【正确答案】这在目前是得到公认的，尽管是个人见证的论述，而较少有严谨的科学推理作为证据的基础。

【答案解析】[结构分析] 句子框架是it is generally accepted，although...。主句中代词it代指前句内容it is no longer necessary that...this idea(有关这一主题的所有演讲或书籍不必用支持这一观念的证据开头了)。although引导让步状语从句，省略了主语和谓语，补充完整为although it is generally accepted more as a self-evident statement than on the basis of a closely reasoned scientific proof。more...than...结构意为“不是…，而是…；与其说…，倒不如说…”。