材料工程专业英语---UNIT NINE-LESSON TWO.ppt

LESSON TWO FUNDAMENTALS OF PAPER WRITING (Ⅱ)
The Fourth Method: Definition
A dictionary will give you two different definitions of the word definition: (l) "a statement of what a thing is" and (2) a "a statement or explanation of what a word or phrase means or has meant. " In the strict sense, a definition, as we shall use the word here, is not of a thing, but of a word, or of a process.
The process of making a definition is not, however, a mere game of words. It is clear that we cannot make a useful definition without knowledge of the “thing”(that is, object, event, idea, etc.) to which the word (or term) refers. And it is equally clear that the definition of a municates knowledge about the "thing" referred to. A definition does give knowledge of "what a thing is, " and equally important, may lead the maker of definition to clarify his own thoughts on the nature of the "thing."
In fact, a description can often serve as a definition: by enlightening us about a thing, it enlightens us about the use of the term that refers to the thing. For example, we find later in this chapter a description of the mechanism used to lift liquids, and when we have finished reading that, we know how to define the term jet pump. But for the moment, we are not concerned with description as a form of definition, nor concerned with certain other kinds of definition (for instance, what is known as recursive definition in arithmetic and grammar). We, instead, are concerned with traditional, or classic, definition, which goes back as far as Aristotle. Our discussion is confined to that form.
A definition locates its subject in a class and then proceeds to point out the characteristics that make it differ from other items in that class and that, therefore, allow it to be assigned to a subclass. This process is, it is clear, a special variant of the process of classification. A definition simply sets its subject in a limited scheme of classification.
The process of definition is, like cla