B1 · Intermédiaire Chapitre 31

Entre doute et certitude : Maîtrise l'art de l'hypothèse

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51 exemples
6 min
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Chapter in 30 Seconds

Master the art of expressing uncertainty and logical deductions with professional precision.

  • Differentiate between weak and strong possibilities using modal verbs.
  • Make logical deductions based on evidence using 'must' and 'can't'.
  • Use advanced probability adjectives and adverbs to sound more natural.
Stop guessing, start expressing levels of certainty.

Ce que tu vas apprendre

Tu as déjà eu l'impression de manquer de nuances quand tu n'es pas sûr à 100 % de quelque chose ? C’est tout à fait normal ! Dans ce chapitre, on va transformer ton anglais pour que tu puisses exprimer toutes les nuances de la probabilité, comme un vrai natif. On va commencer par les incontournables may et might pour parler de ce qui est possible. Mais on ne s'arrête pas là ! Tu apprendras à faire de vraies déductions logiques : utilise must quand une preuve te saute aux yeux (comme dire 'He must be tired' après une longue journée) ou can't be quand quelque chose te semble totalement impossible. On ajoutera même une touche d'élégance avec may well pour montrer que tu es plutôt confiant dans tes prédictions. Imagine-toi en train de discuter du dénouement d'une série avec des amis ou d'analyser pourquoi un collègue est en retard à une réunion. Grâce à des structures comme bound to, likely ou probably, tu ne te contenteras plus de mots vagues ; tu sauras exactement comment traduire ton degré de certitude. À la fin de ces 5 leçons, tu auras toutes les clés pour spéculer, déduire et prédire avec une précision chirurgicale. C’est le moment de faire parler ton intuition !

Learning Objectives

By the end of this chapter, you will be able to:

  1. 1
    By the end you will be able to: describe a 30-50% chance of an event happening using may or might.
  2. 2
    By the end you will be able to: conclude that something is definitely true or false based on evidence.
  3. 3
    By the end you will be able to: rank different outcomes from 'unlikely' to 'bound to' using non-modal structures.

Guide du chapitre

Overview

As a B1 English learner, you're moving beyond basic communication and starting to express more nuanced ideas. This is where understanding English possibility and probability becomes incredibly useful! Imagine you're making plans, discussing news, or even just wondering about the weather – knowing how to express how likely something is can really boost your confidence and make your English sound much more natural.
This chapter will equip you with essential tools to talk about uncertainty and make logical deductions.
We'll explore how to use modal verbs like may and might to express things that are simply possible, and how must helps you sound confident about a logical conclusion. You'll also learn handy phrases like may well and might well to express a higher degree of probability. By mastering these concepts, you'll be able to discuss potential outcomes, explain why you think something is true, and even confidently state when something just can't be!
These are all key skills for navigating a wide range of everyday conversations at the B1 English grammar level.
Being able to differentiate between something that *might* happen and something that *must* be true based on evidence will help you communicate more precisely. It's about adding depth to your English, allowing you to share your thoughts and reasoning in a clear and convincing way. Get ready to discuss possibilities and probabilities like a pro!

How This Grammar Works

Let's break down the core grammar rules for expressing possibility and probability in English. We use modal verbs to do this, and they always precede a base verb (the infinitive without 'to').
When you're talking about something that is possible, but not certain, you'll use may or might. They are largely interchangeable for present or future possibility. For example,
It may rain later
means there's a chance of rain.
Similarly,
She might be at the library
suggests it's a possibility, but you're not sure. These express general uncertainty or a 'maybe' situation.
Now, if you're quite sure about something based on evidence or logic, you use must. This isn't about obligation; it's about making a logical deduction. If your friend has been studying all night, you could say,
She must be tired.
You're almost certain based on the clues.
This is called the epistemic must. The evidence makes it highly probable.
To add a bit more strength to your predictions, you can use may well or might well. These phrases indicate that something is quite likely because it makes good sense or there are strong reasons for it. For instance, "If he doesn't study, he may well fail the exam" implies that it's a very probable outcome given his actions.
It's stronger than just may or might alone, suggesting a reasonable expectation.
Finally, when you're absolutely certain that something is logically impossible, you use can't. For example, if you see someone enter a room and then immediately leave through the same door, you could say, "She can't be in the room anymore." The evidence tells you it's impossible. It's the opposite of must for logical deduction.
These structures build on each other, allowing you to express varying degrees of certainty.

