Science · Mind

What Is Synchronicity?

Jung’s “meaningful coincidence”, and what probability says about it.

The question

When a coincidence feels meaningful, is something more going on?

The short answer

Carl Jung called meaningful coincidences “synchronicity” and proposed they had an acausal connection. Probability shows that striking coincidences are expected in a big enough world; whether they mean anything is a question for philosophy, not measurement.

23 people: 50.7% 50% 60 people Chance two share a birthday
In a group of just 23 people, the chance that two share a birthday passes 50%. Coincidences are far more common than intuition expects.

What science knows

Historical Fact

Jung set out the idea in a 1952 essay published alongside work by the physicist Wolfgang Pauli. His famous example: a patient describing a dream of a golden scarab as a similar beetle tapped at the window.

The pattern

Established Mathematics

The birthday problem shows how quickly coincidences add up: with 23 people, a shared birthday is more likely than not; with 70, it is over 99%. The statisticians Persi Diaconis and Frederick Mosteller called this the law of truly large numbers: with enough chances, the outrageous becomes likely.

What is still uncertain

Mixed Evidence

Synchronicity as an acausal principle has no experimental support, and it is hard to see how it could be tested. Psychologists study why some people experience coincidences as more meaningful than others.

Why humans find it interesting

Cultural Tradition

The idea resonates because meaning is personal: the same coincidence can be noise to one person and a turning point to another.

CUE perspective

CUE Perspective

CUE is interested in synchronicity as experience, not evidence. A coincidence that makes you pause is an invitation to reflect.

The maths keeps that honest: coincidences are common, and what you do with one is up to you.

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Sources

  • Jung, “Synchronicity: An Acausal Connecting Principle”, in Jung & Pauli, The Interpretation of Nature and the Psyche (1952; English 1955)
  • Diaconis & Mosteller, “Methods for studying coincidences”, Journal of the American Statistical Association 84 (1989)
  • Hand, The Improbability Principle (Scientific American / Farrar, Straus and Giroux, 2014)

Written by CUE from the sources above. Some topics were suggested by Polymath; its claims are not reproduced.