The Pauli–Jung Conjecture and Its Relatives: A Formally Augmented Outline

3.1 Neither causal nor random

In quantum physics, measuring an entangled non-product state yields separate states that are non-locally correlated in a precise way, depending on the entangled state from which they derive. An entangled singlet pair state, for instance the state Φ pair of a particle pair, is not the same as the product of the states Φ 1 and Φ 2 of two separate particles. The decomposed states of the two separate particles arise from the pair state as soon as a property of the system, like spin, is measured. Together with a spin measurement at particle 1, the opposite spin becomes realized at particle 2, so that there are strict anticorrelations between the measured spins of the two separate particle states.

An ingenious inequality set up by Bell in 1964 expresses the classical assumption of a local reality where the entangled pair state would in fact be the same as the product state of the two separate particles. In a somewhat modified formulation, this inequality reads as follows:^[20]

where a and a ′ are measurement settings for particle 1, b and b ′ are measurement settings for particle 2, and E (.,.) expresses the expectation value of the measured spin pairs (+1, +1), ( +1, − 1 ), ( − 1 , +1), and ( − 1 , − 1 ) at particles 1 and 2 (+1/ − 1 stand for spin up/down). Calculating the values of E for measurements with different settings yields that their sum violates the limit posed by classical correlations, the value 2, exactly in the way quantum mechanics predicts, namely up to the value 2 2 .^[21] Many corresponding experiments so far have provided overwhelming evidence that local realism is violated by entangled quantum systems.^[22]

There is a stunning analogy of this line of argument with the Pauli–Jung conjecture sketched in Section 2, which matches exactly what is sometimes referred to as a “pullback metaphor”:^[23] structural relations in a new domain to be explored are pulled back to structural relations in a familiar domain. Just replace Φ pair with psychophysically neutral states Φ P P N , and Φ 1 and Φ 2 with mental states Φ M and physical states Φ P , and the basic scheme is the same. Neither in quantum entanglement nor in dual-aspect monism are the correlations due to causal interactions, and yet in neither of the two they are random. So it seems that quantum entanglement teaches us a lesson we might be able to apply to the bigger picture of mind–matter correlations as well.

However, there is a crucial difference between quantum correlations and mind–matter correlations, which calls for emphasis because of its significant consequences. While acausal quantum correlations between two particles Φ 1 and Φ 2 are purely statistical and perfectly reproducible across experiments, correlations ( Φ M ∼ Φ P ) between the mental and the physical are not. Since these correlations transgress the boundary of the physical toward the mental, they inevitably necessitate a subjective element that challenges reproducibility. Subjective experience is clearly something that physics, or any other science describing and explaining “objective” (physical) facts, cannot cover within its limits. To address this, Jung and Pauli offered the radical and brilliant idea that the currency of these correlations is not (quantitative) statistics, as in quantum physics, but (qualitative) meaning.^[24]

They expressed this idea with their proposal of synchronistic events consisting of acausally connected states Φ M and Φ P , whose correlations ( Φ M ∼ Φ P ) are not (or sufficiently unlikely) random. In addition, they are not only notable and striking but also exhibited as meaningful coincidences.^[25] The meaning that substantiates the correlations is attributed by the experiencing subject in its state Φ M . As an intrinsically relational concept, meaning correlates subjective states Φ M of mental representations with states Φ P of what they represent in the physical domain. In a way, the experience of meaning can thus be understood as a (“sixth”) sense modality for “perceiving” psychophysical correlations.^[26]

However, the subjective and generally irreproducible attribution of meaning does not entail that it is arbitrary: it is an (often symbolic) expression of the non-subjective, psychophysically neutral, archetypal state Φ P P N A from which it originates. If an archetypal pattern is activated, the correlation between a subject’s mental state Φ M A and its correlated physical state Φ P A is restricted to a range of experiences prescribed by the theme of the activated archetypal state Φ P P N A .^[27]

As a two-place relation between a mental representation and what it represents, the concept of meaning has been widely discussed as intentionality, or intentional content, in the philosophy of mind.^[28] Two differences to this standard discussion should be stressed. First, mental representations in the Pauli–Jung conjecture do not relate to what they represent in the outside physical world, but that “world” is itself regarded as an aspect of an underlying reality.^[29]

The second point is that the unfolded meaningful correlations ( Φ M ∼ Φ P ) derive from their origin in the psychophysically neutral domain, i.e., from archetypal pattern states Φ P P N A . This suggests that the experienced meaning is somehow implicitly preformed in those patterns irrespective of its manifestation through Φ M and Φ P and their correlation ( Φ M ∼ Φ P ) . Since at the psychophysically neutral archetypal level there is no subject–object distinction, it is a challenging question of whether and, if yes, how this implicit, dispositional core of meaning can itself be open to experience.^[30]

3.2 Structural and induced correlations

For a more systematic account of the correlations between the mental and physical aspects of an underlying psychophysically neutral reality, Atmanspacher and Fach suggested distinguishing structural and induced correlations.^[31] These two types of correlations in the framework of the Pauli–Jung conjecture will now be explained in more detail.