Common Mistakes

  1. 1✗ Using 'must' for permission instead of logical deduction in this context.
✓ He must be home, his car is in the driveway. (Correct: Logical deduction)
✗ You must go to the party. (Incorrect for probability; this is obligation. For possibility, you might say
You might go to the party if you want.
)
*Explanation:* Remember that the 'must' we're focusing on here is for making a logical guess, not for giving orders or saying something is required.
  1. 1✗ Confusing 'may' and 'might' for past possibility.
✓ She may have forgotten her keys. (Correct for past possibility)
✗ She might forget her keys yesterday. (Incorrect: 'Might' for past possibility needs 'have' + past participle)
*Explanation:* For past possibility or probability, you need to use may have + past participle or might have + past participle. The chapter focuses on present/future, but this is a common extension.
  1. 1✗ Using 'cannot' instead of 'can't' for logical impossibility in informal contexts.
✓ That can't be true! (Correct: Common and natural)
✗ That cannot be true! (Less natural in everyday, conversational English for this specific meaning, though grammatically correct)
*Explanation:* While 'cannot' is grammatically fine, 'can't' is much more common and natural when expressing logical impossibility in conversational English.

Real Conversations

A

A

The lights are off in John's office. He usually works late.
B

B

He must have left already. It's almost 7 PM.
A

A

Do you think Sarah will come to the party?
B

B

She said she was busy, so she might not make it. But she may well surprise us if her meeting finishes early.
A

A

I can hear music from next door.
B

B

Oh, that can't be my neighbour. He's on holiday in Spain this week!

Quick FAQ

Q

Can I use 'may' and 'might' interchangeably for possibility?

Yes, in most cases for present and future possibility, may and might are interchangeable. Some people feel 'might' expresses a slightly weaker possibility, but the difference is very subtle and often not significant in everyday conversation.

Q

How is 'must' for possibility different from 'must' for obligation?

Must for possibility (epistemic) means

I am almost certain based on evidence
(e.g.,
He must be rich; he drives a fancy car.
). Must for obligation means
It is necessary or required
(e.g.,
You must finish your homework.
). The context makes the meaning clear.

Q

Is 'may well' much stronger than 'may'?

Yes, may well expresses a higher degree of probability than just may. It suggests that something is quite likely because there's a logical reason or expectation for it to happen. It's like saying "it's very likely or it's probable."

Q

When should I use 'can't' instead of 'won't be able to' for impossibility?

Use can't when you're making a logical deduction that something is impossible based on facts or evidence ("That can't be true, I saw it myself!"). Use 'won't be able to' for future inability or lack of opportunity ("I won't be able to come tomorrow, I have an appointment.").

Cultural Context

Native English speakers use these modal verbs constantly to soften statements, express uncertainty, and convey different levels of conviction. In casual conversation, you'll hear might and can't a lot, as they add a natural flow. Must for deduction is also very common.
While may well and might well are perfectly natural, they tend to be slightly more formal or used when explaining a reasoned prediction. There aren't significant regional differences in the core usage of these modals, but the frequency of their use may vary slightly between individuals.

Exemples clés (8)

1

I `may go` to the gym after work, if I'm not too tired.

J'irai peut-être à la salle après le travail, si je ne suis pas trop fatigué(e).

Possibilité en Anglais : May et Might
2

They `might be` stuck in traffic, which is why they're late.

Ils sont peut-être coincés dans les embouteillages, c'est pour ça qu'ils sont en retard.

Possibilité en Anglais : May et Might
3

Look at all the snow! It `must be` freezing outside.

Regarde toute cette neige ! Il doit faire un froid glacial dehors.

Hypothèse Logique avec 'Must' (Épistémique)
4

He's wearing a doctor's coat. He `must be` a doctor.

Il porte une blouse de médecin. Il doit être médecin.

Hypothèse Logique avec 'Must' (Épistémique)
5

She **may well pass** the exam; she studied all week.

Elle **va sûrement réussir** l'examen ; elle a étudié toute la semaine.

Amplificateur de Probabilité : May Well & Might Well
6

The package **might well arrive** tomorrow, as it shipped yesterday.

Le colis **pourrait bien arriver** demain, puisqu'il a été expédié hier.

