Synchronicity: Jung's meaning and what the data say

Synchronicity is the name Carl Jung gave to the coincidence in time of two or more events that do not cause each other and that have, for the person living them, the same or a similar meaning. Both conditions count: no cause linking the events, and meaning. That is what Jung's 1952 essay says, which I read in its 1955 English edition, together with Paul Kammerer's 1919 book on “series” of coincidences, which Jung discusses.¹² The previous article was about what happens when many people coincide at once; this one is about the smallest coincidence, the one that happens to a single person, and what could be tested about it. What I did not read, I say at the end.

What does synchronicity mean, according to Jung?

Jung defines it in a sentence worth reading slowly: it is "the simultaneous occurrence of a certain psychic state with one or more external events which appear as meaningful parallels to the momentary subjective state".¹ It is not the same as synchronism, which only says that two events happen at the same time: synchronicity also asks that they be "causally unrelated events which have the same or a similar meaning".¹ And "acausal" does not mean that each event has no cause: Jung writes that "it is obvious that each event must have its own causality". What is missing is a common cause.¹

According to Wikipedia, the word came out of Jung's contact with the I Ching and a 1930 memorial address for Richard Wilhelm, translator of Chinese; in the foreword of 1952, Jung says he had been alluding to the phenomenon for twenty years without discussing it further.¹³ And he presents it as a hypothesis: "a hypothetical factor equal in rank to causality as a principle of explanation".¹ It is a principle that Jung proposes, not a finding.

Jung's scarab and his fish

The most quoted case is this one. A patient, at a critical moment of the treatment, tells Jung a dream in which she is given a golden scarab. While she is telling it, Jung hears a tapping at the window, opens it and catches an insect: a scarabaeid beetle, the common rose-chafer, the closest thing to a golden scarab found in those latitudes. According to Jung, the dream had been enough to loosen the patient's rationalistic attitude a little, and the beetle's arrival broke it for good; the scarab is also, he notes, a symbol of rebirth in ancient Egypt.¹

Two things to keep in view. First: this is a case told by Jung, with no name and no date, and there is nothing but Jung's word to check it against. Second: Jung himself warns that, with educated people, "cryptomnesia often cannot be ruled out with certainty" (in this case he says the patient did not know the symbol).¹

Another case he noted down with a date. On April 1, 1949 there was fish for lunch and someone mentioned the custom of the "April fish"; that morning Jung had noted an inscription about a fish (piscis); in the afternoon a former patient showed him pictures of fish and in the evening he was shown an embroidery with fish-like sea monsters; on the morning of the 2nd another patient told him a dream about a large fish swimming towards her. Jung was at the time studying the fish symbol in history; he writes that "only one of the persons mentioned here knew anything about it". He admits that the run made a considerable impression on him and had "a certain numinous quality".¹

Are repeated numbers (111, 333, 1212) synchronicity?

It is what people search for most, and the text's answer is short. In Jung's essay, the only case with numbers is this: the tram ticket bears the same number as the theatre ticket bought right afterwards, and that evening a telephone call mentions the number again. Jung writes that between them "a causal connection seems to me improbable in the extreme".¹ That is all: he attaches no message or meaning to the digits. In the copy I read I find nothing about "angel numbers" or about seeing the time 11:11; the word "angel" only appears in historical quotations.

The study of number series had been done earlier by Kammerer. For some fifteen years, he says, he had been taking notes on “series” in his notebooks, which he defines as a succession or simultaneity of equal or similar events "apparently without a common cause that keeps acting".² Some of his notes: on June 25, 1912 he sat in row 18 at a concert in Vienna and the next day, in another hall, in row 18 again; a brother-in-law of his had at a concert seat 9 and cloakroom number 9, and the next day seat 21 and cloakroom 21; and on September 2, 1906 his two restaurant bills, for quite different dishes, both added up to 1 Krone and 69 Heller, and he kept the two receipts as proof.²

Jung, who cites Kammerer, did not accept his explanation. He says Kammerer's material "contains nothing but runs of chance whose only “law” is probability", and that "unfortunately he did not attempt a quantitative evaluation of seriality".¹ Kammerer's book does have a chapter on "mathematical foundations", which I only read in part: in what I read, he holds that runs of the same thing should be more frequent than mathematical probability gives, and I did not see a calculation on his own cases.²

Is it a law?

No. The one who spoke of a law was Kammerer: Das Gesetz der Serie, "the law of series", which he explained through inertia, imitation and attraction.² Jung proposes a principle, and "law of synchronicity" does not appear in his essay.¹ Nor is it the "law of attraction", which assumes a cause (what you think attracts what happens to you); synchronicity, as Jung defines it, has no common cause, and in what I read he does not say it can be provoked or that anyone sends it.

