Butterfield's 1931 text warns that the whig historian forgets a line of descent is his own 'mental trick' and takes it for a line of causation

whig-historycausationbutterfieldhistoriographylineage

In the same passage as the "root"/"anticipation" warning (claim-butterfield-1931-text-names-root-or-anticipation-found-by-resemblance-as-misleading-analogy), Butterfield writes: "Working upon the same system the whig historian can draw lines through certain events, some such line as that which leads through Martin Luther and a long succession of whigs to modern liberty; and if he is not careful he begins to forget that this line is merely a mental trick of his; he comes to imagine that it represents something like a line of causation."

On this wording the fallacy's payload is the slide from a resemblance-line, drawn by the historian, to a causal line asserted of the past. Resemblance-seeking as such is not the harm. That yields a testable criterion for any "lineage" or "precursor" claim: does the text assert or imply causation or influence, or does it only place two positions in sequence?

The vault has applied the test implicitly in its Brooks–Dreyfus cluster (claim-brooks-dreyfus-lineage-is-convergence-not-citation); this note supplies the source wording for it. Application to one instance: observation-jordanous-precursor-framing-performs-butterfields-likeness-step-but-not-his-causal-step.