs a complete scene through selection, attention, and symbolism. The distinction between perception and imagination lies not in “reality” versus “illusion,” but in varying degrees of constructed manifestation.

Psychological research further indicates that dream imagery and waking visual perception exhibit significant similarities in brain activity patterns, both involving activation of the visual cortex and multisensory integration processes [11]. This suggests that the neural foundations of perception and dreaming share homogeneous differences rather than fundamental distinctions.

Within this framework, traditional classification systems require reconstruction. If it is acknowledged that perception is imagination, then no ontological difference exists between reality and dreams—only a difference in the degree of world construction: reality may simply be a socialized and stabilized form of a certain dream state, while dreams represent the freer aspect of this construction. Ontologically, both hold equal status as constructive products generated within the relationship between the subject and the world.

5. The ontology built on lucid dreams: from the viewpoint of existentialism

5.1. Why perception rather than dreaming is granted the status of “reality”, if both are constructs

If the position proposed earlier is accepted—that perception is essentially a form of imagination—then the waking state and dreams are no longer ontologically diametrically opposed. If both perception and dreams are equally the subject’s construction of the world, it must be asked: why is one construction (perception) granted the status of “reality” by society and philosophy, while the other (dreams) is deemed illusory? Traditionally, dreams have been dismissed as absurd and meaningless due to their lack of clear, traceable causal chains, while waking life is deemed real and meaningful because it operates under laws of causality, rules, and the possibility of external (human) verification. Contemporary lucid dream research, however, subverts this contrast.

Research by Windt and Noreika indicates that lucid dreaming experiences are often accompanied by heightened levels of self-awareness and a sense of meaning. This phenomenon is not merely a subjective perception but has been validated through neural mechanisms [11]. Furthermore, experiments by Voss et al. demonstrate that lucid dreamers can communicate with researchers via eye-tracking signals, proving they maintain a high state of consciousness within dreams [12]. In studies by Mota-Rolim and Araujo, numerous lucid dreamers reported experiencing greater “reality” in dreams than in waking life: sensory details felt richer, and freedom of action seemed more pronounced [13]. Research by Mason and Wakerley proposes that daydreaming and lucid dreaming form a continuum of conscious experience, exhibiting significant similarities in subjective perception and self-awareness. Their findings indicate that dream experiences are not entirely detached from waking life but rather represent an extension and construction of conscious experience [14]. This evidence suggests lucid dreams possess not only psychological authenticity but also neuroscientific reality comparable to waking perception. It implies that so-called “absurdity” and “meaning” are not determined by causal chains but by the subject’s sense of existence, freedom, and value.

Existentialism offers an interpretation. To explain these experiments from an existentialist perspective, consider a subject A whose life is filled with situations that are not merely meaningless but utterly absurd. A cannot find ultimate justification for existence in reality but is passively entangled in a chain without origin or purpose, often devoid of meaning. As Camus noted in The Myth of Sisyphus, the world is fundamentally absurd because it offers no ultimate response to humanity’s quest for meaning [15]. Yet subject A’s dreams, especially lucid dreams, can manifest intense authenticity and meaning: within them, the dreamer directly experiences the emergence of freedom and value. Subject A in a lucid dream can actively create, modify, and assign meaning, exhibiting an intense realness and authenticity. In this state, the dreamer not only feels free but also discovers value and purpose within the dreamscape—elements that remain fragmented in so-called “reality.” Thus, dream and reality undergo a reversal in terms of “authenticity”: the dream is real, while reality is illusory. In other words, “reality” is absurd, while dreams are more real.

Consequently, the binary distinction between dreams and reality lacks inherent necessity rooted in the essence of phenomena. Instead, it arises from cultural conventions, social consensus, and survival strategies. People believe waking perception is more real, not because it is ontologically superior, but because this belief serves greater functionality in social coordination and practical activities. From an existentialist perspective, this view holds not only because perception and dreams share structural homogeneity, but also because within the subject’s existential experience, the authenticity and sense of meaning conveyed by dreams can surpass reality. This renders the stance that “perception is imagination” not only theoretically coherent but also supported by lived experience.

5.2. How sartre and camus’ views support this ontology

In Being and Nothingness, Sartre posits that humans are “compelled to freedom,” an inescapable condition of existence [16]. In waking life, this freedom often manifests as a heavy burden: individuals must choose among countless possibilities without any absolute foundation. This predicament engenders anxiety and a sense of nothingness. However, in lucid dreaming, freedom manifests differently: individuals not only freely choose actions but also freely “create worlds.” Within the lucid dream realm, the subject’s freedom unfolds completely—a freedom characterized not by anxiety but by creativity and autonomy. Thus, lucid dreaming becomes the ultimate embodiment of Sartrean freedom.

Camus, meanwhile, emphasizes the inevitability of absurdity. For him, absurdity stems from the tension between humanity’s quest for meaning and the world's silence [15]. In waking life, people often confront this absurdity: the world appears indifferent, and the chain of meaning may snap at any moment. Yet in lucid dreams, the subject can not only construct meaning within the dreamscape but also experience a profound sense of authenticity in the process. In other words, dreams offer individuals an “anti-absurdity” experience. They do not dissolve absurdity but enable individuals to create meaning within it, thereby transcending the sense of meaninglessness in reality. This mutually corroborates the attitude of “surviving within absurdity” advocated by Camus.

Thus, a new ontological conclusion emerges: dreams are not appendages of reality but integral components of its constitution. Within Sartre’s framework, dreams represent the ultimate manifestation of freedom; within Camus’s framework, they constitute the subject’s means of creating meaning and resisting absurdity. Together, they demonstrate that “reality” encompasses not merely the waking world but all experiential existence, including dreams.

6. Conclusion

Through analyzing the relationship between perception and dreams, this paper argues a crucial position: perception and dreams are not sharply divided but belong to the same category of the subject’s constructive activity toward the world. Particularly in the experience of lucid dreaming, individuals can discover freedom, authenticity, and meaning, forming a stark contrast to the absurdity and fragmentation of everyday reality. Thus, the “reality” of wakefulness is not an absolute benchmark of truth, but rather a form endowed with “authenticity” within the realm of constructive experience. The proposal of lucid dream ontology not only reveals the multidimensional possibilities of human existence but also undermines the reality-dream dichotomy upon which realism relies. It invites people to reconsider the foundations of existence: authenticity may not reside in any predetermined world, but rather in the subject's manner of imbuing meaning upon the world through experience.