paradox

It is a curious paradox that some people are lonelier when they are in a crowd.

(Chinese) 一个奇怪的悖论是，有些人在人群中反而感到更孤独。

The 'liar paradox' is a famous example used in philosophy and logic classes.

(Chinese) “说谎者悖论”是哲学和逻辑课上使用的一个著名例子。