Glossary
Plain-language definitions of the terms used across the site — chance, randomness, independence, causation, correlation, synchronicity, and more — each linked back to where they matter.
- 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.
- 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.
- 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.
- 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.
- 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.
- causation
- One event bringing about, or contributing to, another — a claim needing its own evidence, not established merely by two events co-occurring.
- 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.
- 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.
- 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.