A funny quirk of English I never noticed until I started learning Spanish:

In Spanish, to say for example, "he is a doctor," you would say "él es médico." Which more literally translates to "he is doctor," which feels unintuitive coming from English. Spanish DOES have an equivalent for "a" - "un/una", so the natural thing for an English speaker to say would be "él es UN médico", but I understand that to be awkward/unnatural.

But then I realized, when you say the same sentence in plural - "they are doctors" - you don't have an article. You don't say "they are some doctors" (I had to Google, apparently "some" isn't an article anyway?)

So Spanish ends up more consistent - Singular: "Él es médico." Plural: "Ellos son medicos."

Unlike English - Singular: "He is a doctor." Plural: "They are doctors."

It’s simply that, in English, there is no indefinite plural article — or, equivalently, that the indefinite plural article is null. So ‘they are doctors’ is consistent with the behaviour of plural nouns elsewhere.

Contrast this with, for example, French, where the indefinite singular un(e) correspond to the indefinite plural des: La boulangerie vend des baguettes ‘the bakery sells baguettes’ (whereas English cannot say *‘a baguettes’). But as in Spanish, professions take no article either way: Il est médecin / Ils sont médecins. So all three languages are self-consistent, just in their own ways.

Interstingly it is the same in german, you would say "Er ist Arzt" not "Er ist ein Arzt". Which makes me wonder why english uses an indefinite article there, since it doesn't seem to be either germanic or romantic in origin.

You are right most of the time for English, but today that should be "Arrr! He be the sawbones".

Spain had pirates too, but I don't speak Spanish so had to ask an LLM. It suggested that today in Spanish it would be "Él es el matasanos del barco". Any authentic Spanish pirates who can verify or correct that?

Certainly English can be odd. It can usually be understood through tough thorough thought though.

The further back you go in Indo-European languages, they don't have articles. It's a relatively recent innovation.

So for example latin didn't have them. Eventually they evolved from ille and unus.

Much of Eastern Europe still does not have articles.

There is no plural equivalent of a/an. So where you would use a/an becomes no-article for plural nouns.

You can say "they are the doctors" -- but yeah it's a slightly different meaning.

BTW in German, it's a fun distinction. The old "ich bin (ein) Berliner". (or hamburger or frankfurter...)

I suppose you could say, “they are both doctors” or “they are all doctors.”

Those sound fine to me, depending on context.

Over-learning Portuguese (as a beginner) almost make me feel that "He is a doctor" should become "They are as doctors".

In "They are doctors" the 'they' is the subject and you don't need articles. 'They' is plural.

But in "The doctors are female" you do because the subject is some specific group of doctors. It's singular because its a single group of things.

Is French different? Il est un médecin? Il est médecin? Ils sont médecins sounds fine.