如同汉语一样，英语也经常使用双重否定来表示肯定的含义。其中but表示that (who) not，整句话意思可解释为：There is no rule that has not any exception. 即 Every rule has exceptions. 上一句通过双重否定 (double negation) 或 加重否定 (cumulative negation) 的no和but的连用来加强语势;而正面说法的语气较弱。
　　大家再来看下以下几个例句：
　　There is no one of us but wishes to remove all the illegal dangerous structures in Hong Kong.
　　我们大家都希望拆除香港所有违章建筑的危楼。
　　There is no one but knows it.
　　此事无人不知。
　　There has not been a scholar but was a man of industry.
　　凡是有学问的人都是勤奋的。
　　There is no man but errs.
　　凡是人都会犯错的。
　　比较下面两句句子意思：
　　There is no one who knows him.
　　There is no one but knows him.
　　在下面句子中，but是从属连词，不是关系代词：
　　It never rains but it pours.
　　不雨则已，一雨倾盆
　　Not a day but it rains.
　　没有一天不下雨。
　　下面的句子也属于双重否定举行，它们也具有加强语势的修辞效果：
　　No language is more exempt from error and obscurity than the language of mathematics.
　　任何语言都比不上数学语言那么精确和明了。
　　He never goes to college without dropping in at the school library.
　　他每次去大学都要去图书馆转一圈。
　　She never fails to attract people’s attention.
　　(相比not fail的结构上过新概念的同学应该非常熟悉的)
　　再来看一下一些包含双重否定的英语谚语，他们都表达了强化肯定的涵义：
　　No sweat without sweat.
　　梅花香自苦寒来 (当然此句上课时我也说过可以翻译成Adversity leads to prosperity. 前后押韵)
　　No smoke without fire.
　　无风不起浪
　　Nothing is impossible to a willing heart.
　　有志者事竟成 (Where….., there…….)
　　另外补充一下but作动词的特殊用法：
　　But me no buts. (上课时说过，忘记的同学快去查下字典吧!)
　　最后回到原句: There is no rule but has exceptions. 他的意思就非常明显了。
　　(但是这句话本身是一个谬论，推理过程如下：
　　1.Every rule has an exception. (Statement)
　　2."Every rule has an exception" has an exception. (By 1)
　　3.There exists some rule R without exception. (By 2)
　　4.Since R is a rule, by the first statement it must have an exception. But by 3, it does not have an exception - an apparent contradiction.
　　5.)括号中为扩展阅读内容，对翻译本身没有关系，just for fun!