Pouvoir, Savoir, Arriver à: ability vs impossibility

English makes do with one main verb for ability — can, plus be able to for compound tenses. French does not. Where English says can, French distinguishes between general capacity (pouvoir), learned skill (savoir), struggle-and-succeed (arriver à), being-up-to-the-task (être capable de), having-permission-or-right (avoir le droit de), and being-in-a-position-to (être en mesure de) — and each of these has a corresponding negative that says something specific about why the action does not happen.

Choosing the wrong one is not a grammatical error in the strict sense — most of these forms are mutually intelligible — but it is a meaning error. Saying je sais nager when you mean je peux nager communicates skill rather than circumstance. Saying je n'arrive pas à dormir when you mean je ne peux pas dormir communicates struggle rather than impossibility. This page walks through each form, what it actually says, and when to reach for it.

Pouvoir: general capacity, circumstantial possibility

Pouvoir + infinitive is the closest French has to neutral English can. It covers physical ability, circumstantial possibility, and permission — three meanings English also fits into can.

The first sentence is physical capacity, the second is permission, the third is circumstantial possibility — and pouvoir handles all three the same way. When in doubt about which French verb to use for can, pouvoir is the safe default: it will not be wrong, just sometimes less precise.

In the negative, ne pas pouvoir covers the parallel range — inability, prohibition, impossibility:

Savoir: learned skill, knowledge of how

Savoir + infinitive is the verb for skills you have learned. Swimming, driving, cooking, speaking a language, riding a bicycle — anything that required acquisition through practice or instruction. The English I can swim is ambiguous: it could mean I have the skill (learned) or I'm physically able to right now (circumstantial). French splits the two.

The contrast is sharp: je sais nager says I have the skill; je peux nager says I am in a position to swim right now. If you are tired and the pool is closed, je sais nager is still true — je peux nager is not.

In the negative, ne pas savoir + infinitive means not know how, with the implication that the skill was never acquired:

Arriver à: struggle and succeed (or fail)

Arriver à + infinitive is the dynamic ability verb — it implies effort, often struggle, and either success or its negation. The literal sense is to arrive at doing something, with the metaphor of reaching the action across some difficulty. English equivalents: manage to, succeed in, be able to (with effort).

The flavor is dynamic: there is something difficult about the action, and the verb tracks whether the speaker breaks through. The negative is even more frequent than the positive — je n'arrive pas à + infinitive expresses I'm trying and failing, I can't seem to, I'm struggling to.

The contrast with je ne peux pas is sharp. Je ne peux pas dormir says I am physically unable to sleep — perhaps because of pain, noise, or some external constraint. Je n'arrive pas à dormir says I am trying to sleep and not succeeding — perhaps from anxiety, restlessness, or a racing mind. The first is impossibility; the second is unsuccessful effort.

Être capable de: up to the task

Être capable de + infinitive expresses competence or willingness to do something — being the kind of person who can do it. It is closer to English be capable of than can, and it often carries a moral or evaluative weight.

The negative être incapable de + infinitive is strongly evaluative — it says someone lacks the capacity, often with a tone of criticism or limitation:

Avoir le droit de: have the right to

Avoir le droit de + infinitive is about permission and entitlement — having the right or authorization to do something. It is the natural reach when the question is whether something is allowed, not whether it is possible.

This overlaps with pouvoir in permission contexts, but avoir le droit de is more explicit about rules and authorization. Tu peux partir says you can leave (it's possible, you're free); tu as le droit de partir says you have the right to leave (you're authorized).

Être en mesure de: be in a position to (formal)

Être en mesure de + infinitive is a formal register form — diplomatic, bureaucratic, professional. It says be in a position to do something, often used when capacity depends on circumstances or resources. (formal)

This form belongs to administrative correspondence, business meetings, official statements. Using it in casual conversation sounds stilted; reaching for it in a job application or formal email reads as polished.

Avoir du mal à: struggle to

Avoir du mal à + infinitive expresses difficulty doing something — the action happens, or could happen, but with effort, discomfort, or strain. The literal sense is to have trouble (mal) at doing something. English equivalents: struggle to, have difficulty + gerund, find it hard to.

The contrast with je n'arrive pas à is delicate: avoir du mal à implies the action is happening, just with difficulty, while ne pas arriver à implies failure to break through. J'ai du mal à comprendre — I'm understanding, but it's hard. Je n'arrive pas à comprendre — I'm trying but not getting it.

Impossibility: il est impossible de + INF vs il est impossible que + SUBJ

The impersonal construction il est impossible takes two complement structures:

Il est impossible de + infinitive — when no specific subject is implied:

Il est impossible que + subjunctive — when there is a specific subject for the impossible action:

The choice mirrors the broader French pattern: same subject, infinitive; different subject, que + subjunctive. The subjunctive after il est impossible que is required because impossibility is by definition an unrealized state — the trigger is exactly the kind of unreality that drives subjunctive elsewhere.

Choosing the right verb: a quick decision tree

Common Mistakes

Key Takeaways

French unpacks English can into a precision toolkit. Pouvoir is general capacity. Savoir is learned skill. Arriver à is dynamic struggle, often paired with success or its absence. Être capable de is competence with an evaluative tilt. Avoir le droit de is permission. Être en mesure de is the formal-register option. Avoir du mal à is struggling-while-doing; ne pas arriver à is trying-but-failing. The negatives map cleanly onto these distinctions, with il est impossible de / que providing the impersonal frame. Building real B1-level expressiveness means picking the verb that says exactly what you mean — not the one that translates can most directly.