: A small-scale display of the Wall Titans' power to deter world invasion.
: 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 10 : A Sound Argument
If you are referring to the episode " A Sound Argument " (Season 4, Episode 10), it is a story centered on the heavy burden of duty and the erosion of hope. : A small-scale display of the Wall Titans'
The "sound argument" of the title refers to the cold logic that sacrificing one individual (Historia) is a necessary evil to save the nation. 10 : A Sound Argument