Extraordinary experiences, the inexplicable, and encounters with the unknown have fascinated philosophers, artists, scientists, and people since prehistoric times, across all cultures, profoundly impacting humanity's worldview and spirituality. Since prehistory, shamans have explored the dimensions of the unknown, probing realms beyond the limits of ordinary consciousness and the visible, to understand humanity's relationship with nature and care for the suffering. But making the invisible visible and comprehensible is also the specific task of philosophy and science.
The Galilean sciences emerged from the rationalist revolution of the 17th century and a political compromise with the Church: the former led to investigating reality with a strictly mechanistic, quantitative, mathematical-geometric perspective, while the latter compelled a limitation of the investigative field to the physical world for political reasons (Facco & Tagliagambe, 2020). The dominant mechanistic reductionist paradigm in science, by its nature, cannot comprehend subjective phenomena, i.e., the psyche, consciousness, qualia, and the meaning of experience. It is therefore not surprising that the founding of the science of consciousness in the 1980s (over three centuries later than the emergence of the new sciences) sparked a debate of an essentially metaphysical nature. This debate has unfolded between the dominant materialist monist view of the "hard" sciences, which seeks to reduce consciousness to its neural correlates, and the view of those who believe it cannot be reduced to them. Thus, the method of study that allows for a correct understanding of the nature of consciousness and its place in the world is still not definitively clear or universally accepted (Facco, 2022a; Facco et al., 2023; Facco & Fracas, 2018).
In this regard, it is worth noting that in 1998 Christof Koch (a neuroscientist advocating for the reduction of consciousness to its neural correlates) bet with David Chalmers (a philosopher advocating for its irreducibility and currently co-director of the Center for Mind, Brain and Consciousness at New York University) that the neurophysiological mechanism of consciousness would be discovered within 25 years. On June 23, 2023, both scientists publicly agreed that the winner of the bet was David Chalmers, who received a case of fine Portuguese wine at the meeting of the Association for the Scientific Study of Consciousness (ASSC) held in New York.
Non-ordinary manifestations of consciousness, seemingly strange, both pathological and non-pathological, have been grouped under the label of altered states of consciousness, ASC (Ludwig, 1966; Vaitl et al., 2005);however, the concept of ASC and its current systematization are debatable. According to Ludwig, the term ASC indicates
"Any mental state... that represents a deviation in subjective experience or psychological functioning... from the waking consciousness" (Ludwig, 1966, p. 225).
In 2005, the ASC Consortium classified ASCs concerning their onset (Vaitl et al., 2005) as follows:
a) spontaneous (e.g., hypnagogic states);
b) induced by physical (e.g., extreme environmental conditions) or physiological means (e.g., breathing maneuvers, fasting, or orgasm);
c) induced by psychological means (e.g., sensory deprivation, rhythm of percussion and dance, relaxation, meditation, hypnosis);
d) induced by diseases (e.g., psychosis, coma, epilepsy).
According to the authors, the normal flow of consciousness depends on integrated neural processes, whose modifications likely lead to the onset of ASCs, but their nature remains largely unknown. The most relevant element is the recognition of the need to consider the first-person perspective for an appropriate understanding of ASCs, that is, the subject's narrative of the experience. Vaitl et al.'s (2005) classification is largely incomplete and includes a heterogeneous set of conditions, which seems to create more confusion than clarity (Tab. 1). The fundamental approach of the empirical-descriptive method adopted also seems fragile and debatable for several reasons, which will be briefly analyzed below.
Critique of the Concept of ASC
A classification of ASCs based on the stimuli that elicit them is debatable because there are no specific stimuli capable of producing individual ASCs, while different ASCs can have significant common aspects or even overlap in a similar framework.
Including pathological states in the chapter on ASCs creates more confusion than clarity, as it can implicitly confuse non-pathological experiences with dysfunctional phenomena, lumping them all together. Equally debatable is the mechanistic attempt to reduce certain ASCs, such as mystical experiences and Near-Death Experiences (NDEs), to mere dysfunctional brain mechanisms. The most glaring example is the mystical experiences of St. Paul and their hypothetical connection to temporal lobe epilepsy, an interpretation that neither accounts for nor can understand their profound significance and philosophical-existential implications; the same applies to great artistic inspirations, with van Gogh as a notable example due to the hypothetical connection with psychiatric disorders (Facco, 2010, pp. 143-152).
The main criticism of the term ASC is its implication of abnormality compared to ordinary consciousness. It is worth highlighting the ambiguity of the English term altered; although it corresponds to the Italian term modificato (which in itself does not indicate abnormality), it can also imply a disorder, a dysfunction, or a deficit compared to a state of normality.
Beyond linguistic ambiguities, the issue has profound epistemological implications, depending closely on what is meant by normality, alteration, and disease. If their definition within the realm of physical disorders is far from free of uncertainties (Facco, Casiglia, et al., 2017), the issue is even more uncertain regarding consciousness because there is no clear, univocal, and exhaustive definition of what consciousness is, let alone what should be meant by "normal" consciousness (Facco, Lucangeli, et al., 2017; Facco & Fracas, 2018).
