Context: There is an N-magnet and an S-magnet. Nobody and nothing connected the magnets, there was no agent (even there was no wind intervention), but they just connected naturally.
In this case, can I use passive voice as below?
Passive form: “Two magnets were connected.”
And as a result, do “two magnets were connected” and “two magnets (have) connected” have no semantic difference?
Best Answer
There is a class of verbs that have both transitive and intransitive forms, in which the object of the transitive form is the subject of the intransitive. These are sometimes called labile or ergative verbs. The usual example is "to open":
The intransitive form implies there is no agent. The transitive form has an explicit agent.
The passive is formed from the transitive verb, and has an implied agent.
This implies the existence of an unnamed agent.
But we have to be careful with this, because often there is an adjective that looks exactly like a past participle.
So we have "to break":
In the last case the existence of the adjective means that we can't conclude that "somebody broke the window". The word "broken" could be understood as an adjective and that doesn't imply the existence of an agent.
In the case of "open" the adjective is "open", we say "An open door" or "The door was open" when we use the adjective, so the ambiguity doesn't exist.
Now, while "The window was broken" is syntactically ambiguous, it is not usually semantically ambiguous. The meaning is clear.
How about "connect"? Well it is like "break", because there is a valid as an adjective: "Two connected magnets". So the sentence
Can be understood as being [subject] [linking verb] [adjective complement] and no agent is implied.