Passive versus generic active agent

Czech offers three main ways to handle sentences where the agent is either unknown, general, or deemphasized.

1. The Generic Active
This structure is common in everyday communication but also frequently appears in formal contexts like journalism. You simply use the 3rd-person plural form of the verb and drop the pronoun oni. In the past tense, the participle always takes the animate masculine plural ending -i (e.g., Ukradli mi auto - My car was stolen). Crucially, the patient of the action remains in the case assigned by the active verb. While this is often the accusative, it can be other cases depending on the verb (e.g., dative for pomohli mi or genitive for všimli si toho). It translates to 'someone' or 'they' in English, keeping the sentence dynamic. Additionally, Czech frequently uses the 2nd-person singular (dropping the pronoun ty) or the noun člověk for general rules and statements (e.g., Tady si nevybereš - You can't choose here). The generic active is also the most common grammatical option for inherently reflexive verbs (verbs that already have se or si in their dictionary form, like smát se or ptát se), as they cannot form a reflexive passive and generally lack a periphrastic passive.

2. The Reflexive Passive
Formed with the word se, the reflexive passive is the preferred and most natural choice in spoken and casual Czech, though it is also widely used in formal writing. It works for general rules (Tady se mluví česky) as well as specific, completed actions (Už se to vyřešilo). Unlike the generic active, if the verb takes an accusative object, the patient of the action becomes the grammatical subject in the nominative case (e.g., Dům se staví - dům is in the nominative). However, objects in other cases (dative, genitive, instrumental) remain in their original case within an impersonal construction (e.g., Věří se mu). Keep in mind that se is a clitic and must occupy the second position in the clause. It has two strict limitations: First, it is restricted almost exclusively to the 3rd person and generally to inanimate subjects. Using it in the 1st or 2nd person, or with 3rd-person animate subjects, usually creates a literal reflexive meaning (Myji se means 'I wash myself', not 'I am washed'; Otec se myje means 'Father washes himself'). Second, you cannot attach a human agent to it. A sentence like Dům se staví dělníky is ungrammatical. However, you can express the instrument or means used to perform the action using the instrumental case (e.g., Břemeno se zvedá jeřábem). Furthermore, it can be used without a grammatical subject as an impersonal construction. In spoken Czech, it is very common to use the dummy pronoun to in these constructions when referring to a general action or situation (e.g., To se neříká - One doesn't say that; Jak se to dělá? - How is it done?). When used this way in the past tense, the verb takes the default neuter singular ending -o (e.g., Rozhodlo se, že... - It was decided that...).

3. The Periphrastic Passive
Formed with the auxiliary verb být and a passive participle, this structure sounds more formal, bureaucratic, or literary. Unlike the reflexive passive, the periphrastic passive is the only passive structure that grammatically allows you to explicitly state the human agent using the instrumental case (e.g., Dům byl postaven dělníky). Alternatively, to avoid ambiguity when an instrument is already present in the sentence, the human agent can be expressed using od + genitive (e.g., Pracovník byl vyznamenán diplomem od ředitele). Furthermore, the passive participle must agree in gender and number with the subject (e.g., Dům byl postaven [masculine] vs. Kniha byla napsána [feminine]). If you need to express a passive action in the 1st or 2nd person, you must use this form or rephrase using the generic active. Like the reflexive passive, the periphrastic passive can also be used impersonally with the neuter singular ending -o (e.g., Bylo rozhodnuto). Crucially, the periphrastic passive is generally restricted to transitive verbs (verbs that take a direct object). In contrast, the reflexive passive is more flexible and frequently used with intransitive verbs to form impersonal general statements (e.g., Tady se spí dobře - One sleeps well here).

4. The Role of Verbal Aspect
The choice between the reflexive and periphrastic passive is heavily influenced by verbal aspect. The reflexive passive is strongly preferred for imperfective verbs to describe an ongoing process (e.g., Dům se staví - The house is being built). The periphrastic passive is preferred for perfective verbs to describe a resulting state (e.g., Dům byl postaven - The house was built). Using the periphrastic passive with imperfective verbs (e.g., Dům byl stavěn) is highly bookish and unnatural in everyday speech.