The two phrases “tu en penses quoi” and “qu’est-ce que tu en penses” are common in everyday language, but they do not belong to the same register. Understanding what distinguishes them requires analyzing the role of the pronoun, the verbal construction, and the level of language expected by the communication context.
Grammatical construction of the verb penser: pronoun “en” and preposition “de”
The verb “penser” changes meaning depending on the preposition that follows it. “Penser à quelque chose” means to think about something, to reflect on it. “Penser de quelque chose” means to have an opinion, to formulate a viewpoint.
When asking for someone’s opinion, the correct construction is “penser de”. The pronoun “en” replaces the complement introduced by “de”. Saying “qu’est-ce que tu en penses?” is equivalent to saying “what do you think about that?”.
| Formulation | Verbal construction | Register | Grammatical correctness |
|---|---|---|---|
| Qu’est-ce que tu en penses ? | penser de + pronoun “en” | Standard / common | Correct |
| Qu’en penses-tu ? | penser de + pronoun “en” + subject-verb inversion | Formal | Correct |
| Tu en penses quoi ? | penser de + pronoun “en” + “quoi” at the end of the sentence | Familiar | Correct (oral) |
| Tu penses quoi ? | penser without pronoun or preposition | Very familiar | Grammatically incomplete |
The formulation “tu penses quoi?”, without the pronoun “en”, is grammatically incomplete because the prepositional complement is missing. The verb “penser” used to ask for an opinion requires the preposition “de”, which the pronoun “en” replaces. An article detailing what you think about spelling confirms this grammatical analysis.
Familiar register or formal register: which form to choose in writing
The real dividing line between these formulations is not strict correctness, but register. The first three forms in the table above are all grammatically acceptable. What varies is their degree of formality.
“Qu’en penses-tu?” remains the only form suitable for formal writing: professional correspondence, administrative writing, essays. The inversion of the subject and verb is the marker of the formal register in French interrogative sentences.
“Qu’est-ce que tu en penses?” is suitable for common writing: emails between colleagues, messages on a forum, blog articles. The structure “est-ce que” has long belonged to the standard register.
“Tu en penses quoi?” places the interrogative word “quoi” at the end of the sentence, which characterizes the familiar register. This form is heard everywhere in daily conversation. Contemporary oral grammars describe it as extremely frequent and perfectly functional in speech, without labeling it as incorrect.
Why “quoi” at the end of the sentence is perceived as familiar
In standard French, the interrogative word is placed at the beginning of the sentence (“que penses-tu?”) or after “est-ce que” (“qu’est-ce que tu penses?”). When “quoi” remains in the position of the complement, the sentence retains the subject-verb-complement order of spoken French. It is this lack of displacement that signals the familiar register.
The structure “subject + verb + quoi” has become widespread in informal speech since the 2000s. We say “tu fais quoi?”, “tu regardes quoi?”, “tu manges quoi?” without anyone seeing it as an error in conversation. The form “tu en penses quoi?” follows exactly the same mechanism.
Conjugation of the verb penser: common errors in writing
With the issue of register settled, another trap awaits in writing: conjugation. The verb “penser” is a regular first-group verb, but confusion between the indicative and subjunctive causes recurring errors.
- In the present indicative, we write “tu penses” with a final -s. This is the form used in direct questions: “qu’est-ce que tu en penses?”.
- In the present subjunctive, we write “que tu penses”, still with an -s. The spelling is identical, which reduces the risk of error for this specific verb.
- In the present imperative, second person singular, we write “pense” without -s. Confusion with the indicative is common: “pense à ce que tu fais” and not “penses à ce que tu fais”.
The most common error is writing “pense” without -s in the indicative (“tu pense quoi?”), confusing the imperative form with that of the indicative. The rule is simple: in the indicative and subjunctive, the second person singular always takes an -s for first-group verbs.
The case of subject-verb inversion and the hyphen
In the formal form “qu’en penses-tu?”, a hyphen links the verb to the inverted subject pronoun. Forgetting this hyphen is a common spelling mistake. The rule applies to all questions with inversion: “veux-tu?”, “sais-tu?”, “crois-tu?”.
Penser “de” or penser “à”: two meanings not to be confused
One last source of confusion deserves to be isolated. “Penser de” and “penser à” are not interchangeable.
- “Penser de” introduces an opinion: “qu’est-ce que tu penses de ce film?” means “what is your opinion about this film?”.
- “Penser à” introduces an idea, a memory, an intention: “tu penses à quoi?” means “what are you thinking about?”.
- The pronoun “en” replaces “de quelque chose” (opinion), while the pronoun “y” replaces “à quelque chose” (reflection). Saying “tu y penses?” means “are you thinking about it?”, not “what is your opinion?”.
Confusing “en” and “y” amounts to confusing asking for an opinion and asking what someone is thinking about. The sentence “qu’est-ce que tu y penses?” is incorrect if one wants to solicit an opinion.
The choice between “tu en penses quoi”, “qu’est-ce que tu en penses” and “qu’en penses-tu” depends on the communication context, not on an absolute correctness rule. All three forms respect the grammar of the verb “penser de”. The only truly incorrect form is the one that omits the pronoun “en”, as it removes the link with the preposition “de” that the verb requires to express an opinion.