Structural correlations are considered as the consequence of a unidirectional manifestation of Φ P P N in both the mental and the physical, without the backreaction indicated in Section 2. Typical examples are psychosomatic correlations such as those between mental stress and physical blood pressure or the widely discussed neural correlates of conscious mental states. The “symmetric” intertwining relations π and μ discussed at the end of Section 2 belong to this class of structural correlations, which are pretty much established (even though they are usually not one-to-one), and they are stable and reproducible. Typically, they are never explicitly experienced as particularly meaningful, let alone numinous (as Jung occasionally demanded for synchronistic events). In this sense, they define a persistent correlation baseline that does not call for particular attention by the subject.

Nevertheless, they are manifestations of archetypal patterns. Since the correlations are robust, it makes sense to assume that the archetype from which they originate is always and ubiquitously constellated across time and irrespective of individual or societal differences. This is the case for those archetypes Jung identified as most fundamental, such as the principles of unity and duality, integration and differentiation. Splitting one (unity) into two (duality) is a basic principle in all Western epistemology (though less so in Eastern philosophies, hence culture may indeed make a difference), and it seems plausible to see such basic archetypes as responsible for structural, stable, and reproducible baseline correlations. Such correlations ( Φ M ∼ Φ P ) can be heuristically characterized by their vanishing difference from the baseline, Δ ( M ∼ P ) = 0 , omitting the index A for archetype because of its virtually context-independent significance in this case.^[32]

Induced correlations are correlations ( Φ M ∼ Φ P ) with a non-vanishing distance from the baseline and come in two variants: coincidence phenomena and dissociation phenomena. In coincidence phenomena, there are excess correlations between Φ M and Φ P above the baseline of structural (ordinary) correlations, while dissociation phenomena express deficit correlations between Φ M and Φ P below the baseline (see more details in Section 3.3). Both types of induced correlations can be heuristically characterized by | Δ ( M ∼ P ) | > 0 . Reason #1 for induced correlations is that they arise from archetypal patterns less fundamental than structural correlations. They are activated only under special circumstances rather than pervading entire cultural contexts. Reason #2 is the backreaction that makes it possible to induce changes of Φ P P N A from both Φ M A and Φ P A . These changes can in turn manifest themselves in M and P, creating further correlative experiences ( Φ M ∼ Φ P ) .

As an example, consider some subject in the imagined situation of grave personal loss in their immediate (emotional) environment. In Jungian terms, this situation may activate an archetypal pattern of grief. The corresponding state Φ P P N grief will manifest itself in states Φ M grief and Φ P grief and correlations ( Φ M grief ∼ Φ P grief ) between them (representing a synchronistic event). These correlations are experienced as meaningful by the subject insofar as it attributes grief-related content to them in its state Φ M grief . Likewise, any other archetypal pattern would manifest other kinds of synchronistic events related to its content and, thus, limit the range of possible subjective experiences. In this way, the attribution of meaning is always subjective – but it is never arbitrary.

This is not the end of the story though. As soon as the grief state Φ M grief appears consciously, it has a backreaction onto Φ P P N grief , which induces a perturbation of the archetypal grief pattern and its environment in the psychophysically neutral domain. This perturbation of Φ P P N grief can lead to a new equilibrium situation, a new unconscious homeostasis as it were, so that a slightly changed state Φ P P N grief ⁎ may create a novel state Φ P grief ⁎ and, thus, a novel correlation ( Φ M grief ∼ Φ P P N grief ) ⁎  – another synchronistic event.

In Jungian psychoanalysis, a dynamic like this can be therapeutically useful to overcome a difficult situation (here connected to grief) and even constructively exploit it to turn to an attitude more conducive for the process of self-realization, which Jung called individuation. Ultimately, it is the transformative impact of a meaningful coincidence that decides how significant it has been for the experiencing subject.^[33]

3.3 Exceptional experiences

The Pauli–Jung conjecture is not only conceptually appealing, but it also has wide-ranging empirical consequences – a promising feature that makes it particularly outstanding among several related approaches to mind–matter research, to be discussed in Section 4.