Amplificateur de Probabilité : May Well & Might Well
7

That pizza place `can't be closed` already, it's only 8 PM!

Ce restaurant de pizzas ne peut pas être déjà fermé, il n'est que 20h !

Impossibilité Logique (Ça ne peut pas être !)
8

My internet `couldn't have gone out`. I just paid the bill yesterday.

Ma connexion internet ne peut pas être coupée. Je viens de payer la facture hier.

Impossibilité Logique (Ça ne peut pas être !)

Conseils et astuces (4)

💡

Utilise-les pour des suggestions polies

Tu veux donner un conseil sans être autoritaire ? Utilise might. Au lieu de dire Fais ça !, tu peux dire
You might want to consider this
pour être plus cool et collaboratif.
frontend.learn_grammar.from_rule: Possibilité en Anglais : May et Might
💡

Cherche les preuves !

Avant d'utiliser 'must' pour une déduction logique, vérifie toujours si tu as des preuves solides. Plus les preuves sont fortes, plus tu peux être sûr avec 'must'. Par exemple, si quelqu'un a les yeux rouges,
She must have been crying.
frontend.learn_grammar.from_rule: Hypothèse Logique avec 'Must' (Épistémique)
💡

Boost Your Predictions

Quand tu parles de l'avenir, 'may well' et 'might well' donnent plus de poids à ce que tu dis. Utilise-les quand tu as une bonne raison de croire que quelque chose va arriver, ça rendra ton discours plus précis et informé.
They may well arrive late due to traffic.
frontend.learn_grammar.from_rule: Amplificateur de Probabilité : May Well & Might Well
💡

Pense à l'opposé

Si tu utilises must be pour une déduction positive forte (par exemple,
He must be rich
), alors "can't be" est son opposé logique. Ça t'aide à bien capter le lien. Par exemple : "He can't be poor."
frontend.learn_grammar.from_rule: Impossibilité Logique (Ça ne peut pas être !)

Vocabulaire clé (6)

Evidence facts or signs that show something is true Likelihood the chance that something will happen Certain completely sure about something Possible able to be done or happen Impossible not able to occur or exist Predict to say what will happen in the future

Real-World Preview

coffee

Solving an Office Mystery

Review Summary

  • Subject + may/might + base verb
  • Subject + must + base verb
  • Subject + can't + base verb

Erreurs courantes

In English, we do not use 'must not' for logical deductions. We use 'can't' to say something is logically impossible.

Wrong: It must be not true.
Correct: It can't be true.

Modal verbs like 'might' never take an 's' in the third person singular.

Wrong: He mights come to the party.
Correct: He might come to the party.

Adverbs of probability like 'probably' usually go after the first auxiliary verb or before the main verb.

Wrong: Probably I will see you later.
Correct: I will probably see you later.

Next Steps

You've unlocked a new level of English! Being able to speculate and deduce makes your conversations much more interesting. Keep practicing those 'must be' moments!

Look out the window and make 5 'must be' and 5 'might be' observations about people you see.

Continue to: Le secret du naturel : maîtrisez les duos de mots

Pratique rapide (10)

Choose the correct sentence.

Which is correct?

✓ Correct! ✗ Not quite. Correct answer: I will probably go.
Probably before verb.

frontend.learn_grammar.from_rule: Probability: Likely, Unlikely, Bound To, Definitely, Probably

Trouve et corrige l'erreur

Find and fix the mistake:

If you don't save, you might as well run out of money.

✓ Correct! ✗ Not quite. Correct answer: If you don't save, you might well run out of money.
'Might well' indique une forte probabilité de manquer d'argent si tu n'économises pas, alors que 'might as well' suggère de le faire comme option.

frontend.learn_grammar.from_rule: Amplificateur de Probabilité : May Well & Might Well

Quelle phrase exprime correctement une déduction logique sur un événement passé ?

Choose the correct sentence:

✓ Correct! ✗ Not quite. Correct answer: They must have missed the bus.
Pour les déductions logiques sur des événements passés, la structure correcte est 'must have' + participe passé.

frontend.learn_grammar.from_rule: Hypothèse Logique avec 'Must' (Épistémique)

Fix the error.

Find and fix the mistake:

He is bound that he wins.

