Refers to what is reasonable, logical, or morally right; often used in phrases like 道理で (no wonder) or 道理にかなう (to be reasonable).
What he says is reasonable.
道理で彼が怒るわけだ。
No wonder he's angry.
The teacher explained the moral reasoning to the children.
He is a person who understands right from wrong.
It stands to reason that effort leads to success.
道理 is a formal word for logical reasoning or what is right, while 筋 in this sense usually appears in set phrases like 筋が通る about whether something makes sense.
perfectly reasonable; standing to reason