Passive voice

[Ashis]

Hello friends. I've a question about spanish passive voice. My confusion is between use of impersonal se and use of ser + past participle. For example, here is two sentence ;

1) Peter no se ha visto desde el viernes.
2) Este libro fue escrito por mi tía.

I can not understand where to use impersonal se and where not? or use of impersonal se and ser + past participle are interchangeable? Can anyone explain this? THANKS in advance.

[Perikles]

Hello friends. I've a question about spanish passive voice. My confusion is between use of impersonal se and use of ser + past participle. For example, here is two sentence ;

1) Peter no se ha visto desde el viernes.
2) Este libro fue escrito por mi tía.

I can not understand where to use impersonal se and where not? or use of impersonal se and ser + past participle are interchangeable? Can anyone explain this? THANKS in advance.I'll have an amateurish attempt:

Basically Spanish avoids the passive voice whenever it can, and the actual passive voice is seen as more formal. They use the passive reflexive construction when the agent is either undefined or not an issue, as in your sentence 1) above. Other examples would be

Se celebrarán las elecciones en marzo
Se rechazó la propuesta

But when the agent is significant, the passive voice is unavoidable, such as your 2) above.

This may seem a bit odd when you see thing like Las pirámides se edificaron por esclavos, but here the agent, the slaves, are not so important.

But you would say este cuadro fue pintado por Picasso:good:, but not este cuadro se pintó por Picasso:bad:.

In short, the examples like your 1) are far more common than 2).

Perhaps others may disagree. :)

[aleCcowaN]

1) Peter no ha sido visto desde el viernes.

or

1) A Peter no se lo ha visto desde el viernes.

but not "Peter no se ha visto ..." (¿al espejo?) "...desde el viernes".

[Viernes, if you still are going to call it "Viernes" in one month. If you are saying "desde el viernes" and later "desde hace cuatro viernes", it's "viernes"]

Perikles' explanation is very good. I'd only add that, a), we use passive voice in Spanish when it is significant to depict some kind of process or operation done over the subject, and b), we keep in mind that "se" may imply some degree of reciprocal action; that's why "Fueron vendidos diez zapallos" is correct but it sounds "incorrect" as the operation of selling pumpkins is not like changing their destiny by submitting them into slavery, and there's no possibility that by saying "se vendieron diez zapallos" one may suspect that the pumpkins sold each other -if such were the case, is suffices to say "se vendió diez zapallos" (you can't say "fue vendido diez zapallos:bad:" and that may explain some differences between pasiva refleja and pasiva común)