What is the strongest argument for Plato's ideal state?I need to write an paper and I didn't really get this part.

To get a better answer, it would be good if you could tell us
which aspect of the ideal state you want addressed.  The part I have the strongest feelings about
is the idea that the ideal state would be ruled by a philosopher
king.

I really wish that this were possible.  The argument in favor
of this is that a philosopher king would just do what is best for the society without having to
worry about what is popular.  We could really use this today at a time when our elected leaders
will not do the things that are needed because they are afraid they will not get reelected if
they do those things (like cutting back on Medicare and Social Security in some
way).

Sadly, there is no way to be sure that we are going to get a
good philosopher king instead of a tyrant.