: The episode highlights the growing instability of Eren, who has grown cold and detached, alarming his closest friends, Mikasa and Armin.
: In the present day, we see the tragic outcome. Historia is shown pregnant and despondent, seemingly having accepted a fate she never wanted. 10 : A Sound Argument
: To maintain the Founding Titan's power, Historia must inherit the Beast Titan and produce as many children as possible during her remaining 13 years. The Emotional Rift : The episode highlights the growing instability of
: Paradis must spend 50 years modernizing their military to compete with the world. who has grown cold and detached
The "sound argument" of the title refers to the cold logic that sacrificing one individual (Historia) is a necessary evil to save the nation.