Reason, logic, or sense; the principle or fairness behind something — what makes sense or is right.
彼が遅刻したには道理がある。
There is a reason for his being late.
道理にかなった判断を下すべきだ。
You should make a decision that makes sense (is reasonable).
その批判には道理があると思う。
I think there's truth to that criticism.