Inflection and Its Types

Inflection is the change in form of a word or addition to a word that influences its use in a sentence. It is simply a modification of words that make them reflect new meanings. For example; when the verb "to be" is inflected to reflect the second person, the verb form changes from "be" to "are". "are" being the inflected form of the verb "to be". Inflection is the process of applying grammatical properties to a word that makes it correspond to the contexts in which it appears. Like the example given earlier, the verb from "be" is changed to "are" to correspond with the second person plural subject.

Inflections are necessary as they are crucial to grammaticallity in sentences. Take for instance:

*I is a boys.

The sentence above is neither grammatical, nor does it make sense. The reason is because the forms of the words do not agree with each other—they do not reflect the relationship that should exist between them in the context of their co-occurrence. Hence with the proper application of inflection, it would read thus;

I am a boy. 

The subject being singular makes it a prerequisite for the accompanying verb to be in singular form as well as reflect the person of the subject —first person. Not only that but also the predicative noun phrase "a boy", not "a boys" is necessary because as a description of the subject, it must correspond with the number of the subject which is singular.

Inflections, contrary to what many believe, is not limited to verbs alone. In fact nouns, pronouns, and adjectives can also be inflected. Hence there are two forms of inflection namely: Conjugation and Declension.

Conjugation

Conjugation is a form of inflection that affects verbs only. It is the inflection of verb forms to reflect: person, tense, and number. Just as the example given above: "I am a boy." The verb form "am" rightfully corresponds with the first person singular pronoun "I", reflecting the tense of the declaration (present), as per the demands of subject—verb agreement principles. Other examples include;

1. He was here.

2. They live downtown.

3. It has been raining.

4. It is just an inflection.

Declension 

Declension, in slight contrast, is the inflection of nouns, pronouns, and adjectives. Nouns are usually inflected to represent person, case, possession and number. For example;

John is a Babyface.

"John" , in the sentence, is the subject (case), singular (number), and third person (person). This inflection of the noun "John" rubs off on the accompanying verb "is" which becomes conjugated to reflect the grammatical properties of the noun.

Nouns are not the only non-verbs that can be inflected—pronouns can be inflected too. Pronouns are inflected for; person, number, possession, and case just like the nouns they replace in sentences. For example;

He likes Indian food.

"He" is a third person singular masculine pronoun, which is also a subject. It is the inflectional properties of the subject that determines the conjugation of the accompanying verb "likes". To illustrate examples in the object positions;

He gave his to me.

Here we have three different inflectional forms of the third person singular masculine pronoun "he", where "he" is subject, "his" is possessive, and "his" is objective case. It can very well be deduced from this that only subjects determine the conjugation of verbs in a sentence.

Adjectives, then, are inflected to represent varying degrees of comparisons. For example; fast, faster fastest; strong, stronger, strongest, etc. So adjectives are inflected to reflect certain degrees of comparison namely: Comparative (used to compare), and superlative (above the chart, incomparable).

Some instances; 

1. I am faster than you.

2. I am best at winning bets.

The first instance, "faster", is an adjective form inflected to reflect comparison between two entities: "I" and "you". The other adjective "best" is inflected to reflect the highest degree that can not be compared. 

So inflections are really just varying changes to words or additions to them that influence there use in sentences. It is also the embedding of grammatical qualities in words to ensure grammaticality of instances of language use, being of two types : Conjugation and Declension.