As indicated above, induced correlations can appear as coincidence phenomena and dissociation phenomena, above and below ordinary baseline correlations. Coincidence phenomena exhibit excess correlations above ordinary baseline correlations. They include meaningful coincidences (synchronicities in Jung’s parlance) that connect M and P more than ordinarily. Conversely, dissociation phenomena exhibit deficit correlations where ordinary baseline correlations are disconnected, e.g., in out-of-body experiences, sleep paralysis etc. Based on the Pauli–Jung conjecture, Atmanspacher and Fach proposed a taxonomy in which coincidence and dissociation phenomena form two of four fundamental types of exceptional experiences based on induced correlations.^[34]

As of today, about 3,000 cases of spontaneously occurring exceptional experiences have been systematically collected and evaluated at the Institute for Frontier Areas of Psychology (Freiburg).^[35] As a result of various factor analyses, cluster analyses, item analyses, and scale analyses, the taxonomy predicted by the Pauli–Jung conjecture turned out to be the most robust and best generalizable model for all analyzed samples. The fact that all patterns occur not only in subjects seeking help but also, although less often, in the general population shows that exceptional experiences are widespread and continuously distributed in their intensity and frequency.

One of the general population samples was compiled in cooperation with the Psychiatric University Clinic Zurich.^[36] After the standard, questionnaire-based procedure of identifying individuals according to the taxonomy, their behavior in psychophysical settings known as Mooney tasks was analyzed. With such tasks, the disposition of subjects to project meaningful objects into a random distribution of pixels can be studied. Wyss found that among the four basic types of exceptional experiences only subjects inclined toward coincidence phenomena showed a significant rate of false positives in the task.^[37] These subjects perceive meaningful excess correlations (patterns) in situations that are random by construction – impressive support for the taxonomy of phenomena not only for spontaneous occurrences but even in controlled experiments.

Moreover, applying the framework of the Pauli–Jung conjecture to the psychodynamics of situations in which subjects report exceptional experiences yields new and fascinating insights. Fach showed this for the interplay of bonding and autonomy for adolescents exhibiting exceptional experiences in their family contexts.^[38] In addition to a better understanding of the nature of mind–matter correlations in general, such psychodynamics studies offer specific intervention strategies with distinct therapeutic potential for subjects suffering from exceptional experiences.

However, far from all subjects reporting exceptional experiences suffer from them or even receive psychotic diagnoses. To avoid a premature and unjustified identification of exceptional experiences exclusively as mental disorders, the constructed questionnaires assess their phenomenology only, disregarding issues of veridicality or even psychopathology. The question of veridicality (or “truthfulness”) is delicate because it bears critically on assumptions about ontology. From a physicalist perspective, the veridicality of an experience requires that it must not contradict the laws of physics. If it does, the experience will likely be ditched as a psychopathological impairment or a hallucination, which, however, is still veridical from a phenomenological standpoint.^[39] From a dual-aspect perspective, correlational experiences ( Φ M ∼ Φ P ) are subject to neither physics alone nor psychology alone. To dismiss them as hallucinations because they do not follow the laws of physics would be an obvious category mistake.

The existing empirical material shows – plausibly – that the (self-rated) perceived intensity of induced exceptional experiences decreases as a function of increasing frequency. Subjects may report low-intensity, hardly meaningful experiences fairly often, while “once-in-a-lifetime-experiences” of almost existential, numinous quality are rare. Low-level intensity experiences exhibit a small difference from the baseline of no experienced meaning at all. This suggests the heuristic picture of a monotonic increase of the intensity of meaningful experiences with increasing | Δ ( M ∼ P ) | . Rather than treating singular events of high intensity as statistical outliers, they are here seen as part of a lawful regularity.

In a similar vein, the empirical material also shows that structural baseline correlations with Δ ( M ∼ P ) = 0 (such as psychosomatic or psychoneural correlations) are stable and reproducible as standard scientific methodology demands. Induced correlations, however, are less stable up to completely evasive, and they are difficult to reproduce up to completely irreproducible. Hence, we may imagine a continuum of stability and reproducibility as a function of | Δ ( M ∼ P ) | that looks heuristically like the diagram below. The higher the intensity of an experience (solid line) and its associated meaning is, the less stable and, as a consequence, the less reproducible (dashed line) it is to be expected. Or, somewhat sloppily speaking, the scientific aspiration to increase reproducibility inevitably entails that experienced meaning has no place in science.

