Card 18 of 24 · Relevance
Fallacia originis
Judging the river by its source instead of its water.
An idea should be evaluated on its merits, not merely where it came from.
Example
“That proposal came from a tourist, so it can’t be worthwhile.”
Argumentum ad originem: judging a claim by its genesis or source. Ad hominem is a special case aimed at persons.
Diagnosis: A belief’s origin may affect how much initial trust we give it, but its truth depends on present evidence. Confusing the context of discovery with the context of justification breaks the link.
“Freud explained religion as wish-fulfillment, so it’s false.” Even if religious belief has psychological roots, that doesn’t settle whether God exists — as Freud himself acknowledged.
“Christmas has roots in pagan festivals, so celebrating Christ’s birth is pagan.” The meaning of a practice is not fixed by its calendar origin.
“That ethical theory came from a secular philosopher, so Christians can’t use it.” Augustine and Aquinas freely drew on Plato and Aristotle.
Trail recovery
Grant that origins can be interesting and sometimes relevant to reliability, then ask what the evidence says now. Charitably, the speaker may be raising a valid source-criticism concern.
Try saying: “Where it came from is worth noting — but does the idea hold up on its own?”
Keep questioning. Keep exploring.