Every field of study makes the student memorize many words to which the field attaches special meanings. It is done because precise concepts are necessary. First we need carefully expressed concepts to carry on a scientific discussion. The sociological concepts are necessary for a clear discussion of social phenomena. The formulation of concepts leads to increased knowledge. Some accurate descriptive knowledge must be organized before a concept is framed.
Then the analysis and criticism of this new concept point up the gaps and errors in present knowledge. Use of the concept often calls attention to the facts and relationships which may have been overlooked. While studying migration Park framed the concept of the marginal man who is on the fringes of two groups or two ways of life while fully belonging to neither.
The use of this concept quickly led to the recognition that there were many kinds of marginal persons- the persons of mixed racial ancestry who belongs clearly to neither race, the supervisor who is clearly either management or labour the ambitious climber no longer in the lower class yet not securely a middle class person and many others. Concepts like marginality lead to increased knowledge. Concepts are useful as verbal shorthand. The term control group replaces an entire sentence. Every discipline develops concepts as time savers. Most of the concepts of sociology are expressed in words which also have a popular meaning. Every science appropriates some common words and makes them into scientific concepts by giving them a specific definition and sociology is no exception.