There are immediately evident important lessons to be learned from these observations. The Pauli–Jung conjecture predicts a spectrum of reproducibility related to a continuum of the intensity of induced correlations, both depending on their distance | Δ ( M ∼ P ) | from the baseline of structural correlations. The higher the intensity of experienced meaning, the lower the reproducibility of the experience. However, reduced or lacking reproducibility as such should not be seen as a knee-jerk indicator for reduced or lacking scientific soundness. There are innumerable events that have not been and will never be reproduced, and no one doubts their factuality. The world of controlled laboratory experiments is certainly small compared to the world around us.^[40]

This is not a credo for some kind of hocus-pocus pseudoscience. Rather, it would be interesting to look at the spectrum of reproducibility as a scientific topic in its own right. We do already know that there are variations of reproducibility in established science, such as the deterministic reproducibility for individual events, statistical reproducibility for ensembles, problems with ensemble reproducibility in non-ergodic systems, long-time transients, and other situations eluding the straightforward application of limit theorems.^[41] It could be a valuable enrichment to science to study how reproducibility changes depending on circumstances rather than uncritically rejecting research based on reproducibility criteria not properly adapted to the context of the situation.

4.1 Implicate and explicate orders

Arguably the closest relative of the Pauli–Jung conjecture is Bohm’s proposal to consider the mental M and the physical P as decomposed explications (explicate orders) of holistic implicate orders whose most fundamental form he calls holomovement, resembling the unus mundus of Pauli–Jung.^[42] In between M and P and the holomovement, Bohm suggests a multilayered structure of implicate orders each of which generates explications that in turn may be implicate with respect to further explications.^[43] In this way, he refers to structures that resemble a hierarchy of archetypal patterns in the Pauli–Jung framework.

Pauli and Jung did not address anything akin to the relativity of the distinction between implicate and explicate orders. However, such a distinction is important to understand the interplay of ontic and epistemic domains in the nested hierarchy of levels of reality in their conjecture. As an implicate order can be explicate with respect to a more implicate order, an ontic level of reality can be epistemic with respect to a more ontic level. A more detailed discussion of such a relative onticity, adopted from Quine’s ontological relativity, would exceed the scope of this paper.^[44]

Manifestations of implicate orders into separate states Φ M and Φ P are called unfolding in Bohm’s framework, and backreactions from Φ M and Φ P to their underlying implicate order are called enfolding. While in the Pauli–Jung conjecture archetypal activity is always psychophysically neutral, i.e., archetypes are neither mental nor physical, Bohm refers to implicate orders that are both mental and physical,^[45] suggesting a distinction between M and P within such implicate orders. This “both-and” figure, as innocent as it may look, marks a grave deviation from the “neither-nor” of the Pauli–Jung conjecture. Taking it at face value, it points to a representation of implicate order states as product states in ℳ ⊗ P .

States of an implicate order in which both mental and physical properties are already separable would characterize a version of panpsychism – the view that mentality is fundamental and ubiquitous in the natural world.^[46] In this view, the index PPN (psychophysically neutral) would be illegitimate for such states. Rather, one might want to speak of product states Φ P P = Φ M ⊗ Φ P with PP for panpsychism. It is not clear whether Bohm wants to stretch his panpsychism eventually to the holomovement as the ultimate implicate order – if not, the holomovement state would be a non-product state Φ P P N ≠ Φ M ⊗ Φ P as all archetypal patterns in the Pauli–Jung conjecture are assumed to be.

An important point common to Bohm and Pauli–Jung is their emphasis on the significance of meaning, which no other approach to the mind–matter problem highlights so crucially (though Bohm, naturally, does not stress the subjective experience of meaning as much as Jung does). In Bohm’s wording, this is addressed by the notion of active information, which brings implicate structures into explicate forms. By doing so, not only separate states Φ M and Φ P are generated as explicate orders from an underlying implicate order, but in addition, active information deriving from the implicate order substantiates mind–matter correlations ( Φ M ∼ Φ P ) as meaningful. These correlations arise as a consequence of the fact that both Φ M and Φ P unfold together from the same state of the same implicate order.

