Kelly Mears

Plausible Mechanism

A causal explanation that was inferred rather than tested, and reads as more rigorous for being specific.

Method2 min read210 words10 out · 17 in
also calledUnearned explanationBecause X

A plausible mechanism is an explanation of why something happens that was never verified — offered because an explanation is the natural shape of an answer, and a specific one sounds more authoritative than "I don't know".

The trap is structural rather than careless. Saying "the compiler requires this cast because the inferred type lacks the property" feels like rigour; saying "the compiler requires this and I have not established why" feels like weakness. But only the second is honest before the ten-second experiment — delete the cast, run the type checker — has been run.

Two things make the failure mode worse than it looks. First, unearned causal claims land mostly in explanatory artifacts: code comments, docblocks, review comments, change descriptions. Nothing executes against prose, so a wrong mechanism in a source file passes every gate and inherits the credibility of the gates it passed. Second, a merged change description becomes the permanent record — see Provenance.

The rule that survives: before writing "because X", run something that would tell you if X were false. If you cannot, write what you observed and say the cause is not established. When a reviewer asks why, that question is the trigger to go find out, not permission to guess more precisely.

See also7

Hand-picked in the note itself — the neighbours worth reading next.

Related2

Nearby in the graph rather than deliberately chosen. Looser, sometimes surprising.

Linked from17

Notes elsewhere in the wiki that reach for this one.