Cogent
Etymology
From Latin "cōgēns," the present participle of "cōgere" ("to drive together, to compel"), from "co-" ("together") and "agere" ("to drive"). The buried image is of a case so tight it herds you toward its conclusion. English adopted it in the 17th century for arguments that carry exactly that compelling force.
adjective · /KOH-junt/
Clear, logical, and convincing.
What it names
Reserve it for reasoning that all but forces your agreement — a cogent argument compels by its logic, not by charm or volume.
Example
He made a cogent case for delaying the launch, and the room, reluctantly, agreed.
Related idea
Not the same as tenable: a tenable position can merely be defended without collapse, while a cogent one actively drives you to accept it.