The perfect tense in English reports past events that continue to have an effect in the present. This leads to some interesting effects that are sometimes called lifetime ‘effects’. This name is used because whether a sentence is acceptable (felicitous) depends on whether it relates to a person or subject that still exists. For example, compare the following sentences:
- * Charles Darwin has visited Australia.
[the asterisk is standard notation for an ungrammatical expression]
- Australia has been visited by Charles Darwin.
The topic of the first sentence is Charles Darwin. Thus, the first sentence could describe how an Australian visit by Darwin is still relevant to his life. But Darwin is no longer alive, so that connotation of continued relevance to Darwin produces a contradiction. This makes the sentence unacceptable.
In contrast, the topic of the second example sentence is Australia. The visit by Darwin could still have some relevance to Australia, so the sentence is acceptable.
This example is from Perfect Tense and Aspect (Marie-Evitz Ritz) in The Oxford Handbook of Tense and Aspect (2012). Actually, although I agree with the substance of her summary, I don’t totally agree with her conclusion on the second example sentence, which I find at best only marginally acceptable. To my ear, because the verb is visit, the focus is more on the fact of a visit having been made rather than on Australia having been affected by the visit(s). And it is not possible for Darwin himself to make any further visits.
So the second sentence would be better in the imperfect tense as: Australia was visited by Charles Darwin. On the other hand, the perfect tense would also be fine in the following variants of the second sentence:
- Australia has been visited by many naturalists, including [Person X, still alive] and Charles Darwin.
- Australia has been affected by a visit made by Charles Darwin.
Implications for using the passive
Example sentences 1 and 2 illustrate that changing a sentence from active to passive changes the topic of the sentence. This change can alter the connotations of the sentence so radically that an unacceptable sentence can become acceptable (or vice versa, of course). This is something to bear in mind in writing and in editing.