Time-bounded Arguments

What is time-bounded argument? Its the kind of argument that are closely linked to a certain period of time. Many use time-bounded arguments to demonstrate their point are justified by the history. But if you can prove a negative and a positive both in history, doesn't that discredit history as a reliable justification.? Think about it. If you can prove that Islam create and provoke violence using history of the past decade egregious terrorism that has been sprouting out of the Middle East  under the name of Islam, but, meanwhile your opponent respond with quoting the heyday of Islamic civilization during Ottoman empire, doesn't that make history not a good justification ? That's the problem, certain arguments cannot be supported by history because history prove both contrasting notion valid, ergo its either it is a truthful paradox or it proves history itself incapable to be used as justification. Hence how do you prove Islam is a religion of peace or  a religion that invoke violence, if not with history? Im not saying that history cannot be cite as justification, but first the notion must be constant throughout history to provide a convincing prove, if not, in this case, history will only be a weak argument. So to prove a notion that are inconsistent through the layout of history, we must resort to the doctrine of the religion itself and its honest interpretation and judged by our moral standard. If I'm wrong and had deluded my own rationale, please help me clear it up.