The overall theme of the book – that Great Powers are neither wholly free nor entirely driven by circumstance, but rather, are capable, at least in part, of shaping the international environment that will subsequently compel them to act – leads us naturally to wonder how much states are capable of foreseeing the outcomes of their own actions. Put another way, having examined the model and evaluated it empirically, it is worth asking, by way of conclusion, whether the light that it sheds on the past can tell us anything valuable about the present or, more tentatively, about the future.

In this concluding chapter I focus in a somewhat unorthodox manner on the question of what we can and cannot learn about the future based on the model. I start out with a discussion of some of the issues facing the United States and the international system in the 21st century. I discuss the model's implications for likely long-term systemic outcomes, and then I look at the direct impact of changing just a single parameter of the model in a manner that corresponds with some interesting qualitative change in the world. Next, I examine the indirect impact of changing one parameter of the model on the rest of the system. What this discussion demonstrates is the fact that, given the interconnectedness of systems, that change reverberates through every other aspect of the system. When we understand both the wide-ranging implications of a change in just one part of the system and the fact that the rest of the system will rarely remain constant for long, we start to comprehend the difficulties facing any systemic forecast.