The words of the lang. are divided into gr. classes which differ in formal and semantic features. Traditionally they are called parts of speech (p/of/sp). This term is purely conventional and was introduced in the gr. teaching of Ancient Greece. The problem of the p/of/sp is the most controversial one.
1 Principle The Semantic Approach
In many schools the semantic principle was used for p/of/sp classification. It is based on the universal forms of human thought which are reflected in 3 main categorial meanings of words: substance, process, property.
In Medieval linguistics (Пор-Рояль, 1660) p/of/sp are defined as invariants of the substance-logical plane.
However, this principle is open to criticism:
· it doesn’t always work; it can be hard to define a categorial meaning of a word e.g. whiteness - is it substance of a noun or property of an adjective?
· action – it denotes process, but it isn’t a verb
2 Principle The Formal Approach
Only form should be used as a criterion for the classification of the p/of/sp. (Henry Sweet) They distinguished between two classes of words: