The four children appear in the Talmud Yerushalmi, where Rev Chyyia is quoted as bringing this parable. The text says that the Torah speaks of four children -- it uses the word " k'neged"  which has a wiggly definition but one of the meanings would be "in opposition to" or "against." So, Reb' Chyyia is saying that the Torah is speaking "against" these four kinds of children -- including the wise child, who we often valorize, but perhaps the Rabbis did not?

In fact, the Torah doesn't classify four children -- the Rabbis made up the children to make a story of the four times in the Torah when we are told to relate the story of the Exodus to our children. So, the Rabbis made up the wise/wicked/simple/too-dumb-to-ask children based on the mandates "tell your children," creating hostility and insufficiency on the part of the children. Even going so far as to tell the wicked child that they wouldn't have been liberated with the rest of us. 

While it is certainly an impulse of humanity to classify others, this year let us encourage those around us to define themselves in more expansive ways.  

haggadah Section: -- Four Children
Source: Ariel Kates