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Expected to act with good judgment or common sense.
You should know better than to leave your keys in the car.
It is reasonable to expect you to understand the risks of such carelessness.
She should know better at her age—she can’t keep eating junk food every day.
She is old enough to understand the consequences of her unhealthy habits.
Often used to express disappointment or criticism when someone fails to act sensibly despite having the knowledge or experience to do so.
Use 'you should know better' only when the person has clear knowledge or experience that should prevent their action. Avoid using it for actions outside their control or knowledge.
This phrase implies prior knowledge or experience. Do not use it if the person could not reasonably be expected to know better.
The phrase combines the modal verb 'should' (indicating obligation or expectation) with 'know better' (implying superior judgment or experience). The expression has been in use since at least the early 19th century, evolving from earlier forms like 'to know better than' in the 17th century.
This phrase is typically used in informal contexts to gently or firmly criticize someone's poor judgment. It assumes the person has prior knowledge or experience that should guide their actions. The tone can range from concerned (e.g., parental advice) to exasperated (e.g., reprimanding a friend).