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Meaningful Coincidences, Serendipity, and Synchronicity

Contrasting and comparing their histories, definitions, and uses.

A coincidence is a remarkable conjunction of two or more incidents without an obvious causal connection between them. The word coincidence attracts two kinds of adjectives. One group implies no cause. These include: coincidental, mere, only, pure, true, sheer, and just. The other group implies that there might be a cause: meaningful, remarkable, and amazing.

Throughout human existence, the mystery of coincidences, the possibility of discoverable causes, has fueled human curiosity. Coincidences can offer clues to how reality works (Johansen and Osman, 2015) because they can be hints of explanations not yet considered.

The 19th-century philologist H.E. Shepherd traced the origins of the words coincide and coincidence. They probably began in Medieval Latin and then passed into the vocabulary of scholarly English writers during the first half of the 17th century, before being taken up by mathematicians during the great revival of mathematical study at that time in England. The words seemed to come into English through philosophy, having been translated from Roger Bacon’s Latin or from the Latin of some other philosophical writers of that time (Shepherd, 1880).

Coincidence became a household word in American English following the simultaneous deaths of Thomas Jefferson and John Adams on July 4, 1826. The pair died exactly 50 years after each had signed the United States Declaration of Independence (Shepherd, 1880). They died in different places: Jefferson in Charlottesville, Virginia, and Adams in Quincy, Massachusetts.

The U.S. president at that time was Adams's son John Quincy, who called the coincidence of their deaths on the nation's anniversary "visible and palpable remarks of Divine Favor" (Meacham, 2012 p. 496).

Two primary categories

The primary categories of coincidences include serendipity and synchronicity.

Serendipity: These are happy accidents. Horace Walpole, a member of the British House of Commons in the 18th century, recognized in himself a talent for finding what he needed just when he needed it. Walpole first coined the term serendipity in a letter to his friend and distant cousin Horace Mann, the British minister in Florence, Italy, on January 28, 1754 (Merton & Barber, 2004).

Walpole based the word on a fairytale entitled “The Travels and Adventures of Three Princes of Serendip.” Serendip is an ancient name for the island nation Sri Lanka off India’s southern coast. The king of the fable recognized that education requires more than learning from books, so he sent his sons out of the country to broaden their experience. Throughout the story, the clever princes carefully observed their surroundings and then used their knowledge in ways that saved them from danger and death (Merton and Barber, 2004).

Serendipity relies on the intersection between wisdom and chance to accidentally find something of interest or value. The intentions behind the activity taking place at the time of the unexpected observation or event are only indirectly related to the outcome (Copeland, 2019). There are two variations: 1) looking for something and finding it in an unexpected way, and 2) looking for something and finding something entirely different and very useful. Fleming’s discovery of penicillin is an example of looking for something and finding it in an unexpected way.

Synchronicity: Carl Jung (Jung, 1973) stimulated imagination about meaningful coincidences with his ideas about synchronicity as an acausal connecting principle. Acausal connections involve mechanisms different from cause leading to effect. Jung placed special emphasis on the role of archetypes in creating meaningful coincidences. He was influenced by the burgeoning field of quantum mechanics through Nobel Prize winner Wolfgang Pauli, as well as ancient Chinese philosophy and the theory of seriality as proposed by Viennese biologist Paul Kammerer (Townley and Schmidt, 1994).

Jung invented this term, which means "falling together in time," to explain meaningful coincidences. Synchronicity, as an acausal connecting principle, suggests that the shared meaning between two low-probability events had something to do with explaining why they happened. The word has become synonymous with meaningful coincidences. Jung’s descriptive definition of the meaningful coincidences explained by the synchronicity principle included coincidences that facilitate individuation, the process of spiritual and psychological development (Jung, 1973). The famous scarab story represents the individuation form.

Comparing and contrasting serendipity and synchronicity

Each is a form of meaningful coincidence. Each usually involves a mental event surprisingly matching an objective event in a potentially useful way. They differ in that serendipities usually have practical external world outcomes while many synchronicities are valued for their psychological and emotional impact.

Students of serendipity tend to be satisfied with luck or accident as explanations, while students of synchronicity tend to use these events to explore or justify explanations beyond conventional scientific principles. Serendipity explanations could be broadened to include unconventional explanations. Synchronicity explanations need to include conventional science principles.

Regarding predisposing factors, practically-minded serendipity researchers are developing ways to increase the probability of serendipity events. Synchronicity researchers tend to be satisfied with letting them happen with little attention to the predisposing factors. Synchronicity researchers could learn from serendipity researchers about how to train people to increase synchronicities.

Continuing dialogue between serendipity researchers and synchronicity researchers will enhance our understanding of each and broaden our understanding of meaningful coincidences.


Johansen, M. K., & Osman, M. (2015). Coincidences: A fundamental consequence of rational cognition. New Ideas in Psychology, 39, 34-44.)

Shepherd, HE (1880) The History of Coincide and Coincidence. The American Journal of Philology, Vol. 1, No. 3 p. 273-4

Meacham, Jon (2012). Thomas Jefferson: The Art of Power. New York: Random House p. 496

Merton, R. K. & Elinor Barber, E. (2004). The Travels and Adventures of Serendipity. Princeton, NJ: Princeton Press.

Copeland, S (2019) On serendipity in science: discovery at the intersection of chance and wisdom. Synthese 196:2385–2406

Jung, C (1973) Synchronicity. Princeton. Princeton University Press

Townley J, Schmidt R (1994) Paul Kammerer and the Law of Seriality in Fortean Studies edited by Moore S , London: John Brown p, 251-260)