The cognitive logic of “one divides into three” also discussion on the nature of engineering

Scholars in China and western countries entitle the term “engineering” different meanings, in this paper the logical principle of “one divides into three” is proposed and it is the precondition to define a study object. And a three-stage thinking mode is suggested to get a comprehensive understanding of a thing, also, the relationship of the three thinking stages is analyzed, and the “one divides into three” mode which could be used to analyze the structures and functions of thing is brought out. Finally, the characteristic of “engineering” is analyzed under this logical principle, and “engineering” is viewed as a life system.