Abstract:An American Tragedy, based on a real case, is a naturalistic novel written by Theodore Dreiser, whose works have broken with the optimistic tradition of earlier American realism. He vividly depicts the short and tragic life of Clyde Griffith ---- a poor American young man who degenerates from an innocent teenager into a merciless murderer and is finally put into death. The story reveals that the then moral outlooks in America corrupt the minds of Americans and criticizes the falseness and corruption of American political and legal systems. 

　　　This paper aims to analyze the basic causes of Clyde’s tragedy, and discuss Dreiser’s naturalistic style. There are three main factors leading to Clyde’s tragedy, which are respectively individual factors, social factors and family factors. First, his low-quality natures make him easily influenced by the surroundings. Then, the social factors consist of three parts ---- the economic cause, the cultural cause and the political cause, which should be most responsible for his corruption. What’s more, his family also affects him to a great extent. He is eager to change his life due to his poor family condition and his parents’ attitudes toward poverty. From the analyses a conclusion can be reached about how the internal and external causes affect people's fate，in order to enlighten others to set up correct outlooks on life.

Key words: causes; individual; social; family; naturalism

摘要:《美国的悲剧》是西奥多•德莱赛基于一个真实事件的自然主义小说。他的作品打破了早期美国现实主义积极乐观的传统。在这部小说中，他生动地展示了主人公克莱德•格里菲斯短暂而悲惨的一生——他从一个单纯的少年逐渐沦落为无情的杀人凶手并最终被处以极刑。这个故事揭露和抨击了当时美国国民道德的沦丧以及政治和法律制度的腐败。

　　　本文旨在分析造成克莱德悲剧的根本原因及德莱赛的自然主义写作手法。笔者认为，造成克莱德悲剧的原因主要有三点，分别是个人因素，社会因素和家庭因素。首先，克莱德天生的性格缺点让他很容易受外界影响，从而失去自我。其次,社会因素又由三个部分组成，分别是经济影响，文化影响和政治影响。另外，他的家庭对于他的悲剧也是要负责的。他贫穷的家境和父母一贯安于现状的态度，让他迫切地希望改变自己的生活。最终，笔者希望通过分析内外因的作用对人们一生命运的影响能提醒大家树立正确的世界观和价值观的重要性。

关键词：原因；个人的；社会的；家庭的；自然主义