All Monks at level 3 must subscribe to a fighting philosophy. You have advanced far enough that you must make a choice – whether to follow the Path of Harmonious Balance and seek to be at peace with the world, or to follow the Path of Inevitable Dominion and seek to dominate the world.
To summarize, the Path of Harmonious Balance emphasizes support of a party through spell-like abilities (using ki), healing, while keeping a concentration on fighting styles. The Path of Inevitable Dominion emphasizes attacks that use ki to debuff, curse or destroy enemies outright.
You may only choose one path. All monks must choose a philosophy feat.
Monk philosophy paths differ from the Character creation paths any player may take when first creating a player character.