Definition
Verification is the act of checking a claim against reliable evidence or a primary source before accepting it as true. It is the practical step that turns skepticism from an attitude into an outcome: instead of merely doubting a claim, the verifier goes and finds out.
The key distinction is between a primary source — the original document, dataset, or first-hand account — and the chain of retellings that usually carries a claim to us. Most false beliefs survive precisely because no one in that chain ever goes back to the source. Verification breaks the chain by returning to the origin.
Why it matters
How it works
To verify a claim, you trace it upstream. A statistic cited in an article should lead to a study; a study should lead to its data and methods. A historical anecdote should lead to a contemporary record rather than a later popular retelling. At each step the question is the same: is this the source, or just another repeater?
Verification carries a real cost in time and access, and that cost explains the pattern The Book of Common Fallacies documents repeatedly — the claims everyone repeats are often the ones no one has checked, because checking is harder than retelling.