Here are five post-existentialist philosophies and what is wrong with each:
1. Structuralism - An anti-existentialist philosophy that attempts to return to the search for the absolute. Well intentioned, its flaw is attempting to return language as the basis of truth without considering meaning.
2. Post-Structuralism - Jumping on the obvious flaw of Structuralism, this attempted to show the absence of absolute truth from the vagueness of language. In part, this philosophy is also flawed from its ignorance of meaning. One could claim that words have no meaning, because words are made of letters, and letters are meaningless. This is worthless reductionism at its worst.
3. Feminism - Note: In attacking Feminism I am not attacking the fight for equality for women! I am simply attacking the idiotic fundamental argument: All philosophy is flawed because it came from men who defined truth using gender biased language. Again, language is not the source of philosophy, and if the only argument you can give against a philosophy is that it came from a man, you are basing your whole belief on one of the oldest logical fallacies. (but, they would argue, logical fallacies were created by men).
4. Anti-Rationalism - The belief that the world is flawed, therefore it is the philosophy of the world that is flawed. This is what happens when you take the Feminist argument to its logical conclusion. This philosophy presupposes that the world is in an environmental and political mess, and that it is "rational" philosophy that got us here. My question is how is the world worse off today than it was in the pre-enlightenment times? Reason is not the cause of environmental and political problems, it is the cure.
5. Post-Modernism - Like Existentialism, Post-Modernism is as easy to define as the shape of a cloud. Any one can say what they want and call themselves a post-modernist. Still there are faulty ideas that are widely popular. The worst is complete toleration of plurality. Toleration of others ideas and actions is an Aristotelian virtue. It sits between two vices. Intolerance of all points of view except your own is definitely a vice. Complete toleration and acceptance to all views is also a vice, just as destructive as intolerance. The latter is a vice shared by most post-modern thinkers. Why is it a vice? Because recent history has proven that ideas such as "multiculturalism" ultimately prove to be "no culturalism". People that are open to all ideas, are in reality not open to any ideas at all. The happy medium, I believe, is a combination of democratic toleration of other opinions and rational skepticism to weed the unhealthy opinions out. People have the right to express their opinions, and I have a right not to believe them. That is what I call post-post-modernism.