事わけ

(1)a rational motive for a belief or action; "the reason that war was declared"; "the grounds for their declaration"

(2)信念または行動の合理的な動機

(3)an explanation of the cause of some phenomenon; "the reason a steady state was never reached was that the back pressure built up too slowly"

(4)ある現象の原因の説明

(1)