The Synchrony and Diachrony distinction in language description

Some insights into the nature of language can be gained by examining its history that means examining it diachronically, and some can be gained by assuming synchronic viewpoint.
The kind of information that we can expect from the two approaches can be represented by two kinds of section of the trunk of a tree.


- Horizontal section: Reveals kind of information that is similar to what synchronic study of language can reveal.
It shows particular stages of states of language that can be compared and are distinguishable from each other. For examining this data we do not need any knowledge about previous history. We can locate, define and describe items by relating them to items within this item.


You do not need to know etymology of a word to use it. You do not need to know what inflectional systems shaped the words to use them correctly.



- Vertical section: Can show only a thin slice of items corresponding to the historical development of a single set of units in the synchronic state.
The historical approach can be only used to study the development of any set of linguistic forms when we are informed about:
a) systematic relations of these forms in an earlier state of language
b) differences to be found in their systematic relations at a different state of language.
e.g., a cut of an ''English tree'' at one period would reveal presence of a certain number of nominal inflections but another cut of the same tree at present time would show fewer such inflections.