Hiley, a close collaborator of Bohm for decades, developed the idea of implicate and explicate orders further using the formal apparatus of representations of algebraic structures. Picking up on earlier proposals by Eddington,^[47] he identified idempotents I of Clifford algebras as operators that leave the structural existence of a system invariant, though its concrete properties may well be subject to change. Irrespective of how much the appearance of a system may vary, the structural existence of its state remains preserved. Formally, this preservation is expressed by the relation I = I 2 (in the Hilbert space representation of ordinary quantum physics, idempotents become projection operators leading to the propositional lattices of standard quantum logic).^[48]

While these basic algebraic structures refer to implicate orders, their representation describes their manifestations as explicate orders of the mental and the physical domain. Specifying the general ideas laid out by Bohm and Hiley,^[49] Hiley successfully used (generally non-commutative) Clifford algebras to reproduce basic principles of known physics using representations of these algebras. In this reconstruction, the states of quantum systems are representations of elements of so-called ideals of the algebra, which are generated by idempotents.^[50]

That idempotents have eigenvalues 0 or 1 can now be interpreted in terms of logical propositions with truth values about the existence of states. If idempotents commute, existence is always well-defined: either a state exists or it does not exist. However, if idempotents do not commute, existence as such becomes difficult to define – a well-known matter of debate about ontic versus epistemic interpretations in the foundations of quantum physics. The process of measurement is a way of forcing unambiguous Boolean substructures to arise as explications of the implicate non-Boolean structure implied by non-commuting idempotents.^[51]

Other representations of the algebra, yet to be found, are hoped to be relevant for mental processes. As the basic algebraic structure is atemporal and aspatial, it is a promising candidate to characterize a pre-space and pre-time reality, implying that the holomovement must not be mistaken as a movement in time or in position space. Eventually, both the mental and the physical should be describable as manifestations, or representations, of that algebra.^[52] Since both representations derive from the same algebra, they are supposed to exhibit the mind–matter correlations ( Φ M ∼ Φ P ) that are at the core of the mind–body problem. Pylkkänen related Bohm’s and Hiley’s work to modern approaches in the philosophy of science, the philosophy of mind, and cognitive science.^[53]

4.2 Neutral monism

Another set of relatives to the Pauli–Jung conjecture can be found in the class of compositional dual-aspect thinking. The notion of neutral monism has been coined for this class, as exposed by its main historical protagonists Mach, James, and Russell. Stubenberg discusses its relations to other frameworks of thinking. Highlighting the influence of Russell, (a subclass of) it is also sometimes dubbed Russellian monism.^[54]

In compositional dual-aspect approaches, there are psychophysically neutral elements, neither mental nor physical, which can be composed into configurations producing larger entities. Depending on the configuration of the composed entity, its state acquires mental or physical properties. In this sense, Φ P P N denotes the states of psychophysically neutral elements rather than of a psychophysically neutral whole. States Φ M and Φ P would figure as macrostates emerging from the neutral microstates.

This is the conception that one reads in Russell’s Analysis of Mind where he sees the “neutral stuff” as neither mental nor physical: “both mind and matter are composite, the stuff of which they are compounded lies […] above them both, like a common ancestor.”^[55] A few pages down he refers to neutral monism in terms of some raw material of which “some arrangements may be called mental, while others may be called physical.”^[56] Here, Russell’s compositional (atomistic) move is obvious – in contrast to the decompositional (holistic) structure in Bohm and Pauli–Jung.

How are the neutral elements themselves to be characterized? Here, Russell refers to the notions of sensations and perceptions^[57] – which has caused some confusion among his interpreters. Although he makes efforts to clarify that he does not think of both in terms of subjective experience, these notions sound much like phenomenological or even subjective idealist. In his Analysis of Matter, Russell changes the terminology by moving to the more neutral notion of events and sticks to that later on.^[58] And in a late article of 1956, Russell clearly rejects panpsychism, as lifeless objects “move and undergo various transformations, but they do not ‘experience’ these occurrences.”^[59]

The two other protagonists of neutral monism in the late 19th century were Mach, originally a physicist, and James, originally a psychologist. Both share with Russell the compositional structure of mental states Φ M and physical states Φ P out of neutral elements in states Φ P P N that are neither mental nor physical. Interestingly, similar kinds of misunderstandings as for Russell have been prompted by Mach’s usage of sensations and James’s usage of pure experience when referring to the psychophysically neutral. But, as for Russell, neither of them subscribes to subjective idealism.

James does even categorically disavow any ontological significance for consciousness and explains his notion of pure experience as a “plain, unqualified actuality, or existence, a simple that.”^[60] If one still wants to understand this as non-neutral, one should prefer to resort to objective rather than subjective idealism, a universal mode of presence underlying all mental and physical appearances. Other, selected versions of objective idealism are sketched in Section 4.3.

