Synchronicity

What it is

Carl Jung's term for coincidences that are meaningfully but not causally connected — where an inner state and an outer event correspond in a way that feels significant, and no mechanism connects them.

His claim was not that such events are striking. It was that they constitute evidence for an acausal connecting principle: an ordering of the world that operates alongside causality rather than through it, in which meaning itself can be a link between events.

The illustrative case is Jung's own. A patient whose rationalism was blocking her analysis recounted a dream of being given a golden scarab. As she spoke, Jung heard tapping at the window, opened it, and caught a rose-chafer beetle — the nearest local analogue to a scarab. He handed it to her. The analysis, he reported, moved after that.

Where it came from

Jung used the term from the late 1920s and set it out fully in Synchronicity: An Acausal Connecting Principle (1952), published in a volume alongside an essay by Wolfgang Pauli on Kepler's archetypal thinking.

The Pauli connection is genuine and is regularly either overstated or dismissed. Pauli — Nobel laureate, author of the exclusion principle, one of the founders of quantum mechanics — was Jung's patient and then his correspondent over more than two decades, and the two collaborated on the idea seriously. Pauli was interested in whether the conceptual upheavals of quantum theory implied something about the relationship between mind and matter.

What that establishes is that a first-rate physicist took the question seriously. It does not establish that physics supports the conclusion, and Pauli's own formulations were considerably more tentative than the use later made of them.

How it is used

Synchronicity is the standard modern justification for divination, and it is what allows a practitioner to answer the obvious objection.

If shuffled cards are random, how can they mean anything? The synchronistic answer: the cards are not causally connected to your situation, and do not need to be. The moment of the reading has a character, and everything occurring in that moment — the cards that fall, the hexagram thrown, the sky overhead — expresses it. Meaning, not causation, is the connection.

Jung's foreword to the Wilhelm/Baynes I Ching is where this reached a mass audience, and it is probably the single most influential thing he wrote for the popular spiritual world.

What we can and cannot say

We can say the experience is real, common and psychologically significant. People do have coincidences that strike them as meaningful, sometimes at turning points, and the experience can be genuinely consequential regardless of its cause.

We can say the ordinary explanation is strong and does not require anyone to be credulous. Three components do most of the work:

Apophenia. Pattern-detection runs constantly and errs toward false positives, because historically the cost of missing a real pattern exceeded the cost of seeing a spurious one.

The law of truly large numbers. With enough events, extremely unlikely ones become certain. The mathematician J.E. Littlewood formalised a version of this: given the number of discrete events a person experiences while awake, a "one in a million" occurrence should be expected at a rate of roughly one a month. Coincidences at that level are not anomalies; they are the schedule.

Selective recall. The coincidences that mean something are remembered and retold. The vastly larger number of dreams about beetles that were not followed by beetles are not recorded at all, by anyone, ever. There is no denominator.

We can say the theory is not falsifiable as stated. Jung offers no way to distinguish a genuine synchronistic event from a striking coincidence, no measure of the effect, and no prediction that could fail. That is a serious problem for a claim presented as a principle of nature on a par with causality.

We can say the quantum framing is misused. Entanglement is a specific, measurable correlation between prepared particles that cannot transmit information, and it has no bearing on beetles at windows. Pauli did not claim otherwise.

We cannot say the experiences do not matter. Jung's clinical interest was in what the event meant to the patient and what it unlocked, and on that ground he may well have been right about the scarab without being right about the universe. A great deal of what this site covers has that shape: a real effect, and an explanation for it that is doing no work.

Further reading

• C.G. Jung, Synchronicity: An Acausal Connecting Principle (1952).
• Arthur I. Miller, 137: Jung, Pauli, and the Pursuit of a Scientific Obsession (2009) — on the collaboration, fair to both.
• David Hand, The Improbability Principle (2014) — the mathematics of why extraordinary coincidences are ordinary.