What assumption is flawful when suggesting two powerful countries together could dominate globally?

The assumption in the argument that two powerful countries together could dominate globally is flawed due to the composition fallacy. This fallacy occurs when one incorrectly assumes that what is true for individual members of a group will also be true for the group as a whole. In this context, while each of the two countries may be powerful on their own, this does not guarantee that their combined efforts would lead to global dominance. Factors such as differing political agendas, economic systems, or cultural influences could affect their ability to work together effectively, leading to a situation where their combined strength does not equal a significant advantage on the global stage.

The other choices involve different types of reasoning errors. Selected instances focus on drawing conclusions from a small number of examples rather than a comprehensive analysis. Hasty generalization tends to make broad claims based on insufficient evidence, and post hoc reasoning incorrectly assumes a cause-effect relationship based on the order of events. While all these errors have their own contexts, the composition fallacy specifically highlights the oversight of assuming that the characteristics of individual powerful countries necessarily translate to success when combined.