One fatal flaw of libs is their inability to see evil when it appears. In lib minds all groups, violent or non-violent, can be reasoned with. You just have to show the right amount of compassion...and willingness to appease. The delicious irony is that Islamo-fascists would just as eagerly cut the throats of all the Bush/conservative-hating lefties on DUmmyU and other lib sites as they would any non-Muslim.
It's hard to see something you don't believe in to begin with. Evil is essentially a development from monotheistic religions; primarily Judaism and Christianity. Philosophy, in comparison, mostly downplays (if not disputes) its existence.
Liberalism is as much a religion unto itself as it is a political belief. Evil as a concept plays very little part in its belief system.
Actually, libs recognize evil. They also think themselves so intelectually advanced (evolution, donchyaknow) that "evil" is subject to (their) superior reasoning.
To libs, evil can be convinced to become good.