What type of system exists today and how old is it?
If we assign a date or time-frame for the existence of a phenomenon, this will in itself affect what it is we say exists. For instance, if we claim that Europe existed 3000 years ago, we are probably not talking of culture or even politics but merely geography. Similarly, but with a reverse logic, if we believe that particular features of contemporary international relations (e.g. the speed and quantity of transnational communications and interactions, or capitalism and market economy) matter more than some other aspects (e.g. the formal division of the world in separate and sovereign states) this affects when we would say the current order began.
In the book International Systems in World History, Barry Buzan and Richard Little suggest that in order to periodise (separate in time) different international systems, one must pay attention to the type of unit that dominates. On this notion, they present their own periodization (see page 394 where they compare their suggestion with those of other scholars) of international systems. According to them, the latest primary turning point in world history, from an IR-perspective, is ca. 1500 AD.
You may of course believe that unit-change is important and still come up with other dates. Let us say that you believe that the development of the welfare state and industrial states or democracies, are of decisive importance and select the late 19th or early 20th century as the latest turning point. Perhaps the development of modern nationalism and ideological political movements make you pick 1789 and the French Revolution as the beginnings of the contemporary system.
Maybe the de-colonization process of the 1950s and 1960s marks the start. Perhaps it isn’t change of units that is of primary importance at all. A neorealist could, based on ideas of polarity, say that the latest turning point is the end of the Cold War when the system switched from a bi-polar to a uni- or multipolar structure. Others would mention globalization and post-industrial society, etc. Think through the following questions: What is, in your mind, the most important aspects of the contemporary international system, and how long has this order existed? Argue for your answer in theoretical terms, utilizing Buzan and Little’s toolbox. Prepare to discuss your answer at the first seminar.