Reply to "Determiners and Adjectives"

Is there a definitive, or close to a definitive, decision about whether or not determiners are a subcategory of adjectives?
Hello, Reenie, and welcome to the Grammar Exchange!

I'm sorry it's taken me a while to respond to your question here. I saw it shortly after you posted it and hoped that someone else would reply, as I have had an extremely busy week and didn't have time for a debate.
I was taught that articles are adjectives and that some pronouns FUNCTION as adjectives. But now I read that articles and some pronouns, as well as some quantifies, are all determiners, but NOT adjectives!
If you want to talk about certain pronouns, you need to specify which ones you have in mind. We can't read your mind when you say "some pronouns." I shall assume, however, that by "articles" you mean "the," "a," and "an."

Historically, there have been grammarians who have referred to articles ("the," "a," and "an,") as "limiting adjectives." I am not aware of any grammarians who have taken that position since the dawn of modern linguistics.

Here's why I would never call an article, or any other type of determiner, an adjective:
    1. An determiner is not optional before a count noun.

    (a) He bounced a ball.
    (b) He bounced the ball.
    (c) *He bounced ball.

    2. Adjectives, like all modifiers, are always optional.

    (d) He bounced a red ball.
    (e) He bounced a ball.
    (f) He bounced the red ball.
    (g) He bounced the ball.

    3. Articles and other determiners can't be predicated of nouns; adjectives can.

    (h) The ball is red.
    (i) *The ball is the.
    (j) *The ball is a.
    (k) *The ball is my.

    4. Articles can be followed by adjectives; they cannot be followed by other determiners.

    (l) The ball is red.
    (m) His ball is red.
    (n) *The his ball is red.
    (o) *His the ball is red.

    5) Adjectives can be intensified by intensifiers; determiners and other determiners can't.

    (p) The very red ball is mine.
    (q) *Very the red ball is mine.
    (r) My very red ball is big.
    (s) *Very my red ball is big.
Would you still like to believe that articles (or possessive determiners, like "my," "his," "their," etc.) are adjectives?