1.
shallow, superficial, thoughtless, foolish
Lacking depth of thought or consideration. Describes ideas, plans, or behavior that are poorly thought out or naively simplistic.
浅はかな考えだった。
It was a shallow way of thinking.
Usage
A fairly strong negative evaluation, often used to criticize decisions or thinking that lacks foresight or depth. Can be used about one's own past actions in a self-critical way. The word carries a literary or somewhat formal tone.
The kanji form 浅はか uses 浅 (shallow), reinforcing the metaphor of insufficient depth.