这是一个困扰思想家数个世纪的哲学问题。

This is a ___philosophical problem that has puzzled thinkers for centuries.

拉尔夫开始向皮吉征求意见，并问他哲学问题。

Ralph started taking advice from Piggy and asking him ___philosophical questions.

她的哲学著作探讨现实的本质。

Her ___philosophical writings explore the nature of reality.