Alternative to the neither-nor figure of psychophysical neutrality in traditional neutral monism, the states of the base elements can be considered both mental and physical. A pertinent example is naturalistic dualism according to Chalmers,^[61] where the base states have both internal phenomenal properties ( Φ M ) and external physical properties ( Φ P ) . Insofar as any base state has mentality as an internal property, mentality is fundamental and ubiquitous – as in panpsychism. Naturalistic dualism is a dual-aspect model in which the two aspects appear at the same level as the base states of which they are aspects. Such a panpsychist ontology suggests that the base states are product states Φ P P = Φ M ⊗ Φ P . (A more radical panpsychist reading of Russellian monism holds that consciousness in some primitive form is the non-structural categorical ground that drives all structure, its intrinsic nature as it were.)

A special feature in naturalistic dualism, anticipated by Sayre,^[62] is that the base elements as such are conceived as states of pure information. Pure here indicates that this information is conceived as purely syntactic (in the sense of Shannon) and any reference to meaning is rejected. Such information states require distinctions in their state space (such as Weizsäcker’s ur-alternatives), which are needed to define syntactic information. This in turn implies a context-independent primitive partition of that state space, perhaps with the one constraint that the mental and physical aspects of so defined information states mesh with each other in the right way.

4.3 Objective idealism

Another relative of the Pauli–Jung conjecture, sharing a number of features with it, is objective idealism.^[63] This position fell largely out of fashion with the rise of physicalism, though there are research programs in its spirit even today, such as Hoffman’s (compositional) approach using conscious agent networks.^[64] Since it is impossible in this outline to sketch objective idealism anywhere close to its full comprehension, only a few exponents will be indicated, from both Western and Eastern background. These are Schelling’s philosophy at the turn of the 19th century and the much more ancient Indian systems of Advaita Vedanta and the Yoga Sutra by Patanjali.^[65]

Schelling, starting off as a follower of Fichte, was decidedly more concerned about the results of the developing sciences than his teacher. He realized soon that Fichte’s subjective idealism with its emphasis on the ego is too narrow and too one-sided. Turning back to Spinoza, he explored the idea that mind and matter (spirit and nature) are two sides of a primordial totality – a base reality conceived as a higher unity beyond the mind–matter distinction.^[66] Schelling’s famous quote “Nature should be made Mind visible, Mind the invisible Nature” takes mind-nature dualism as a cognitive move for the sake of discursive thinking, but he rejects this as a metaphysical option.^[67]

His next step was to posit the primordial reality without space and time as a dynamic, undifferentiated unity of the absolute-ideal (subjectivity) and the absolute-real (objectivity) in an “eternal act of absolute reason” from which mind and nature are decomposed as separate forms. Reality as such is a dynamic self-organizing activity indifferent with respect to even the most fundamental opposition of subject and object. This indifference – later referred to as the “unground” in his freedom essay^[68] – points to states Φ P P N ≠ Φ M ⊗ Φ P , which are neither mental nor physical. The highest law of absolute reason at this level is the law of absolute identity, an identity whose only predicate is that it has no predicates. This is the core of his objective idealism.^[69]

Schelling’s “system of identity” offers a delicate balance of the mental and the physical as forms of manifestation.^[70] Its perfect symmetry is the same as in the Pauli–Jung conjecture, although Schelling’s system does not, at least not explicitly, include a backreaction from mind and matter to their basis. This backreaction is crucial for Pauli and Jung, as it enables induced mind–matter correlations. Schelling does not explicitly address such correlations, but he talks about a “transitive being” that links mind and matter as predicates emerging from the indifferent “unground.” And he is astonishingly clear about the necessarily noncausal nature of this link.^[71]

Rejecting the mind-like structure of Fichte’s ego, Schelling downgrades the mental to a derivative aspect and insists on an ultimate reality as a tertium quid that is indifferent with respect to the mind–matter distinction. On the other hand, Schelling at times also seems to think about the base reality as both mental and physical, similar to a panpsychist attitude, Φ P P = Φ M ⊗ Φ P .^[72] With both versions, he departs from basic tenets usually ascribed to German idealism. Other than for Pauli and Jung who mostly reject epistemic access to the unus mundus, Schelling’s ultimate and absolute reality can be apprehended by “intellectual intuition” (a Spinozist term) – not to be conflated with intellect as a rational cognitive capacity.

The late Schelling, in his struggle to achieve a better understanding of the absolute, resorted to Neoplatonic and mystic ideas, very much akin to what Jung did with his recourse to alchemy and the Hermetic tradition, which have their origin in the Near and Middle East. This makes it interesting to look into the objective idealism of Indian spiritual traditions and compare them with the Pauli–Jung conjecture. One of these traditions was recently investigated by Whitney in a thoughtful comparison with Jung’s analytical psychology:^[73] Patanjali’s Yoga Sutra, dating back to the first centuries AC.

