Earlier quoted context omitted.
"A" and "the" are most certainly the same part of speech. There are many other words in the same category: many every my some his this Note that "my", "his", and "this" also mark definiteness on the noun phrase.
> "A" and "the" are most certainly the same part of speech. I disagree... > There are many other words in the same category: All these example words add semantic meaning to the noun phrase, and a primary sub-category for their use is whether the noun is countable (e.g. cat) or uncountable (e.g. salt): cats VS salt a cat/any cat, some cats, all cats/every cat VS some salt, all salt no cats, one cat, two cats, ... VS n…
There's some guy out on the sidewalk erasing the chalk art.
It's more common to use "a" there, but not required.Here are two English sentences in which a word appears solely to satisfy English syntactic requirements:
Your house is big.
It's raining outside.
While interesting, those sentences aren't arguments that "is" is not a verb, or that "it" is not a noun.