自相矛盾

很久以前，楚国有一个人到集市上卖矛和盾。他举起一面盾，大声喊道：“看看我的盾！它坚固得不得了，世界上没有任何东西能把它刺穿！”大家都停下来听。接着，他又拿起一支矛。“再看看我的矛！它锋利得不得了，世界上没有任何东西是它刺不穿的！”听起来也很厉害。可是，人群中有个人看看矛，又看看盾，问道：“那如果用你这支矛，去刺你这面盾，会怎么样呢？”卖东西的人一下子愣住了。如果矛刺穿了盾，那么盾就没有他说的那么坚固。可如果盾挡住了矛，那么矛也不是什么都能刺穿。他答不上来了。这就是“自相矛盾”这个成语的来历。“矛”是古代用来刺击的兵器，“盾”是用来抵挡攻击的防具。今天，我们说一个人“自相矛盾”，就是指他说的话、想法或者做的事情前后冲突，不能同时成立。矛和盾早已离我们很远了，可那个问题今天仍然很好用：这两件事，真的能同时成立吗？

Long ago, a man in the state of Chu went to market to sell spears and shields. He lifted one of his shields and called out, “Look at this shield! It is so strong that nothing in the world can pierce it.” People stopped to listen. Then he picked up a spear. “And look at this spear! It is so sharp that there is nothing in the world it cannot pierce.” That sounded impressive too. But someone in the crowd looked at the spear, then at the shield. “What would happen,” he asked, “if you used that spear to pierce that shield?” The seller froze. If the spear pierced the shield, then the shield was not as strong as he had claimed. But if the shield stopped the spear, then the spear could not pierce everything. He had no answer. This old story gave us the expression zì xiāng máo dùn. Máo means “spear,” and dùn means “shield.” Today, the expression is used when two things someone says or does cannot both be true. The spear and shield are gone, but the question is still useful: Can both things really be true?