Ordinary consciousness is also cultural and diachronic in nature, as Julian Jaynes rightly stated, meaning it is inseparable from history and cannot be understood outside of it (Jaynes, 2014); for example, various manifestations of consciousness that were considered normal, accepted, or even welcomed in antiquity—such as premonitory dreams, oracles, and visions of deities suggesting behaviors and solutions to problems—are a priori considered dysfunctional hallucinatory manifestations in the positivist-materialist worldview due to their incompatibility with the adopted axioms, theories, and world model.
Thus, the classification of ASCs is criticized both for defining everything that appears different from ordinary consciousness as altered—based on an implicit, undefined, and perhaps undefinable idea of normality—and because some ASCs like hypnosis and meditation are not altered states but rather valuable, intentional introspective activities of the mind that are entirely physiological and capable of empowering one's control over mind and body.
Curiously, sleep has been considered an ASC due to its difference from wakefulness. Although the two conditions are certainly different, sleep, in which we spend about a third of our lives, is inseparably linked to wakefulness as part of a single cycle that underpins life itself, essential for maintaining "normal" consciousness, physical and mental health, and adapting to reality. It would perhaps be more accurate to consider the wake-sleep cycle as an inseparable dynamic unit, within which we continuously oscillate between one and the other and between different levels of wakefulness within each phase, with a continuous flow of information and their processing products between consciousness and the unconscious. Thus, wakefulness and sleep are separable only for descriptive convenience but constitute an inseparable continuum, not distinct ontological entities. Defining sleep as an ASC seems as absurd as defining night as an altered state of day in astronomy.
Similarly, the unfortunate history of hypnosis has been characterized by significant therapeutic effects associated with a prejudiced rejection by the medical community, a problem with profound epistemological implications (Facco, 2022b, 2024). Other ASCs, such as mystical experiences, NDEs, and everything with the scent of transcendence—an intolerable odor for the monist materialist "hard" scientist—have been rejected a priori due to their incompatibility with materialist metaphysics.
Non-Ordinary Expressions of the Mind
From the brief discussion, it is evident that the dominant perspective in science is insufficient to address both subjective phenomena and ASCs. As William James wisely stated at the beginning of the last century,
"Our ordinary consciousness is but one special type of consciousness, while all about it, parted from it by the filmiest of screens, there lie potential forms of consciousness entirely different. We may go through life without suspecting their existence; but apply the requisite stimulus, and at a touch they are there in all their completeness, definite types of mentality that probably somewhere have their field of application and adaptation. No account of the universe in its totality can be final which leaves these other forms of consciousness quite disregarded" (James, 1917, Lectures XVI and XVII, Mysticism. In: The Varieties of Religious Experiences [James, 1958]).
The introduction of the concept of Anomalous Experiences (Anomalous Experiences, AE), defined a group of non-pathological experiences that are uncommon, inconsistent, and divergent from conventionally accepted experiences; however, meditation and hypnosis are not included in AEs because they may or may not give rise to unusual experiences depending on their conduct (Cardeña et al., 2014). Subsequently, the term Non-Ordinary Mental ExpressionsNon-Ordinary Mental Expressions, NOME) was introduced (Cardeña & Facco, 2015; Facco, 2014; Facco, Agrillo, & Greyson, 2015), to encompass a broader range of experiences, including non-pathological ASCs, AEs, and techniques capable of inducing NOMEs, such as hypnosis, meditation, and lucid dreaming.
The term "non-ordinary" avoids any prejudice or implicit idea of abnormality or apparent and suspicious strangeness, emphasizing instead the diversity of these conditions compared to what is conventionally admitted. The concept of NOME thus underscores the epistemological and metaphysical nature of the issues raised by their description and study, a problem also at the heart of the study of consciousness and the Self (Facco, Al Khafaji, et al., 2019; Facco & Fracas, 2018).
Table 2 below lists the NOMEs; they have been included in alphabetical order to avoid, at least for the moment, arbitrary categorizations. Thus, Table 2 constitutes only a preliminary and provisional framework subject to further modifications.
Among the NOMEs, higher states of consciousness have been duly included, a topic of great interest but neglected and not understood by the empiricist and materialist approach. This issue is crucial as it concerns understanding the nature of the Self and the pursuit of its highest realization, a problem with a long tradition spanning both East and West from the boundaries of prehistory to modern philosophy and psychology. The problem must be approached with a transdisciplinary and transcultural approach and a metaphilosophical perspective (Facco, 2014; Facco, Al Khafaji, et al., 2019).
In the list of NOMEs, some phenomena traditionally belonging to the parapsychological realm have been included for the sake of epistemological consistency. However, this choice necessitates a brief description of the reasons for their inclusion to avoid possible misunderstandings. In psychology, Galimberti (2006) distinguishes between phenomena of extrasensory perception (ESP) and those of psychokinesis (PK) and provides a precise definition. The former are perceptions that do not utilize the five known senses and include clairvoyance, retrocognition, precognition, and telepathy. PK, on the other hand, is the influence of a subject on a physical system in the absence of known energies and forces. ESP and PK have been classified according to the criteria proposed by Etzel Cardeña (2018).
