Comme si (as if) introduces a counterfactual comparison: a way to describe how something appears, sounds, or behaves by likening it to a situation that is — explicitly — not the case. Il parle comme s'il savait tout (he talks as if he knew everything) tells us two things at once: that the speaker is acting a certain way, and that the basis for that behaviour is fictional.
The construction is grammatically tight: only two tenses are allowed after comme si, and the conditional is absolutely forbidden. The pattern mirrors the si-clause patterns of conditional sentences (Type 2 and Type 3), but lives a quietly separate life — comme si is a comparative marker, not a conditional one. This page lays out the two patterns, the prohibition, the subtleties of when to use each, and the most common B2 errors.
The two patterns
Just two tenses appear after comme si: the imparfait for a counterfactual that is simultaneous with or relevant to the moment of comparison, and the plus-que-parfait for a counterfactual that is anterior to it.
| Pattern | Tense after comme si | Time relation |
|---|---|---|
Comme si
| Imparfait | Counterfactual at the moment of comparison |
Comme si
| Plus-que-parfait | Counterfactual prior to the moment of comparison |
These are the only two options. The conditional is forbidden, the futur is forbidden, the subjunctive is forbidden, the present is forbidden. Comme si is one of the few constructions in French where the tense slot is locked at exactly two values.
Comme si + imparfait — present counterfactual
Use the imparfait when the as-if situation is being likened to the current moment, the current state of affairs, or the moment the main-clause action is happening.
Il parle comme s'il savait tout sur le sujet.
He talks as if he knew everything about the subject. (he doesn't)
Elle me regarde comme si j'étais un fantôme.
She's looking at me as if I were a ghost.
Tu agis comme si rien ne s'était passé entre nous.
You're acting as if nothing happened between us.
Il fait comme s'il ne me reconnaissait pas, alors qu'on a dîné ensemble la semaine dernière.
He's acting as if he didn't recognise me, even though we had dinner together last week.
In each case, the imparfait carries the same unreal meaning that it carries in si + imparfait hypothetical conditionals (si j'avais le temps — see hypothetical-conditionals-three-types). The imparfait here is what grammarians call l'imparfait modal — a non-past use of the imparfait to mark hypotheticality.
The main clause itself can be in almost any tense — present, passé composé, futur, imparfait — depending on what the speaker is describing.
Il a réagi comme s'il connaissait déjà la réponse.
He reacted as if he already knew the answer.
Demain, elle nous accueillera comme si rien n'était.
Tomorrow she'll greet us as if nothing had happened.
The main-clause tense is independent. Only the comme si clause is locked to imparfait or plus-que-parfait.
Comme si + plus-que-parfait — past counterfactual
Use the plus-que-parfait when the as-if situation is being likened to a past event — something that supposedly happened before the moment of comparison.
Elle a réagi comme si elle avait déjà compris la blague.
She reacted as if she had already understood the joke.
Il s'est levé d'un bond, comme s'il avait été piqué par une guêpe.
He leapt to his feet, as if he had been stung by a wasp.
Tu me parles comme si je t'avais offensé, mais je ne sais pas ce que j'ai fait.
You're talking to me as if I had offended you, but I don't know what I did.
Il a serré sa fille dans ses bras comme s'il ne l'avait pas vue depuis des années.
He hugged his daughter as if he hadn't seen her in years.
The plus-que-parfait stacks two layers of pastness: the as-if event is presented as having happened before the past moment of comparison. This is the same logical structure as si + plus-que-parfait in counterfactual past conditionals, transposed into the comparative frame.
The iron prohibition: never the conditional
The single rule that catches every English-speaking learner at comme si is this: the conditional is forbidden. Just as les si n'aiment pas les rais in conditional clauses, comme si refuses the -rais endings.
❌ Il parle comme s'il saurait tout.
Incorrect — conditionnel after 'comme si' is ungrammatical.
✅ Il parle comme s'il savait tout.
He talks as if he knew everything.
❌ Elle a réagi comme si elle aurait compris.
Incorrect — conditionnel passé after 'comme si' is ungrammatical.
