The acausal principle occupies a pivotal and contested position in the depth-psychology corpus, functioning simultaneously as an epistemological challenge to Newtonian determinism, a psychological hypothesis about meaningful coincidence, and a proto-cosmological claim about the structure of reality. Its canonical formulation appears in Jung's 1952 monograph Synchronicity: An Acausal Connecting Principle, where causality's statistical limitation in microphysics opened conceptual space for positing a second, complementary principle governing the simultaneous occurrence of meaningfully connected events. Jung and, with greater systematic rigor, von Franz distinguish two registers of the acausal: the narrower phenomenon of synchronistic events—isolated coincidences between psychic states and external occurrences—and the broader category of acausal orderedness, encompassing a priori mathematical structures, radioactive half-lives, and the constancy of the speed of light, none of which admit causal derivation. Hoeller traces the intellectual genealogy of this shift, noting that quantum physics and relativity, not philosophy or theology, first cracked the absolute validity of causal law. Clarke situates the principle within Jung's cross-cultural dialogue with Eastern thought, particularly the I Ching, where an orderedness-through-meaning rather than mechanism had long been assumed. The central tension in the corpus runs between treating acausality as a strictly formal placeholder for unexplained correlation and investing it with ontological weight as evidence for the unus mundus. Von Franz and Stein press furthest toward the cosmological reading; Jung himself maintains cautious empiricism. The principle's relationship to archetype, number theory, parapsychology, and the psychoid layer of reality gives it unusual scope across the library.
if the connection between cause and effect turns out to be only statistically valid and only relatively true, then the causal principle is only of relative use for explaining natural processes and therefore presupposes the existence of one or more other factors
Jung's foundational argument that the statistical character of natural law in modern physics logically necessitates a supplementary, non-causal principle of explanation.
, The Structure and Dynamics of the Psyche, 1960thesis
the possibility of an acausal principle connecting events in time would have appeared a total impossibility... it was not philosophy or religion or even psychology, but rather the physical sciences themselves that shattered the absolutism of the causal principle
Hoeller argues that it was the internal development of physics—quantum mechanics and relativity—rather than any external critique, that demolished absolute causality and made an acausal principle scientifically credible.
, The Gnostic Jung and the Seven Sermons to the Dead, 1982thesis
synchronistic phenomena in terms of the simple actuality or suchness of a contingence that cannot be reduced any further, that is, in terms of an acausal modality
Von Franz defines the acausal modality as irreducible contingency, arguing that language's causal structure obscures the genuine ontological novelty of synchronistic phenomena.
, Psyche and Matter, 2014thesis
Synchronicity, or 'acausal orderedness,' is a principle underlying cosmic law. 'Into this category come all acts of creation, a priori factors such as the properties of natural numbers, the discontinuities of modern physics, etc.'
Stein presents Jung's expanded, cosmological reading of the acausal principle, in which human synchronistic experience becomes a special case of a universal ordering principle.
, Jung's Map of the Soul: An Introduction, 1998thesis
acausal orderedness means that certain factors in nature are ordered without its being possible to find a cause for such an order. Within the realm of matter this would be such facts as the time rate of radioactive decay, or the fact that the speed of light is 186,000 miles per second
Von Franz defines acausal orderedness as the broader category encompassing both physical constants and mathematical necessity, of which synchronistic events are only particular, time-bound instances.
, Psyche and Matter, 2014thesis
the wider conception of synchronicity as an 'acausal orderedness.' Into this category come all 'acts of creation,' a priori factors such as the properties of natural numbers, the discontinuities of modern physics
Von Franz, quoting Jung directly, argues that the narrow definition of synchronicity must be expanded toward a general acausal orderedness that subsumes reproducible physical and mathematical phenomena.
, Psyche and Matter, 2014thesis
in addition to the principle of causality, it was necessary to postulate a parallel principle to account for the simultaneous occurrence of meaningfully connected events. He called this 'synchronicity'
Clarke narrates Jung's initial motivation for the acausal principle: the inadequacy of causality alone to account for meaningful coincidences encountered in clinical practice and confirmed by contact with quantum physics.
, Jung and Eastern Thought: A Dialogue with the Orient, 1994supporting
contemporary physicists also generally speak of an acausal connection... four newly discovered states of affairs that are currently considered acausal and that correspond to Jung's notion of acausal orderedness
Von Franz marshals independent astrophysical evidence—including radioactive half-lives, quantum unpredictability, the cosmic background, and the Foucault pendulum—to corroborate Jung's concept of acausal orderedness.
