challenge an assumption

Translations
оспаривать предположение
He decided to challenge the assumption that the project was impossible.
Он решил оспаривать предположение, что проект был невозможен.
Definitions
To question or dispute a belief or idea that is taken for granted, often in order to explore its validity or to encourage critical thinking.
Words
assumption

noun
предположение
challenge

verb
бросать вызов