✅ Elle a réagi comme si elle avait compris.
She reacted as if she had understood.
The reason the prohibition feels surprising to English speakers is that English as if takes a counterfactual subjunctive that, in formal English, looks like the past or past perfect (as if he were rich, as if he had known) and in informal English often defaults to would (as if he would know). The French equivalent uses the imparfait or the plus-que-parfait, never the conditionnel.
How does French differ from English?
English uses three distinct constructions for as-if:
- As if + simple past / past subjunctive: as if he knew, as if she were rich. This is the formal English form.
- As if + past perfect: as if he had known. Past counterfactual.
- As if + would + base form: as if he would know. Informal, often considered nonstandard.
French collapses (1) and (3) into comme si + imparfait and uses comme si + plus-que-parfait for (2). The conditional is removed from the table entirely.
As if he knew. → Comme s'il savait.
As if she were rich. → Comme si elle était riche.
As if he had known. → Comme s'il avait su.
The mapping is clean once you accept the prohibition on the conditional. English speakers should default to comme si + imparfait unless the meaning is clearly anterior, in which case comme si + plus-que-parfait.
Choosing between the two patterns
The choice depends on when the counterfactual situation supposedly takes place relative to the main clause.
Imparfait — when the unreal state is concurrent with the action being compared.
Il me parle comme si j'étais sourd.
He talks to me as if I were deaf. (right now, this conversation)
The being deaf is a state simultaneous with the talking. Imparfait.
Plus-que-parfait — when the unreal event allegedly preceded the action being compared.
Il s'est mis à crier comme si je l'avais frappé.
He started shouting as if I had hit him.
The hitting is presented as having allegedly happened before the shouting. Plus-que-parfait.
The choice is rarely ambiguous in practice — the time relation is usually clear from context.
Subtleties and idiomatic uses
Faire comme si
The expression faire comme si (to act as if) is one of the most common collocations in conversation. It can stand alone as a complete idea — fais comme si (just pretend) — without any subordinate clause.
Si jamais il te demande des nouvelles, fais comme si.
If he ever asks about you, just play along.
Il a tout entendu, mais il fait comme si de rien n'était.
He heard everything, but he's acting as if nothing happened.
The fixed phrase comme si de rien n'était (as if nothing were the matter) is highly idiomatic and worth memorising as a unit.
Comme s'il en pleuvait
A set phrase: comme s'il en pleuvait — literally as if it were raining them — meaning in great quantity, in profusion.
Il y avait des pommes comme s'il en pleuvait dans le verger.
There were apples in the orchard like you wouldn't believe.
This is a frozen idiom; you don't conjugate around it.
Negation inside comme si
Negation is fully available and works as you'd expect — ne...pas in the imparfait or plus-que-parfait clause.
Il fait comme s'il n'avait jamais entendu parler de moi.
He's acting as if he had never heard of me.
Tu me regardes comme si je ne disais que des bêtises.
You're looking at me as if I were only talking nonsense.
Comme si in elevated and literary registers
In literary writing, comme si sometimes appears with the subjunctive imparfait or plus-que-parfait. This is a hyper-formal alternative — recognition only, never produced in conversation or in standard B2 writing.
Il parlait comme s'il sût toute la vérité. (literary)
He spoke as if he knew the whole truth. (very literary)
In modern French this would be comme s'il savait. The literary form survives in some twentieth-century writers and in deliberately archaising prose; treat it as a register marker rather than a productive option.
Comme si vs comme
A quick disambiguator: comme alone (without si) introduces a real comparison — like / as. Comme si introduces a counterfactual comparison — as if. Different mood requirements.
Il parle comme un avocat.
He talks like a lawyer. (he is one, or he sounds like one — real comparison)
Il parle comme s'il était avocat.
He talks as if he were a lawyer. (he isn't — counterfactual)
The first sentence implies the speaker really sounds like a lawyer or really is one. The second sentence implies the speaker is not a lawyer but acts as if he were. The grammatical difference (no si vs si + imparfait) tracks the semantic difference (real vs counterfactual).
