I like this question.
Actually, "il connaît son métier" can work for "he knows his (or) her job". It means that he knows how to do his own (in most cases), or someone else's job (another man's or "her") but with a risk of not being very clear.
"Il sait son métier" is not grammatically incorrect, but to avoid any ambiguity, we would say it differently:
"Il sait quel métier il/elle fait" or "il sait quel est son métier" - in that case, it will always be someone else's job.
In this case, the reason for "connaître" goes with the meaning of "to be knowledgeable about something". Usually such a sentence is a compliment.
To get a better grasp of your other suggestions, I added some context:
Il sait faire son travail quand ça l'arrange = he knows to do his job when it suits him.
Il sait comment faire son travail, et il le fait bien = he knows how to do his job, and he does it well.
yes and no. what I was going for is, that if somebody talked about me saying "il connaît son métier", I would feel insulted, because I am not just familiar with my job, but I actually know what I'm doing. thus I would prefer being referred to as "il sait son métier". "il connaît son métier" sounds to me like a subtle way to say: he is a dabbler. But I assume it is an idiom.
If you remember that "connaître" is used with places and people, you will also understand the notion of "deep/extended knowledge" (connaissance profonde/étendue), which is also included in "connaître".
Don't feel insulted: "un métier" is a noble word, and "je sais son métier" only means that I know what he's doing for a living, not that I could do his job.
Could you please explain the "s'y" part in your first sentence.
I think it's contraction of "si + y" but it doesn't click in my mind.
- 'si' could mean 'if, so, yes' depending on different usage, but they didn't make sense to me.
- what is the adverbial pronoun 'y' replacing here??
The "s' " is the reflexive pronoun "se" (il se connaît)
The "y" is elliptic and would refer to the field of knowledge.
- il connaît beaucoup de choses en astronomie = il s'y connaît en astronomie.
- colloquial: il y connaît quoi, en astronomie ? or il y connaît quoi, à l'astronomie ?
However, it is nearly "undecipherable" because the "s' " is not really justified. Just another weird idiomatic expression, I'm afraid.
Wow! I didn't even consider the reflexive pronoun as it still doesn't make any sense being reflexive in what!
But, as you said, it is an idiomatic expression; so we need to take it as is.
The adverbial pronoun 'y' is somewhat interesting here.
I always learned that 'y' replaces 'à + noun', and to me "beaucoup de choses" looks like the direct object of the verb 'connaît'.
Doesn't it make more sense to replace it with a direct object pronoun??
I've never encountered a phrase with a reflexive pronoun and a direct object pronoun, it's probably going to be ridiculously weird, and that's the reason for using 'y', or is there any grammar involved here??
I have found some more info, and I edited my previous message accordingly.
Actually "il se connaît à XX" was the ancient reflexive phrase, that evolved with time and became "il s'y connaît en XX" (= he has a good knowledge of XX).
Therefore, "y" and "en XX" represent the same thing in "je m'y connais en XX".
- est-ce que tu t'y connais en astronomie ?
- oui, je m'y connais.
"y" is therefore an indirect pronoun.
@Sitesurf: "I have found some more info, and I edited..."
It's interesting how thing change in time.
Different constructions evolve and leave a simple trace that will eventually feel like an idiom that doesn't make sense at all.... but it's good to know the roots of such expressions
Some ambiguity here. In a previous q Duo would not accept job for"metier". Now it does. The comments for that q pointed out that job and profession are somewhat different. Can a native speaker comment on whether the problem is with this q accepting it, or the other one not accepting it?
From French to English, this sentence can have a number of translations, like: he knows what he is doing; he knows his craft, his trade, his business... or his job.
"Un métier" is not a job, on principle. Un métier is a combination of knowledge and experience, whereas "un emploi" (job) is basically about work for money.
- You can be jobless and have "un métier".
- You can have "un métier" and a job that is not your "métier", like a software engineer giving math lessons.
From English to French, "he knows his job" would mostly translate to: "il connaît son travail" or "il sait ce qu'il fait"
Hey, Sitesurf, in this sentence, "il connaît son métier,'' is it true that you do not pronounce the the "t" in "connaît" because the next word starts with a consonant? If I can remember, the pronunciation of the final letter (if it is a consonant) depends on the first letter in the next word.
The trouble is the use of the word 'craft' has been really changing in the last few decades in the UK. Its traditional use is becoming quite outdated. Hence 'Arts & Crafts' and 'Craftwork' have rather pushed out 'he knows his craft', etc. In fact, I am sure that some young people would be puzzled by this meaning. It is just how language evolves. Everyday words to cover this include skill,- very skilled at his/her job; a skilled trade/job.