The problem with the arguments for inaction isn't that they're wrong, it's that they prove too much.
They step around their arguments, like sea-weed on a Massachusetts beach.
One of the arguments for intervention arising from the Syria strikes relies on a bit of sophistry.
early 14c., "statements and reasoning in support of a proposition," from Old French arguement "reasoning, opinion; accusation, charge" (13c.), from Latin argumentum "evidence, ground, support, proof; a logical argument," from arguere "to argue" (see argue). Sense passed through "subject of contention" to "a quarrel," a sense formerly attached to argumentation.