Are there rules that can be followed with plural or is it meant to be this way?

In my quest to learn something new, I started with simple ones where I come across this poem "Why English is hard to learn":

We'll begin with box, the plural is boxes,
But the plural of ox is oxens, not oxes.
One fowl is a goose, and two are called geese,
Yet the plural of moose is never called meese.

You may find a lone mouse or a house full of mice;
But the plural of house is houses, and not hice.
The plural of man is always men,
But the plural of pan is never pen.

If I speak of a foot, and you show me two feet,
And I give you a book, would a pair be a beek :
If one is a tooth and a whole set are teeth,
Why shouldn't two booths be called beeth ?

If the singular's this and the plural is these,
Should the plural of kiss be ever called keese ?

We speak of a brother and also of brethren,
But though we say mother, we never say methren.
Then the masculine pronouns are he, his and him;
But imagine the feminine ... she, shis and shim!

I am enjoying the beauty of this language. It would be great if anybody can clarify why plural in English language this way. Are there rules that can be followed with plural or is it meant to be this way.

Solution 1:

I don't think poems like this (or e.g. The Chaos by Gerard Nolst Trenité) are very helpful for teaching information about English to learners. I think their main goal is to amuse or surprise the reader, not to effectively transmit information.

In fact, English plural formation is pretty simple compared to many other languages. German and Arabic have much more complicated ways of marking plural nouns. In English, the great majority of nouns form a plural with the suffix -s or -es. These nouns are considered "regular" in terms of pluralization. The rules about how to write and pronounce that suffix are the most important thing to know about pluralization.

Nouns ending in -f(e) generally take the regular plural suffix, but may show a slight irregularity: the -f(e) /f/ can change to -ve- /v/. Depending on the noun, it may be obligatory, optional, or forbidden to change -f(e) to -ve- in the plural. I don't know of any easily memorized rule that tells you what behavior to expect from nouns ending in -f(e).

A minority of nouns have a plural form that looks the same as the singular. There tend to be some similarities in meaning between these nouns (e.g. many refer to animals), which might be worth knowing, but I don't know how useful it is to consciously try to memorize facts like this as "rules". I think exposure to English speech and text will help learners acquire the correct usage of nouns like deer and sheep.

An even smaller set of nouns have a special plural form that is different from the singular, but that doesn't end in -(e)s. These nouns are considered to pluralize "irregularly": men, geese, mice, oxen all fall into this category. This category of nouns is small, so it's easy to memorize each specific word with an irregular plural like this: you don't need to know rules for how to form them.