A Jungian term for a connecting principle that he thought would give meaning to a series of causal coincidences, as for example the frequent recurrence of a particular number over a short span of time. Carl Gustav Jung thought that these coincidences were meaningful and would not accept that they could happen in accordance with the normal laws of probability that is, by pure chance and that in a very much larger series of observations, these anomalous clusterings would disappear. Instead, he put forward a metaphysical notion where all events of temporal coincidence, like Deja VU and the act of precognition, had spiritual significance within a purposeful universe. Therefore, he thought, their meaning should be sought in their structural relationship as well as in their causal antecedents within the meaningful superstructure. Jung’s structuralism entails a form of experiential harmony, a harmony among events, and a harmony between the structure of our understanding and the event structure. He believed that his new notion of synchronicity supplemented the classical and medieval principle of correspondence, which, he said, had existed rather naively and unreflectingly up to the time of Leibniz and then had been superseded by scientific thinking.
Since Jung, there have been many studies done on coincidence from a psychological point of view, notably those recently by Ruma Falk and her collaborators. The findings seem very clear and not surprising. First, more of us are impressed when coincidences happen to ourselves than when they happen to others. Second, the rate at which coincidences are experienced varies very much from person to person: Some connect occurrences that are only vaguely alike, and thus overestimation occurs; others see very few connections. Third, reactions to coincidence stories depend on how the story is told; if told in a matter-of-fact way, it is not taken so seriously as when the story is elaborated upon, giving emphasis to details.