When do I use connaître and when do I use savoir?

A basic rule of thumb often tought is that savoir is used with facts and connaître is used with people/places.

I'd like to propose a slightly revised version of this rule of thumb:

  • If you're talking about knowing a person/place, as in 'I know Paul', 'I know London', then use connaître. More specifically, these are cases where you can't easily re-formulate your sentence with a 'question-inside-a-sentence' (see below).
  • In other cases, you can generally use either verb.

By 'question-inside-a-sentence', I'm talking about the difference between a verb phrase and a noun phrase. In many sentences, it is possible to express a similar meaning with either a verb phrase or a noun phrase:

do you know where he lives? vs
do you know his address?

I don't know how old he is vs
I don't know his age

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Contrast these with sentences such as I don't know London, do you know Paul.' It's not obvious what verb phrase (or 'question-in-a-sentence') you'd replace London or Paul with to get a similar meaning.

Coming back to French, an essential difference between the two verbs is that:

  • The verb savoir can be followed by a verb phrase, whereas connaître cannot.

So what does that mean? Well, it concerns sentences where savoir can be used when you have a 'question inside a senetnece':

est-ce que tu sais quelle âge il a?
do you know how old he is?

je ne sais pas à quelle heure son train va arriver
I don't know what time her train's going to get here

je ne sais pas où il habite
I don't know where he lives

je ne sais pas ce qu'il en pense
I don't know what he things of it

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In these cases, you can't use savoir without also changing the rest of the sentence. In other words, French people don't say:

est-ce que tu connais quelle âge il a?

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However, if you form sentences with a similar meaning but where a simple noun phrase is involved, then connaître is generally possible:

est-ce que tu connais son âge?
do you know how old he is?

est-ce que tu connais l'heure d'arrivée prévue de son train?
do you know what time her train is due to arrive?

je ne connais pas son adresse
I don't know where he lives, I don't know his address

je ne connais pas son opion la-dessus
I don't know what his opinion is on that

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The underlined phrases in French are noun phrases and don't contain a verb. (But purely as a matter of translation, you'll see from these examples that it's common to translate them using a verb in English.)

Note that these sentences are referring to pretty much 'the same facts': the difference in verb is grammatical rather than to do with whether or not the object is a fact or place.

 French grammar index
 French-English dictionary
 English-French dictionary

This page written by Neil Coffey. Copyright © Javamex UK 2017. All rights reserved.