Can it be tested? The horoscope experiment

Jung tried, and his account is the most honest thing in the book. With the collaboration of Liliane Frey-Rohn he gathered birth data of married couples, worked out their horoscopes and counted, among some fifty characteristics, how many couples had each one. Astrological tradition points to three constellations for marriage: the conjunction of Moon and Sun, of Moon with Moon, and of Moon with the ascendant, and Jung announces that he will investigate those three.¹

The first batch, of 180 couples, gave its maximum at Moon with Sun: 18 couples, 10.0%. A second batch, of 220, moved it to Moon with Moon (24 couples, 10.9%) and left the first at 4.5%. In a third, of 83, the maxima belonged to other aspects. Jung writes: "which only proves how fortuitous our “favourable” initial results were".¹ And among couples who were not married, the maximum dropped from 7.3% with 300 couples to 5.3% with 32,220: the larger the sample, the less "the best" stands out among fifty. Here are his numbers:

Jung tells it without adornment. A calculation by Professor Markus Fierz first gave a probability of 1 in 10,000 for his results, and on checking it came out as 1 in 1,500; Jung concludes that there is "little justification for regarding the immediate results of our statistics as anything more than chance". He admits that with large samples "the differences between the frequency values for the marriage aspects of married and unmarried persons disappear altogether", that "the result becomes blurred with larger figures", and that the calculation errors he found "all tend to exaggerate the results in a way favourable to astrology".¹ And then he writes the sentence that matters: "nothing but a chance result from the statistical point of view", and at the same time "It is just what I call a synchronistic phenomenon",¹ because it has meaning: it looked as if it validated the astrological expectation.

That is the key to his idea, and the reason it is hard to put to the test (my reading; Wikipedia records the objection from science that it is neither testable nor falsifiable).³ If what makes an event synchronistic is the sense found in it by whoever lives it, no probability calculation can say it is not, because Jung already concedes that, statistically, it is chance. I could not check Fierz's calculation or the original data.

And statistics?

Persi Diaconis and Frederick Mosteller, statisticians, studied coincidences in a 1989 paper. According to their abstract, once coincidences with an apparent cause are set aside, four principles account for large numbers of the remaining ones: hidden cause; psychology (memory and perception); multiplicity of endpoints (counting "close" or nearly alike events as if they were identical); and the law of truly large numbers, which says that when enormous numbers of events and people and their interactions cumulate over time, "almost any outrageous event is bound to occur". And they conclude: "These sources account for much of the force of synchronicity."⁴ I only read the abstract.

The "Your year of coincidences" tab does that calculation. If every day you have 100 chances to notice two equal things (two numbers, two names, two times) and each has a 1 in 10,000 probability, you expect about 3.65 coincidences a year, and the probability that none comes your way is under 3%. What the calculation does not give is how many chances you have and what looks equal enough: whoever is looking decides. Jung says it in his own way, in a footnote: "The numinosity of a series of chance happenings grows in proportion to the number of its terms."¹ The feeling grows with the count.

And quantum physics?

In the text I read, physics enters through Wolfgang Pauli: Jung says Pauli suggested replacing, in his scheme, the opposition of space and time with "(conservation of) energy" and the "space-time continuum", and that "We finally agreed on the following quaternio", with two pairs: indestructible energy against the space-time continuum, and constant connection through effect (causality) against inconstant connection through contingency, equivalence or "meaning" (synchronicity).¹ Pauli's essay that accompanies Jung's in the same volume is about archetypal ideas in Kepler's work, not about quantum mechanics. I find no quantum entanglement in the text; according to Wikipedia, a physicist, T. Filk, considers it a plausible model of what Pauli had in mind, and that I did not read.³

When coincidences weigh

A note, because this is a subject that sometimes hurts. Seeing meaningful coincidences is a common experience and almost always harmless. But if someone feels that coincidences are messages aimed at them that others cannot see, that they multiply until they cannot sleep, or that they say what they must do, it is worth talking it over with a mental health professional. Wikipedia records that an overabundance of meaningful coincidences can occur in a psychotic delusion.³ This article does not replace anyone who can help; findahelpline.com leads to a helpline in each country.

What I could not read

I read the 1955 English edition of Jung's essay (The Interpretation of Nature and the Psyche, Pantheon/Bollingen), "revised by the author" according to its editorial note: the foreword, the exposition (the definition, Kammerer, the scarab, the fish), the horoscope experiment from its start to the end of its tables, and the scheme with Pauli. I did not read the German original of 1952, the Pauli–Jung correspondence, the "forerunners" (Leibniz, Schopenhauer) or the conclusion. Of Kammerer I read the introduction, the first notes of his collection and part of the probability chapter; the book has some 450 pages. Of Diaconis and Mosteller, only the abstract. The origin in the I Ching, the 1930 address, Pauli and quantum physics I take from Wikipedia. I did not check Fierz's calculation and I cannot verify the scarab case.

What we do with this

Anima Mundis brings together 3, 5 or 7 strangers who chose the same frequency at the same hour. That two people coincide there is not synchronicity: it has a cause, the matching, and it is in the code. It is Diaconis and Mosteller's "hidden cause", but in plain sight. What the Observatory counts is the voices that arrived and at what UTC hour, and nothing else. Real coincidences can be measured. With the others it is worth remembering Kammerer and Jung: before asking what they mean, count how many chances there were.