Do you mean JFK? If so then he believed that science could evolve to the point that it can regrow limbs.
A question like this cannot be answered simply. However, in short, apart from communism, all other ideas of Nationalism, Democracy and Feminism have achieved some degree of success in the 20th Century.
After World War I and especially World War II, we saw a surge in nationalism among colonial possessions all over the world. Most of these countries became democratic republics but many also saw dictatorships and kingship.
Universal suffrage and feminism also took a hold after World War II where women were given more social freedoms and the movement is still continuing to this day.
