Butterfly Logic
Cum Hoc Ergo Propter Hoc · Confusing Correlation and Causation · Third Cause · False Cause
The notion that a connection implies causality, with one earlier event being the cause of a subsequent event.
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Origin
The fallacy cum hoc ergo propter hoc (Latin: "with this, therefore because of this") has roots in ancient Greek philosophy, with warnings from Aristotle and Sextus Empiricus against assuming causation from correlation. The phrase describes the error of deducing cause-and-effect solely from observed association. Unlike post hoc ergo propter hoc (which involves temporal sequence), cum hoc addresses simultaneous or unordered events. The specific term "Butterfly Logic" for this fallacy appears less documented in scholarly literature.
Updated February 22, 2026