A key clarifying ingredient of Whitney’s presentation of the Yoga Sutra is the distinction between two orientations of consciousness: consciousness in its true nature as orientation A and consciousness assuming the modifications of mind as orientation B. Other notions for orientation A are “pure consciousness,” “pure subjectivity,” or “consciousness as such” (purusa): Φ C C (CC for cosmic consciousness). Consciousness in orientation A is unchanging, immutable, eternal, self-knowing – and non-dual, which is to say that it is free from distinctions. By contrast, consciousness in orientation B refers to states Φ M of our everyday consciousness: perception, cognition, emotion, and other more or less subtle contents of the discriminating mind – “consciousness for us” (prakrti).

This framework of thinking is a kind of cosmic objective idealism in which the cosmic mind, orientation A, is open to human experience, if appropriate practices are conducted successfully. The difference between orientations A and B is created by avidya, ignorance, characterized by change, egoism, impurity, attraction, aversion, fear, suffering, and confusion. However, precisely since orientation B can change, it can in principle become aligned with the unchanging eternal orientation A.

A striking similarity between Patanjali and Jung is their distinction of ego and self. In Patanjali’s account, the former is a construct of the mind and the latter a mode of pure consciousness, sometimes referred to as atman. Although the ego is considered as one of the great afflictions within orientation B, it may nevertheless change so as to get aligned with orientation A and, thus, accomplish liberation. Note, however, that masquerading A with the tools of B is not the same as experiencing A directly! Likewise, Jung’s notion of the ego is the conscious manifestation^[74] of an archetypal self, which is the goal of the process of individuation.

While for Patanjali it is avidya that blocks the road from prakrti to the pure consciousness of purusa, analytical psychology proposes an increasing “opacity” of the unconscious as the obstacle precluding access to the ultimate ground of the undivided unus mundus. How could an “opacity of the unconscious” be interpreted in detail? In Jung’s account, it is the loss of distinctions as tools for differentiation that is required for prakrti. This loss of distinctions implies a loss of “speakability” or “effability,” a loss of discursive cognition. As soon as the ultimate distinction dissolves, the resulting undivided reality does not leave any discursive option – non-duality par excellence.

The neo-Kantian flavor of Jung’s and Pauli’s approach did not permit them for a long time to think about this non-dual reality as being epistemically accessible. Only on the last pages of his final opus Mysterium Coniunctionis, Jung took the possibility of such an access seriously – literally as an act of revelation.^[75] However, immanent experiences like this (a notion adopted from Deleuze) cannot be subjective experiences in the ordinary, profane sense. Along the lines of the Pauli–Jung conjecture, one ought to think about them as experiences of a neutral reality (neutral psychophysically and neutral with respect to all other distinctions, including that of subject and object), thus avoiding the objective idealist notion of “pure consciousness.”

One advantage of this move is that the term “pure consciousness” makes it too easy to be mistaken as subjective, as in James’s “pure experience” or Russell’s and Mach’s “sensations” (see Section 4.2). This is avoided by a less biased term such as “neutral reality.” Another, more important issue is that Patanjali analyzes the cosmic idealism of “pure consciousness” states Φ C C in orientation A primarily in relation to its mental manifestations Φ M in orientation B. Physical manifestations Φ P remain largely unaddressed in his account, and the mental–physical connection ( Φ M ∼ Φ P ) is even less explained. By contrast, the neutral reality in the Pauli–Jung conjecture has an explicit relation to both the mental and the physical: both are manifestations of the neutral Φ P P N . This entails three benefits with remarkable potential for concrete research and further insight.

1. Starting from the psychophysically neutral offers the option to explore formal structures for the description of the mental that are already well established for the physical. Since both arise from the same neutral ground, one would expect that key features in the description of the two domains should be isomorphic. One of these features is non-commutative structures in physics and psychology, a novel research program that has been attracting ever more scientists worldwide for the past two decades.^[76]

2. The Pauli–Jung conjecture and its ramifications provide a most natural and straightforward characterization of correlations between the mental and the physical. Decomposing a holistic state into parts generically leads to correlations between the parts. This means that a decompositional dual-aspect framework implies such correlations in the first place; there is no need to look for post hoc rationalizations for them and also no need to declare them as mysterious. In fact, a taxonomy of psychophysical correlations deriving from the Pauli–Jung conjecture is now largely supported by a comprehensive stock of empirical material.^[77]

