2. The physicist rightly dreads precise argument，since an argument that is convincing only if it is precise loses all its force if the assumptions on which it is based are slightly changed，whereas an argument that is convincing though imprecise may well be stable under small perturbations of its underlying assumptions. (5+)
物理学家恐惧于那些精确无误的论据不无道理，因为某种只有在它是精确无误的条件下才令人置信的论据，一旦它赖于建立其上的假设稍有变化，便会失去它一部的作用;而与此相反，一个尽管并不精确无误但却令人置信的论据，在其基本假设(underlying assumption)稍微受干扰的情况下，仍然有可能是站得住脚的。
难句类型：复杂修饰
解释：本句在文章中就是一个自然段，虽然长度比不上前面第一章中所举的那个长达10行的例子，但是难度绝不在那句话之下。本句堪称句子的大杂烩，连主句带从句居然一共有八个。从大往小说，由whereas连接了两个大句子，whereas后面的句子中的主语an augument之后又跟了一个定语从句that is convincing though imprecise， 修饰augument。whereas前面共有六个句子，由the physicist作主语的主句;由since引导的原因状语从句，修饰since从句中主语an augument的由that引导的定语从句，此定语从句中的条件状语从句only if it is precise; since从句中的条件状语从句if the assumptions on which it is based are slightly changed,以及修饰此从句中的主语assumptions的定语从句on which it is based一共八个句子，从句套从句，实在令人叹为观止。