✓ Correct! ✗ Not quite. Correct answer: He is bound to win.
Bound to + infinitive.

frontend.learn_grammar.from_rule: Probability: Likely, Unlikely, Bound To, Definitely, Probably

Choisis la forme correcte pour exprimer une impossibilité logique.

He's only 16, so he ___ a licensed driver yet.

✓ Correct! ✗ Not quite. Correct answer: can't be
Puisqu'il n'a que 16 ans, il est logiquement impossible qu'il soit déjà un conducteur agréé (dans la plupart des pays). 'Can't be' exprime cette impossibilité.

frontend.learn_grammar.from_rule: Impossibilité Logique (Ça ne peut pas être !)

Choisis la forme correcte pour compléter la déduction logique.

The lights are off and the door is locked. She ___ asleep.

✓ Correct! ✗ Not quite. Correct answer: must be
Pour une déduction logique au présent, utilise 'must' suivi de la forme de base du verbe 'to be'.

frontend.learn_grammar.from_rule: Hypothèse Logique avec 'Must' (Épistémique)

Trouve et corrige l'erreur dans la phrase.

Find and fix the mistake:

They mustn't be home. Their car isn't in the driveway.

✓ Correct! ✗ Not quite. Correct answer: They can't be home. Their car isn't in the driveway.
'Mustn't be' est incorrect ici. L'interlocuteur fait une déduction logique basée sur une preuve (la voiture n'est pas là), donc 'can't be' est le bon choix pour exprimer l'impossibilité logique.

frontend.learn_grammar.from_rule: Impossibilité Logique (Ça ne peut pas être !)

Trouve et corrige l'erreur dans la phrase.

Find and fix the mistake:

They might to forget about our meeting.

✓ Correct! ✗ Not quite. Correct answer: They might forget about our meeting.
Les verbes modaux (might) sont directement suivis par la forme de base du verbe principal (forget), sans to.

frontend.learn_grammar.from_rule: Possibilité en Anglais : May et Might

Choisis la forme correcte pour compléter la phrase.

She ___ be at the library right now, I'm not sure.

✓ Correct! ✗ Not quite. Correct answer: may
May est un verbe modal et ne change pas de forme. Il est suivi par la forme de base du verbe (be).

frontend.learn_grammar.from_rule: Possibilité en Anglais : May et Might

Quelle phrase est correcte ?

Choose the correct sentence:

✓ Correct! ✗ Not quite. Correct answer: He may well succeed.
L'ordre des mots correct pour cette expression est 'may/might well + verbe de base'. L'intensificateur 'well' vient directement après le verbe modal.

frontend.learn_grammar.from_rule: Amplificateur de Probabilité : May Well & Might Well

Score: /10

Questions fréquentes (6)

L'idée principale, c'est d'exprimer que quelque chose est possible ou probable, mais pas totalement certain. Ça te permet de spéculer ou de faire une supposition sans t'engager à une affirmation définitive, comme
It may rain later
(Il pourrait pleuvoir plus tard) ou
She might be busy
(Elle pourrait être occupée).
Dans la plupart des contextes modernes pour exprimer la possibilité, oui, ils sont largement interchangeables. Même si might peut parfois suggérer une probabilité un peu plus faible, la différence est souvent très subtile et pas toujours respectée dans le langage courant. Donc pas de stress !
It may happen
ou
It might happen
sont souvent pareils.
Il s'agit de faire une déduction forte et confiante basée sur les preuves que tu as. Tu dis : 'Étant donné X, Y must be true' car c'est la seule conclusion logique. Par exemple, si tu vois quelqu'un courir sous la pluie,
He must be in a hurry.
Très sûr(e) ! Pense à une probabilité de 95-99%. Tu utilises 'must' quand les preuves sont si fortes que la conclusion semble presque indéniable, comme : 'The lights are off, so he must be asleep.' (Les lumières sont éteintes, donc il doit être endormi.)
'May well' signifie que quelque chose est très probable, plus sûr qu'un simple 'may'. Ça implique une raison logique à cette probabilité accrue.
It may well be true.
Ils sont largement interchangeables pour une forte probabilité. 'Might well' peut parfois être un peu plus hésitant ou utilisé pour des situations hypothétiques, mais l'idée principale de forte probabilité reste la même.
She might well be busy right now.
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Et si tout était possible ? Maîtrise le second conditionnel
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