know better

Idioms  

1. Be able to recognize something as wrong or not possible, as in Mary should know better than to leave her child alone in the house, or Try to get in without a ticket? You know better than that. [c. 1700]

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Example Sentences

In talking with them, I realize that a true friend would know better than to act the way I did and for that I need to be a better friend.

From Los Angeles Times

But when I apologized by admitting it was my first real investment and I simply didn’t know better, the tension defused.

From The Wall Street Journal

“Edda, if I didn’t know better, I’d almost wager that you didn’t expect your mother and me to be home.”

From Literature

I know better than to attempt to get Celia to reveal anything before she’s ready, so I make myself a peanut butter and jelly sandwich and let Celia’s little mystery go, for now.

From Literature

And presuming you know better in Washington.

From Slate