柏拉圖在《法律》對喜劇表演的示警，表達出柏拉圖為什麼不喜歡大多數人以為的「幽默」。他批評喜劇模仿再現了「醜的身體與思想」，並透過「無知」影響我們。本文將從《法律》第七卷裡對喜劇模仿的示警展開，試著釐清柏拉圖對於「笑」主要憂慮的是什麼，「笑」和「無知」又有什麼關聯。本文試圖論述柏拉圖批評的只是具攻擊性的「笑」，此外，他對幽默的運用也不能以當代美學家所謂「笑」的優越論來概括。文中將聚焦於「笑」與「無知」的關聯，從《饗宴》、《泰鄂提得斯》、《尤悉弗若》、《大希比亞斯》、《高吉亞斯》、《理想國》等對話錄裡柏拉圖自己運用幽默的橋段，來了解柏拉圖如何運用幽默護衛他自己的知識立場，又如何形成友好良善的轉變契機，進一步促使人們去挑戰改變現有的知識狀態，從無知，邁向知識。

Plato’s sense of humour must be very different from that of most Athenians. In Book VII of the Laws, Plato delivers his criticisms against comic imitations. For comic imitations represent “ugly bodies and thoughts” and “influence us to do and say laughable things through ignorance.” The paper starts with this passage and tries to clarify what Plato worries about laughter and its link to ignorance. By analysing the plots where Plato employs humour and laughter in his dialogues, I will argue that Plato only criticises the laughter coming out of malice. Besides, his use of humour cannot be simplified to the Superiority Theory of Humour, as called by contemporary aestheticians. In the plots of Symposium, Theaetetus, Euthyphro, Hippias major, Gorgias and Republic, we may see how Plato uses humour to defend his position on the epistemic battlefield, how he cautiously makes a great effort to turn hostility into friendship, which is crucial if his use of humour is to urge people to challenge the conventional views, step out of ignorance, and approach the true knowledge which the philosopher likes to share.