I am confused, the following examples are from the Oxford dictionary, all from the same entry (2). Why in some cases it is "a command" and in some it is treated as uncountable?
‘he had a brilliant command of English’
‘For much of the season, he has struggled with command of his
fastball.’"They come with a very basic command of English, " she said.’ ¨
He has good command over English, Punjabi and Hindi languages.’
Best Answer
I don't have an authoritative analysis but it might help to think of it like this: 'command' is uncountable. That's true for all of your sentences. It's certain adjectives that pull in the 'a'. Notice that your sentences only include 'a' when 'command' has an adjective: "a brilliant command", "a basic command". Not all adjectives require the article ("good command"), although "a good command" could also be correct. The point is that you should be looking at the adjective for the origin of the 'a', not the noun. In this case, 'a' is making no assertions about the countability of the noun, or indeed of the adjective.
So what is the relationship between 'a' and the adjective? As a quantifier, it functions not as "one", but rather as a synonym for "some" (possibly as a determiner). It signifies existence. It contrasts with "none at all"; not with two or three. 'a' here implies the opposite of:
In "a sense of direction", direction is uncountable, but it means "some sense of direction" as opposed to "no sense of direction". Similarly, "she has a charismatic personality" and "he has a unique style".
I'm sure there are exceptions, but hopefully this intuition helps.