lze / nelze + Infinitive

Impersonal Possibility with Lze and Nelze

Level 5

The words lze (it is possible) and nelze (it is impossible) are used to express objective feasibility. They are always followed directly by an infinitive.

How It Works

Although often translated into English using modal verbs ("can" / "cannot"), lze and nelze are not verbs. They are invariable predicative words.

Key characteristics:

  • Morphology: They never conjugate for person or number (e.g., you cannot say já lzu).
  • Syntax: They attach directly to an infinitive. Unlike je možné, they cannot take a že clause directly as their subject. However, they are frequently followed by one indirectly via verbs of communication or cognition (e.g., Lze předpokládat, že...).
  • Verbal Aspect: Lze and nelze can be paired with both perfective and imperfective infinitives. While perfective verbs are common for expressing the possibility of achieving a specific result, imperfective verbs are extremely frequent, particularly verbs of cognition, communication, and perception (e.g., lze předpokládat, lze očekávat, lze pozorovat).
  • Word Order: While lze often starts a sentence, the word order is flexible. The infinitive phrase can easily precede lze for topicalization or emphasis (e.g., Tomu se vyhnout nelze.).
  • Clitic Placement: When lze or nelze starts a sentence, second-position (Wackernagel) clitics like se, si, or short pronouns immediately follow it (e.g., Lze se tomu vyhnout.).
  • Impersonal Nature: These expressions are strictly impersonal and objective. In modern standard Czech, they are not used with a dative pronoun to express general personal ability (e.g., you do not say nelze mi to udělat for 'I cannot do it'). However, colloquially, native speakers sometimes use a dative experiencer for technical glitches (e.g., Nelze mi otevřít soubor - 'I can't open the file').
  • Case Assignment: The infinitive phrase acts as the subject of the sentence. Because the infinitive is an active verb, its direct object must be in the accusative case (e.g., Lze podat žalobu [Acc]). Note the contrast with the alternative dá se + infinitiv, which is a reflexive passive construction where the object becomes the nominative subject (e.g., Dá se podat žaloba [Nom]). Although prescriptively dá se takes the nominative, in casual spoken Czech, native speakers frequently blur this rule and use the accusative anyway (e.g., dá se podat žalobu).
  • Register: This pattern is highly formal, academic, and official. It is extremely common in journalism, legal texts, and manuals, but almost never used in casual spoken Czech. For everyday speech, native speakers use dá se + infinitiv or jde + infinitiv.
  • Tense and Mood: To express the past, future, or conditional, it requires the copula být (bylo lze, bude lze, bylo by lze). However, these forms sound highly archaic, literary, or hyper-formal today. In modern Czech, it is much more natural to switch to bylo/bude/bylo by možné or forms of dá se + infinitiv for other tenses and moods.

Examples (5)

  1. Tuto možnost nelze vyloučit.

    This possibility cannot be ruled out.

    Word by Word: This possibility [Acc] it-is-impossible to-rule-out.

    Notice that 'tuto možnost' is in the accusative case, acting as the direct object of the infinitive 'vyloučit'.

  2. Pohovku lze rozložit na postel.

    The sofa can be converted into a bed.

    Word by Word: Sofa [Acc] it-is-possible to-unfold into bed.

    A typical instruction manual sentence. 'Pohovku' is in the accusative case.

  3. Lze předpokládat, že omezení bude mít pozitivní dopad.

    It can be assumed that the restriction will have a positive impact.

    Word by Word: It-is-possible to-assume that restriction will to-have positive impact.

    A classic example of academic hedging. The construction projects an aura of objective fact.

  4. Zde nelze parkovat.

    Parking is not possible here. / One cannot park here.

    Word by Word: Here it-is-impossible to-park.

    A common official sign or instruction. It uses an intransitive verb, so no object is needed.

  5. Tento problém lze vyřešit několika způsoby.

    This problem can be solved in several ways.

    Word by Word: This problem [Acc] it-is-possible to-solve by-several ways.

    Because 'problém' has the same form in the nominative and accusative, it looks like a subject, but grammatically it is the accusative object.

Common Mistakes

  • Using the nominative case instead of the accusative for the logical object.

    Ta chyba nelze vyloučit.
    Tu chybu nelze vyloučit.

    Because English uses a passive subject ("The error cannot be ruled out"), learners often mistakenly put the Czech noun in the nominative. However, in Czech, the infinitive phrase acts as the subject, and the noun receiving the action is the direct object of that active infinitive, meaning it must be in the accusative case.

  • Using a dative pronoun to express general personal inability.

    Nelze mi to udělat.
    Nemůžu to udělat.

    In modern standard Czech, 'lze' and 'nelze' are impersonal and describe objective possibility. They are not used with a dative experiencer to mean general personal inability like 'I cannot do it'. To express this, use the verb 'moci' (e.g., 'nemůžu') or the phrase 'nejde mi'. Note, however, that colloquially, native speakers sometimes use a dative pronoun for technical glitches (e.g., 'Nelze mi otevřít soubor').

  • Using 'lze' in casual, everyday conversation.

    Different MeaningLze tady sedět?
    Dá se tady sedět?

    While grammatically correct, using 'lze' in a casual setting sounds extremely unnatural, like reading from a legal document. In everyday speech, use 'dá se' or 'jde'.

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lze / nelze + InfinitiveLevel 5Impersonal Possibility with Lze and Nelze

Learn This First

To learn 'lze/nelze + infinitiv', a learner must first understand the basic concept of expressing possibility (usually through the verb 'moci'). They also need to be familiar with standard verb negation and how infinitives function when following modal-like expressions, including the choice of verbal aspect.

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lzenelze