C’est vs Il est le fils de Martha

Question

I don’t get why “C’est le fils de Martha” translates to “He is Martha’s son.” 
Well, I should probably restate that: I read the lesson, so I know what the rule is, but I don’t understand the logic behind it. 
In English, using “c’est” would never make sense because “Il” means “he.” Thus, it would always be “Il est le fils de Martha.” 
How would the sentence need to be phrased so that “il est” would be correctly used (instead of c’est)? Or is this not possible (because an article will always be used)? 
 
In this case, you wouldn’t be referencing an “it,” but an actual (specific) person instead. Something like: 
1. Qui est Roger? / Il est le fil de Martha. (The example with Sylvie contradicts this because it also uses c’est.)
or
 
 
2. Qui est le garçon? / Il est le fil de Martha (because il is referring to a specific boy) 
 
Hopefully that makes sense. Thanks in advance! 😊

Céline Pickard · Accepted Answer

Bonjour Jasmine,
The main thing to remember is what kind of word follows the verb (if there's an article or not). It has nothing to do with how specific or identified the person is.
Remember the pattern:
- If there is an article ("He/She/ It is + a/the/my... + [noun/name]") -> Use "c’est + [article] + [noun]"

C'est le fils de Marie = He is Marie's son
C'est son fils = He is his/her son
C'est un professeur = He/She is a teacher

- If you are expressing a simple statement/opinion -> Use "il/elle est + [X] + adjective etc" -> without an article

Elle est gentille = She is nice
Il est français = He is French
Il est professeur = He is a teacher

Therefore:
- Qui est Roger ? - C'est le fils de Martha. = - Who is Roger? - He is Martha's son. 
-Qui est le garçon ? - C'est le fils de Martha. = - Who's the boy? - He is Martha's son.
 
I hope this is helpful.
Bonne journée !

Fulya Ozata · Answer

In most cases, if the noun has an article or another determiner, French usually prefers c’est. If there is no article, French often prefers il/elle est.

For example:

C’est le fils de Martha.

C’est un médecin.

C’est mon frère.

But:

Il est médecin.

Il est français.

Il est intelligent.

There is one important nuance: Il est le fils de Martha is not impossible or ungrammatical. It can be used when il already clearly refers to someone and you are giving additional information about him:

Roger habite à Paris. Il est le fils de Martha.

However, if you are identifying someone in answer to a question such as Qui est Roger ?, French strongly prefers:

C’est le fils de Martha.

A useful shortcut is:

c’est + noun with an article/determiner
il/elle est + adjective or profession/nationality without an article

This is not an absolute rule, but it works very well in most everyday situations.French commonly uses c’est + noun phrase for identification:

Qui est le garçon ? — C’est le fils de Martha.

You would be more likely to use il est le fils de Martha when the boy has already been established in the conversation and you are simply adding information about him:

Tu vois ce garçon là-bas ? Il s’appelle Roger. Il est le fils de Martha.

Hope this helps :)