Someone needs the line between a grievance and a mandate — between being wronged and being obligated to act.

The escalation from "right" to "duty" is the whole moral engine of the document. A right lets you act; a duty condemns you if you don't. And the trigger is carefully set: not a single abuse, not a bad law, but a "long train" of them "pursuing invariably the same object" — a pattern that proves design. One injury is an incident; a pattern is a plan. That distinction is what separates revolution from riot. The sentence also smuggles in the forward obligation: you don't just tear down, you "provide new guards," which is why the document ends by constituting new states rather than merely dissolving old ties.