Modals of Deduction — Must, Can’t & Might (B2)

Modals of Deduction

Use must, can’t and might to say how certain you are — without guessing wildly

From Sourov’s world: As a sommelier at Sydney’s finest restaurants, I was trained to read a wine before the label was revealed. I’d lift the glass to the light: deep garnet, barely any orange rim — this wine must be young. Then the nose: blackcurrant, tight tannins, no secondary earthy notes yet — it can’t be more than five years old. A faint cedar whisper — it might be a Bordeaux blend. Three levels of certainty, three different modals. You do the same thing every time you read a situation and decide how sure you are.

📚 Language Focus

Meaning — three degrees of certainty (present deduction):

Form: modal + be / base verb (no -s, no infinitive to)

• She must be tired. (NOT must is)
• He can’t know the answer yet. (NOT can’t knows)
• They might be waiting outside.

CCQs: Are we 100% sure? → No, so we use a modal. Do we think it’s impossible? → can’t. Do we think it’s almost certainly true? → must. Are we unsure either way? → might / could.

💡 Examples

🍷 Sommelier situations → English grammar

• The colour is very pale — this wine can’t be a full-bodied red. (almost certain it’s NOT)
• There’s a strong floral aroma — it must be a Riesling. (almost certain it IS)
• I detect a hint of oak — it might be aged in barrels. (possible — not sure)

🏨 Hotel & restaurant contexts

• That guest ordered sparkling water three times — he must be very thirsty.
• She’s wearing a suit and carrying a clipboard — she might be from head office.
• The kitchen light is off — the chef can’t be still working.

✏️ Quick Check

Fill in must, can’t or might. There may be more than one possible answer — think about your level of certainty.

1. She speaks six languages fluently — she _______ be a professional interpreter.
2. The lights are off and the door is locked — they _______ be home.
3. I’m not sure, but that _______ be our new manager — I’ve never met him.
4. He’s run a marathon every year for twenty years — he _______ be incredibly fit.
5. The wine is bright purple with no browning — it _______ be more than two years old.

🗣️ Try It Yourself

Look at someone nearby — a person on the train, in a café, or in a photo. Write 3 sentences of deduction about them using must, can’t and might. Focus on evidence: what you can actually see or hear. Then explain your reasoning to a partner.