, Psyche and Matter, 2014supporting
The science of the I Ching is based not on the causality principle but on one which—hitherto unnamed because not familiar to us—I have tentatively called the synchronistic principle
Jung introduces the synchronistic principle as the unnamed, alternative ordering principle underlying the I Ching, distinct from and parallel to causality.
, The Spirit in Man, Art, and Literature, 1966supporting
synchronistic events should be taken as 'just-so' facts, as irreducible contingencies... synchronicity in the narrow sense is only a particular inst[ance of a more general principle of acausal orderedness]
Von Franz follows Jung in treating synchronistic events as irreducible contingencies that are special instances of the broader acausal orderedness governing natural numbers and physical discontinuities.
, Psyche and Matter, 2014supporting
mathematics deals with the 'acausal orderedness' in our own mind, which is based on number; and physics, among other themes, deals with the 'acausal orderedness' in nature, such as the speed of light and the rate of radioactive decay
Von Franz draws a parallel between the acausal orderedness of mathematical necessity in mind and that of physical constants in nature, suggesting a unified structural principle.
, Psyche and Matter, 2014supporting
This form of orderedness differs from that of the properties of natural numbers or the discontinuities of physics in that the latter have existed from eternity and occur regularly, whereas the forms of psychic orderedness are acts of creation in time
Von Franz distinguishes synchronistic acausal orderedness from the eternal, regular acausality of mathematical and physical constants by characterizing it as creative, time-bound occurrence.
, Psyche and Matter, 2014supporting
if the causal principle is only relatively valid, then... there must still remain a number of cases which do not show any causal connection. We are therefore faced with the task of sifting chance events and separating the acausal ones from those that can be causally explained
Jung outlines the methodological challenge arising from relative causality: distinguishing genuinely acausal events from those whose causes are merely unknown.
, The Structure and Dynamics of the Psyche, 1960supporting
We must of course guard against thinking of every event whose cause is unknown as 'acausal.' This, as I have already stressed, is admissible only when a cause is not even thinkable
Von Franz transmits Jung's critical caveat that acausality is a disciplined, last-resort designation, not a catch-all for unexplained phenomena.
, Psyche and Matter, 2014supporting
Only the great Arab philosopher Ibn 'Arabi tried to give a purely acausal description of such events, though he still postulates the idea of God as prima causa
Von Franz identifies Ibn 'Arabi as a pre-modern thinker who approximated an acausal description of coincident phenomena while still retaining a theological first cause.
, Psyche and Matter, 2014supporting
The primitive as well as the classical and medieval views of nature postulate the existence of some such principle alongside causality... in the course of the eighteenth century, it became the exclusive principle of natural science
Jung historicizes the acausal principle, noting that pre-modern correspondence theories implicitly recognized it before Enlightenment science collapsed all explanation into strict causality.
, The Structure and Dynamics of the Psyche, 1960supporting
they supposed that the same living reality was expressing itself in the psychic state as in the physical... the two sages devised a method by which an inner state could be represented as an outer one and vice versa
Jung locates the acausal principle in the ancient Chinese hypothesis of unity between psychic and physical reality, which underlies the I Ching's divinatory logic.
, The Structure and Dynamics of the Psyche, 1960supporting
events of this kind cannot be considered from the point of view of causality, for causality presupposes the existence of space and time in so far as all observations are ultimately based upon bodies in motion
Jung argues that precognitive experiments render energy-based causal explanation impossible, thereby requiring an acausal framework for time-transgressing psychological phenomena.
, The Structure and Dynamics of the Psyche, 1960supporting
Synchronicity: An Acausal Connecting Principle 63, 96, 198
Clarke's index entry confirming the centrality of Jung's monograph to his dialogue with Eastern thought, situating the acausal connecting principle within discussions of the I Ching and Taoism.
, Jung and Eastern Thought: A Dialogue with the Orient, 1994aside
Those sceptical of Jung's revival of the concept of the unus mundus may ponder the implication of reports... of experiments which seem to substantiate
Samuels briefly invokes experimental physics as contemporary corroboration for Jung's unus mundus, the ontological corollary of the acausal principle.
, Jung and the Post-Jungians, 1985aside
The archetype then, when manifesting in a synchronistic phenomenon, is truly awesome if not outright miraculous—an uncanny dweller on the threshold. At once psychical and physical
Hoeller characterizes the archetype's role in synchronistic events as the bridge between psychic and physical registers, illuminating the experiential dimension of the acausal principle.
, The Gnostic Jung and the Seven Sermons to the Dead, 1982aside