Definitions

20 pages on this site touch on this topic.

• A taxonomy of coincidences — Eleven descriptive lenses for sorting coincidence stories — not rigid categories, but a way to ask the right analytical question for each kind of claim.
• Apophenia — The tendency to perceive meaningful connections between unconnected things — coined clinically, now mostly used for a mild, everyday tendency.
• Base rate — How common something is in a relevant population or time period, before taking the specific case in front of you into account at all.
• Causation — One event bringing about, or contributing to, another — a claim needing its own evidence, not established merely by two events co-occurring.
• Chance — An outcome's dependence on factors not accounted for by the model being used to describe it — not the absence of any cause at all.
• Clustering illusion — The tendency to see meaningful streaks or clusters in sequences that are actually random, because random sequences cluster more than intuition expects.
• Coincidence — The notable co-occurrence or close succession of events for which no relevant causal connection is known or established.
• Confirmation bias — The tendency to notice, seek, and remember evidence that fits what you already believe, while giving less attention to evidence that doesn't.
• Correlation — A statistical tendency for two things to vary together, which can arise from direct cause, shared cause, chance, or how the data was collected.
• Fate — The idea that events are predetermined toward an outcome — culturally and historically significant, but not a scientific finding.
• Hindsight bias — Overestimating how predictable an outcome was, and misremembering your own earlier uncertainty as smaller, once you know how it turned out.
• Independence — Two events are independent when the occurrence of one doesn't change the probability of the other — an assumption that is easy to state and easy to get wrong.
• Luck — A way of describing a favorable or unfavorable chance outcome after the fact — a useful everyday word, not a measurable force or property a person can possess.
• Pareidolia — Seeing a specific, familiar pattern — most often a face — in something that doesn't actually contain one, such as a face in a cloud or a piece of toast.
• Quick guide: coincidences in ten minutes — A fast, scannable overview of this site's core ideas, each linked to the fuller explainer, for a reader who wants the shape of the argument before the depth.
• Randomness — A process whose individual outcomes aren't predictable in advance, even though its long-run pattern of outcomes can be described precisely.
• Serendipity — A chance observation or accident that leads, through a real subsequent chain of insight and effort, to a valuable discovery.
• Synchronicity — Carl Jung's term for a meaningful coincidence between an inner state and an outer event, proposed as connected by meaning rather than cause.
• What is a coincidence? — A working definition that separates the event itself from the surprise, the improbability, the meaning, and the causal claim people often bundle together.
• Why coincidences feel profound — Surprise, causal narrative, and vivid memory combine to make a chance event feel significant, weaving together mechanisms covered separately.