Personal infinitives versus impersonal infinitives

I just don’t get this unit. Can anyone explain it to me in a way that I can understand? Like I dont understand when you use personal infinitives versus impersonal infinitives. Also, does it change the meaning of the word? Is it necessary to use personal infinitives? What if I cant pick this up?

@daniellamb397, it’s really a difficult topic to grasp, because there’s no correspondence to it in English. It’s also difficult to explain - we gave it our best shot with this Learning Note :smile:

Basically, the infinitive is always the infinitive, whether personal or impersonal. The difference is that by definition, the impersonal infinitive is not linked to any grammatical person and so, it can be used to express ideas that aren’t applied to someone in particular. Note how the following statements are completely general (impersonal):

  • É saudável fazer exercício. = It’s healthy to exercise.
  • É difícil ser imparcial. = It’s difficult to be impartial.

If in a certain context, we want the same ideas to be applied to a given individual, this is where the personal infinitive kicks in, to personalize the statements (without changing their meaning at all, just targeting them specifically).

  • É saudável (tu) fazeres exercício. = It’s healthy for you to exercise.
  • É difícil (nós) sermos imparciais. = It’s difficult for us to be impartial.

In the examples right above, if you explicitly add the personal pronouns (tu, nós), the personal infinitive becomes mandatory. If you omit the pronouns, the personal infinitive is optional - the infinitive can remain impersonal if easier for you. However, the sentences above describe ‘universal truths’, so to speak. If it doesn’t make sense to generalize a certain statement, the personal infinitive also becomes mandatory on a semantic level:

  • Para tu dizeres isso, é porque foi sério. = For you to say that, it’s because it was serious. —> This statement is only true for this specific person; the impersonal infinitive would be grammatically acceptable, but logically incorrect.

The personal infinitive is also mandatory when different subjects are involved throughout a sentence. For example:

  • Eu comprei sopa para (tu) comeres. = I bought soup for you to eat.

Note how we move from a first person to a second person in the second part of the sentence (second clause). Even if we omit the pronoun tu, the infinitive must remain personal if we want the message to be understood. Otherwise, if we use the impersonal infinitive, the understanding is that both actions are performed by the same subject:

  • Eu comprei sopa para comeres = I bought soup for you to eat (personal infinitive - correct)
  • Eu comprei sopa para comer = I bought soup to eat (impersonal infinitive - only correct if the subject is the same; incorrect if it’s supposed to be different)

So, because of this, there are indeed several cases where the personal infinitive is actually necessary and not just a choice. Replacing the personal infinitive (when mandatory) by something else always requires rephrasing the sentence and there’s no single way to do it - it depends on the sentence.

Let’s see some of the examples above without the personal infinitive:

  • Eu comprei sopa para (tu) comeres
    Eu comprei sopa para que (tu) comas (I bought soup so that you eat it) → Switch from personal infinitive to a subjunctive tense - Very advanced!
    Eu comprei sopa para ti (I bought soup for you) → Switch to a simpler sentence - My recommendation :slight_smile:

  • Para tu dizeres isso, é porque foi sério.
    Se tu dizes isso, é porque foi sério. → Switch to the present indicative.


Thank you for your effort to help me. I discovered that I had somehow jumped from working in A2 units all the way to working in Personal infinitives versus impersonal infinitives in B1. I think I’m having so much trouble understanding it because I jumped past so much. I will let you know when I get back there If you have managed to help me.
Thanks for your understanding.

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Olá Joseph

Embora esteja certo de que estão 100% corretos, as duas frases :

• É saudável (tu) fazeres exercício.
• É difícil (nós) sermos imparciais.

não parecem mais naturais se incluirmos uma preposição? Ou seja:

• É saudável para (tu) fazeres exercício.
• É difícil para (nós) sermos imparciais.


Olá, @samarang! As frases já soam totalmente naturais sem a preposição :slight_smile: Ainda assim, a preposição pode ser acrescentada, desde que o pronome pessoal seja modificado para um pronome tónico (porque o conjunto preposição+pronome forma um complemento verbal):

  • É saudável para ti fazeres exercício. (2ª pessoa do singular)
  • É difícil para nós sermos imparciais. (1ª pessoa do plural - neste caso, o pronome tónico é igual)

A preposição também permite mudar a ordem dos elementos da frase:

  • Para ti, é saudável fazeres exercício.
  • Para nós, é difícil sermos imparciais.
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I am so glad you asked about this. I have just finished this unit and I couldn’t understand why you would not just use the infinitive in its usual form so I was really grateful that I was not the only one confused. Joseph’s explanation makes sense of it.

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