1) Liberals believe they can change human nature. Sure, human beings can be shaped and molded to a certain extent. Any parent who has spanked a child can tell you that. However, most people care more about what they're having for lunch today than an earthquake that kills ten thousand people on the other side of the world. We're just built that way and no amount of sensitivity training, preschool classes, or Michael Moore documentaries is going to "fix" it.
2) Liberals believe we can talk everything out with our enemies. One of the weirder quirks of liberalism is their belief that many of our bitterest enemies have rational reasons for disliking us and that can easily be talked away if they realize we're good people. Hence, the common liberal refrain of, "Why do they hate us?" The reason this is a particularly odd belief is that liberals don't even believe this about conservatives in the United States. The average liberal thinks that if we're nice enough, we can reach an understanding with Hugo Chavez or Mahmoud Ahmadinejad, but Rush Limbaugh and Glenn Beck can't be reasoned with.
3) Liberals don't have enough respect for our culture and traditions: To liberals, our cultural, economic, and political norms were formed by backwards troglodytes making arbitrary decisions based on superstition and racism. Unfortunately for them, as a general rule, that's not so and proceeding as if it is, will often lead to exactly the same difficulties that our ancestors already dealt with in times past. No matter how smart we are, as Thomas Sowell would say, our wisdom is often no match for the "distilled experience of millions who faced similar human vicissitudes before." Truly wise people are aware that there is a great deal that they do not know.