Forms are put to their most significant use in Plato's final argument for the Immortality of the Soul, where they are presented as teleological causes. The best reason why anything in the sensible world is the way it is will always be given through an appeal to the Forms it participates in. The Theory of Forms is the hypothesis from which all of Plato's arguments follow, and itself is taken for granted. Thus, Forms serve as the ground for everything Plato says, and must then necessarily imply the Theory of Recollection and the Immortality of the Soul. In spite of all this, it is very difficult to determine precisely what we should say about Forms. (This dialogue's Analysis sections provide hints toward several different possible answers).

Popular pages: Phaedo