它的前一句是If people are regarded only as machines guided by logic,as they were by some"scientistic"thinkers,retoric is likely to be held in low regard;for the most obvious truth about rhetoric is that it speaks to the whole person.
后一句是Logical argument is the plot,as it were,of any speech or essay that is respectfully intend to persuade people.
就只翻中间那句就行，给这两句是给一下上下文可能有助于理解...希望得到贴合这个语境的翻译。