Comme si and si in conditionals — same prohibition, different work
Both si (in conditional clauses) and comme si (in comparative clauses) refuse the conditional and accept only specific tenses. But their semantic work is different.
| Construction | Function | Allowed tenses |
|---|---|---|
| Si in conditional | Sets up a condition for a consequence | Présent / Imparfait / Plus-que-parfait |
| Comme si | Compares a situation to a counterfactual | Imparfait / Plus-que-parfait |
Both refuse the conditional. Si in real conditionals additionally accepts the present (because the condition might genuinely be met); comme si never does, because the comparison is by definition counterfactual. There is no real-comparison version of comme si — it is locked to unreality.
Common Mistakes
The errors below are the patterns that English-speaking learners produce most often.
❌ Il parle comme s'il saurait tout.
Incorrect — conditional is forbidden after 'comme si'.
✅ Il parle comme s'il savait tout.
He talks as if he knew everything.
The cardinal error. Many learners hear as if he would in informal English and produce the conditional. French does not allow it.
❌ Elle a réagi comme si elle a compris.
Incorrect — passé composé is not allowed; for past counterfactual, use plus-que-parfait.
✅ Elle a réagi comme si elle avait compris.
She reacted as if she had understood.
The passé composé a compris would describe a real past event. Comme si refuses real-event tenses and demands the unreal pluperfect.
❌ Il fait comme s'il ne sait pas.
Incorrect — present tense is not allowed after 'comme si'.
✅ Il fait comme s'il ne savait pas.
He's acting as if he didn't know.
The present is grammatical only after comme (real comparison) or in si-clauses of real conditionals. Comme si requires the imparfait for present-counterfactual readings.
❌ Tu me parles comme si je serais un enfant.
Incorrect — conditional after 'comme si'.
✅ Tu me parles comme si j'étais un enfant.
You're talking to me as if I were a child.
A particularly common version of the conditional error with the verb être. The imparfait étais is the only correct option.
❌ Comme s'il aurait su, il serait venu.
Incorrect — both halves wrong: 'comme si' refuses the conditional; this is also a confused syntax.
✅ Comme s'il avait su, il serait venu.
As if he had known, he would have come.
When the comme si clause refers to a past counterfactual and the main clause is a real past consequence, the structure is comme si + plus-que-parfait + main clause in conditionnel passé. The conditional only enters via the main clause; comme si itself remains plus-que-parfait.
Key Takeaways
- Comme si takes only two tenses: imparfait for present-counterfactual, plus-que-parfait for past-counterfactual.
- The conditional is absolutely forbidden after comme si. Learn it with the same rigour as si je serais (forbidden in conditional si-clauses).
- English's as if + would — common in informal speech — does not translate; reach for the imparfait instead.
- The literary subjunctive imparfait after comme si (comme s'il sût) is recognition-only; never produce it.
- Comme alone introduces a real comparison (like / as); comme si always introduces a counterfactual one.
Now practice French
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning French→Related Topics
- Les Phrases Conditionnelles: les Trois TypesB1 — The three patterns of French conditional sentences — real, hypothetical, and counterfactual past — with the tense pairings, the iron rule that 'si' never takes the conditionnel, and the high-frequency English transfer errors learners must unlearn.
- Les Trois Types de Si: drillingB1 — The full architecture of French conditional sentences: real, hypothetical, and counterfactual — with the strict tense pairings that make them work.
- Comme si: The 'As If' Construction with Imparfait and Plus-que-parfaitB2 — Comme si introduces a counterfactual comparison — and despite what English speakers expect, it never takes the conditional. Imparfait for present-counterfactual, plus-que-parfait for past-counterfactual. This page drills the system.
- L'Imparfait in Si-Clauses: Hypotheticals, Suggestions, and WishesB1 — How the imparfait pairs with the conditional to express counterfactual hypotheses, and how 'si + imparfait' alone proposes plans, regrets, and wishes.
- Plus-que-parfait in Si-Clauses: Past CounterfactualsB1 — The third type of French conditional pairs si + plus-que-parfait with the conditionnel passé to express what would have happened if the past had been different. Past unreal hypotheses about events that didn't actually occur.