According to a certain value standard, the parent item is divided into sub-items belonging to different grades. For example, in the year-end assessment, employees are divided into exemplary, excellent, good, qualified and unqualified grades, and each grade is rewarded with different amounts of bonuses or fines. Due to the infiltration of value judgment and preference factors, classification lacks objectivity and is easy to cause controversy. Use as little as possible, and try to give objective and clear standards when necessary.
Appropriate division shall at least comply with the following rules:
(1) The sum of each child must be equal to the extension of the parent.
Violation of this rule will lead to logical errors in incomplete or excessive projects. For example, if we divide the colors into red, yellow, blue, white and black, we will make the mistake of incomplete items because it omits orange, green, cyan and purple. If we divide literary works into novels, poems, plays, music, dance, painting and sculpture, we will make the mistake of more sub-items, because music, dance, painting and sculpture do not belong to the category of literary works.
(2) Each division can only have one standard.
Violating this rule will make the mistake of confusing the standards. For example, it is correct to divide triangles into equilateral triangles, isosceles triangles and equilateral triangles only according to the length of each side of the triangle; On the contrary, if the triangle is divided into equilateral triangle, unequal triangle and equilateral triangle, it is an incorrect division and makes the mistake of confusing standards, because it uses two different standards this time: one is the case of side length, and the other is the case of inner angle.
(3) The divided sub-items must be mutually incompatible.
Violation of this rule will make the mistake of compatibility of children. For example, if we divide natural numbers into positive even numbers, positive odd numbers and prime numbers, we will make the mistake of item compatibility, because prime numbers are only a part of positive odd numbers, or some special odd numbers, which can only be divisible by 1 and itself, and cannot be divisible by any other numbers. Subitem compatibility is usually the result of confusing standards.
It can be said that classification is a systematic and stable division. Classification is divided into natural classification and auxiliary classification.
The so-called natural classification is based on some profound theory and has great stability. For example, the biological classification system, if arranged from small to large, is species, genera, families, orders, classes, phylum and realm. The classification basis here basically comes from the process of species evolution. In such a classification system, every creature has a definite position and will not change easily. For example, the following figure shows the position of people in the natural classification system:
Mammals
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head
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Ape superfamily
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Gibbon, great ape, hominid.
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Gibbon gorilla chimpanzee hominid fossils
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Homo sapiens fossils
The purpose of auxiliary classification is for convenience and practicality. According to the characteristics of an artificially selected object, it divides the object into different categories, the most typical of which is the book classification of the library. Its purpose is to facilitate readers to find the books they want as soon as possible and provide as many different retrieval methods as possible. The difference between auxiliary classification and general classification lies in its systematicness and stability, which will not be easily changed; Otherwise, it's just division, not classification.
Obviously, division and classification play an important role in scientific theory and our daily life. They keep the world around us in order in our minds.