Q: If I write “a large, beautiful house,” a comma goes between “large” and “beautiful.” But if I write “a large brick house,” there is no comma between “large” and “brick.” I don’t understand why one phrase has a comma and the other doesn’t. I would be extremely grateful if you could clarify this for me.
A: My rule of thumb is to use a comma between adjectives only (1) if I could use “and” instead, and (2) if the adjectives are reversible.
Let’s look at your first example: “a large, beautiful house.” You know the comma is appropriate because (1) you could use “and” instead of the comma: “a large and beautiful house,” and (2) you could reverse the adjectives: “a beautiful, large house.”
You can’t do that with your second example: “a large brick house.”
The grammatical rule is that you use a comma to separate adjectives if each one has the same relation to the noun. For example, “large” and “beautiful” qualify “house” in the same way, and you could just as easily reverse them or use “and” in between. So the comma is appropriate.
But in the other phrase, “brick” is a different kind of adjective from “large.” It’s part of a cohesive noun phrase: “brick house.” And “large” is an adjective that qualifies the entire noun phrase, so no comma is needed.
Bryan A. Garner, in Garner’s Modern American Usage, puts it this way:
“When adjectives qualify the noun in different ways, or when one adjective qualifies a noun phrase containing another adjective, no comma is used. In these situations, it would sound wrong to use and – e.g.: ‘a distinguished [no comma] foreign journalist'; ‘a bright [no comma] red tie.'”
I hope this helps.