3. More generally, cosmic idealism bears the risk of embodied life, both mental and physical, being devalued relative to pure consciousness. Jung lends a dignity and sense of meaning to creation and human life,^[78] which becomes somewhat overshadowed by models conceiving human consciousness as mere ignorance or at best as something that can be aligned with pure consciousness and thereby be transcended. As cogently argued by Main, Jung’s emphasis can be understood by the panentheist thought that the divine creator needs feedback from his creation to become conscious himself.^[79]

Together with the Yoga Sutra, another widespread and influential Hindu-related spiritual tradition is Advaita Vedanta, mainly due to Shankara (a.k.a. Sankara or Samkara) around 800 AC. While the Yoga Sutra especially focuses on the psychological side of the path toward liberation, Advaita Vedanta talks about both mind and world more symmetrically. A particularly informative and compact introduction to its main philosophical ideas is due to Deutsch.^[80]

On the side of physical nature, the outside world, Advaita Vedanta suggests a procedure of “sublation” (badha) that can be applied to a hierarchy of levels of being. To sublate some experience of an object (e.g., of a material thing) means, roughly, to replace the experience by another one due to fresh insight. Sublation is a tool to distinguish appearance from reality (understood as the ultimate reality): while appearances can be sublated by other experiences, reality cannot be sublated by any other experience.^[81] The unreal, a third category next to appearance and reality, is that which neither can nor cannot be sublated by other experiences – such as a circular square or other oxymorons.

Three types of appearances can be characterized by sublation: the “real existent,” the “existent,” and the “illusory existent.” The real existent comprises those experiences that can only be sublated by the ultimate reality itself. These are spiritual experiences that are only sublatable by transcending the subject–object distinction.^[82] The existent comprises experiences that can be sublated by the real existent and by ultimate reality. The vast majority of everyday perceptual, cognitive, and affective experiences belong to this type. The illusory existent comprises experiences that can be sublated by all other types of experiences: hallucinations, erroneous sense perceptions, and dreams. While the illusory existent is epistemically empty, the unreal is ontically empty.

The overarching idea of Advaita Vedanta is for its adherents to analyze all experiences and sublate them until they cannot be sublated any further, i.e., until the ultimate reality is reached. In other words, this means to move through successive levels of appearance with the goal of arriving at the most fundamental level: the ultimate reality of the brahman. Its experience is non-dual and unveils the delusional, avidya-conditioned multiplicity of appearances in the physical world. Yet, this world can be made intelligible discursively by employing avidya and by reversing sublation: moving back from the one to the many.

On the side of the mind, Advaita Vedanta distinguishes four classes of states Φ M of consciousness: the wake state of the ordinary conscious mind, the dream state, the state of deep sleep, and transcendental consciousness. While wake and dream states are already targets of contemporary consciousness studies, deep sleep only slowly becomes lifted from unconscious activity to a state of consciousness.^[83] In Advaita Vedanta, experiences of deep sleep still retain a knowing subject but all objects of consciousness are gone, and distinctions are experienced as pure potentialities (thus revealing the nature of avidya).

As far as transcendental consciousness is concerned, there are two distinct modes of it:^[84] a borderline experience (savikalpa samadhi) at the transition from deep sleep and a pure experience of reality (nirvikalpa samadhi). Different from deep sleep itself, borderline experiences are experiences of the presence of non-dual reality, with neither object nor subject but still representational. The stage of transcendental consciousness culminates in the pure experience of non-dual reality directly. To put it succinctly, in borderline experiences there is awareness of non-dual reality; in pure experience, non-dual reality is no longer an object of awareness – it just is.^[85]

The pure experience of reality is the ultimate realization of the atman in which it merges with the brahman, so that their distinction, the most fundamental one, becomes lifted. In Advaita Vedanta, to affirm oneself as reality is the act of a free human. In Patanjali’s account, this is a state in which consciousness B becomes aligned with consciousness A, in which all avidya collapses as all distinctions are gone. Likewise, realizing the archetype of the self in Jungian terms is the goal of the process of individuation, in which the conjunction with the unus mundus is accomplished.

As Advaita Vedanta can be phrased in terms of successive stages of consciousness terminating in a state of cosmic consciousness Φ C C , it is tempting to classify this state in terms of objective idealism. This is consolidated by the fact that even on the physical side, the targets of discussion are not physical objects and their relations but experiences of those objects and relations. However, insofar as an experience of non-dual reality is explicitly beyond the mind–matter and subject–object distinction, Advaita Vedanta also shares an essential feature of a psychophysically neutral reality: Φ P P N ≠ Φ M ⊗ Φ P . Or, at least, one might submit that more than traces of the psychophysically neutral stand out.