The unsettling aspect of these phenomena arises from their apparent incompatibility with the accepted knowledge and theories about the functioning of the human mind. It is important to note, however, that the facts themselves can only be true or false, never parapsychological; their classification within the realm of parapsychology depends on their apparent implausibility, which is an expression of the spirit of the time, that is, the metaphysics adopted in any given historical period. The critical issue, therefore, is not the facts themselves, and it is the specific duty of science to study them correctly, understand them, and (following Popper's philosophy) falsify them. If some of these phenomena were to be proven, they should become part of the accepted reality, but such an event would simultaneously entail a modification of the known laws of nature. In summary, the division between science and parapsychology is nonsensical when parapsychology uses a rigorous scientific method, and science does not prejudicially reject what appears incompatible with the adopted axioms. For this reason, some phenomena of this type have been rightfully included in the list of NOMEs.
The empirical evidence supporting the reality of these phenomena has been brilliantly summarized in a recent review by Etzel Cardeña (2018). The author reports data from 11 meta-analyses of experimental studies on various phenomena, categorized into two classes—anomalous perceptions and mental perturbations (apparent intentional influences on physical or biological objects)—involving a total of more than 1600 subjects. The data available in the international literature suggest the following conclusions: a) it is possible to gather information unconventionally, that is, extrasensorially and without physical interaction with objects, especially under conditions of reduced mental and environmental noise, and when the information is reported freely, whether verbally or visually; b) at an unconscious level, our physiological system responds differently to pleasant or unpleasant, useful or dangerous information, even when such information is not gathered through sensory organs and is unpredictable; c) it is possible to mentally influence objects, both biological and physical, intentionally and at any distance; d) generally, these effects are not macroscopic and thus can only be detected using appropriate statistical techniques; e) the effects vary widely among individuals, with notable differences in the ability to control one's mental contents (for example, through the use of meditation techniques).
In conclusion, a proper classification of NOME must take the following facts into account:
1. Different stimuli can promote or give rise to similar or even identical NOME;
2. Some NOME, such as hallucinatory experiences and visions, can be considered either as NOME in themselves or as partial elements of more complex NOME;
3. A correct framework requires a deeper understanding of their nature and the underlying mental processes;
4. NOME, no matter how strange or bizarre they may appear, are not in themselves dysfunctional or pathological manifestations but rather a curious part of a still poorly understood physiology of the mind. Their corresponding pathological manifestations are the uncontrolled dysfunctional exacerbations of physiological phenomena;
5. A rigorously skeptical attitude is essential, in the original sense of the term—σκέψις (skèpsis: observation, inquiry, doubt)—meaning to neither accept nor reject anything a priori, but to consciously cultivate doubt and the necessary philosophical perplexity in the face of all that remains unknown or appears incomprehensible. In other words, it is necessary—as Aristotle himself recommends in the Metaphysics (1005b, 1-5)—to constantly question the veracity of the adopted axioms to avoid the risk of a dogmatic drift and thus the negation of science itself, which should not be confused with exclusive adherence to a given paradigm.
Table 1: Classification of Altered States of Consciousness (ASC) according to Vaitl et al. (2005, slightly modified).
Origin: : Spontaneous > ASC: drowsiness, daydreaming, hypnagogic states, sleep and dreaming, near-death experiences
Origin: Physical factors > ASC: extreme environmental conditions
Origin: Physiological factors > ASC: fasting, sexual activity and orgasm, breathing maneuvers
Origin: Psychological factors > ASC: sensory deprivation, rhythm-induced trance, relaxation, meditation, hypnosis, biofeedback
Origin: Pathological factors > ASC: psychosis, coma, vegetative state, epilepsy
Origin: Pharmacological factors > ASC: (Not evaluated)
Tab. 2: Non-Ordinary Mental Expressions
1) Hallucinatory experiences and visions
a) Spontaneous
b) Hypnagogic and hypnopompic hallucinations
c) Hallucinogenic experiences
2) Experiences of other identities
3) Mystical experiences
4) Unexplained healings
5) Hypnosis
6) Meditation
7) NDE
8) NDE-like
9) OBE
10) Extrasensory perceptions (anomalous or non-ordinary cognition)
a) Clairvoyance
b) Precognition, presentiment
c) Retrocognition
d) Telepathy
11) Psychokinesis:
a) Macropsychokinesis (anomalous force)
b) Micropsychokinesis (anomalous perturbation)
12) Alien abduction
13) Past life reminiscences
14) Synchronicity
15) Synesthesia
16) Lucid dreaming
17) Higher states of consciousness
a) Expansion of the Self (Russell, 1912)
b) Expansion of the Self beyond ordinary states (Arieti, 1967)
c) Epoptéia (Aristotle)
d) Enlightenment
e) Spiritual Self and N2O experience (James, 1958)
f) Superconscious (Assagioli, 1988)
18) Stigmata
19) Xenoglossy
20) Trance
