The author doesn’t discuss weaknesses of both types of systems. She discusses a multipolar system that created instability, but she also discusses a bipolar system that promoted peace. Also, the function of this paragraph is to reinforce her argument from P3.

In P3, the author suggests that the current multipolar system in Europe might threaten security in the future. But in P4, she discusses a multipolar system in Europe that created instability in the past. She does this to reinforce her argument that the traditional view of multipolar and bipolar systems should be reassessed.

The author does give an example of a bipolar system that promoted peace, but she never argues that Europe should embrace a new bipolar system. Her overall argument isn’t about European stability; it’s about the traditional view of multipolar and bipolar systems. The European multipolar system in P4 is just an example to reinforce her main point.

In the final paragraph, the author gives an example of a multipolar system in twentieth-century Europe that created instability and conflict. The purpose of this is to expand on the argument in P3 that the traditional view of multipolar and bipolar systems should be reassessed.

In the final paragraph, the author gives an example of a bipolar system that promoted peace, but she doesn’t review the characteristics of both members of this particular system. Even if she did, the function of the paragraph is to reinforce her argument that the traditional view of multipolar and bipolar systems should be reassessed.