Sarah couldn't play again because she's broken her arm

[jutfrank]

For example, I just can't imagine an American English speaker saying, "I can't make it to the party tonight because I've broken my leg."

The person who wrote this seems to lack imagination. Or at least not be very observant as to what other American speakers actually might say. Remember that what you're calling 'American English' is nothing more than a major generalisation of a multitude of different language patterns.

I'm sure that in British English, this would have to be "because my car's broken down."

Definitely not. The use of the past tense would mean that the event is viewed as a past event, that's all.

If the present perfect tense is about present relevance, then the British sense of present relevance is different from the American one.

It's not really different but rather that it's less noticeably expressed in American English, precisely because Americans are more inclined on average to use the past simple instead.

 

[Piscean]

If I use the Pres. Perfect or Piscean switches to Simple Past in defiance of our variants' standards, guess what happens to him or me? Nothing, because it's unlikely to even register with any other native speaker.

So true!

 

[EngLearner]

Megan, I can't make it to the game because my car broke down. I'm in the middle of nowhere, so call me back, okay? Thank you.

The car broke down at most 10 minutes ago, but the simple past is used. I'm sure that in British English, this would have to be "because my car's broken down."

It doesn't have to be that.

Definitely not. The use of the past tense would mean that the event is viewed as a past event, that's all.

I can't come with you because I've broken my leg. (It doesn't matter how long ago I broke it; what matters is that it's in a cast and hasn't healed yet.)

Megan, I can't make it to the game because my car's broken down. I'm in the middle of nowhere, so call me back, okay? Thank you. (It doesn't matter how long ago my car broke down; what matters is that it's still broken down and hasn't been repaired yet.)

If we define present relevance as a present state that has resulted from a past action, then it seems logical to use "has broken down" in the sentence about the car. Why present it as a past event if it has present relevance? This would make the car example inconsistent with the broken leg example.

If present relevance is not defined as a present state resulting from a past action, how should I think of it?

 

[Piscean]

I can't come with you because I've broken my leg. (It doesn't matter how long ago I broke it; what matters is that it's in a cast and hasn't healed yet.)

I can't come with you because I broke my leg. (I am not going to risk going on the skiing trip.)

Megan, I can't make it to the game because my car broke down. I'm in the middle of nowhere, so call me back, okay? Thank you.

(What matters is that I am stuck in the middle of nowhere.)

 

[EngLearner]

I'm a little confused. The version I wrote with "has broken down" also makes sense, right? After all, the broken down car is the problem she's dealing with as she speaks.

Does the version with "broke down" mean that she has accepted the fact that she won't make it to the game, while the one with "has broken down" implies that she's calling Megan because she believes Megan might somehow help her with her car, making it possible for her to get to the game on time?

 

[Piscean]

I'm a little confused. The version I wrote with "has broken down" also makes sense, right?

Yes

Does the version with "broke down" mean that she has accepted the fact that she won't make it to the game,

Not in itself, though the co-text makes that clear.

while the one with "has broken down" implies that she's calling Megan because she believes Megan might somehow help her with her car, making it possible for her to get to the game on time?

You can choose to infer that.


You are trying to read too much into the use of a tense/aspect in an unplanned statement.

 

[jutfrank]

If we define present relevance as a present state that has resulted from a past action, then it seems logical to use "has broken down" in the sentence about the car.

Yes, right.

Why present it as a past event if it has present relevance?

One reason may be because you don't want to present its present relevance. Using the past tense is often a good way to simply to present an action as historical.

My car broke down =something happened in the past
I can't come with you = the present result

This would make the car example inconsistent with the broken leg example.

If present relevance is not defined as a present state resulting from a past action, how should I think of it?

Perhaps you're looking for some kind of fast rule whereby if something has any knd of present relevance then a speaker has to use the present perfect. That's not the case. Using the present perfect is not an obligation but just a way of making the present relevance clear to your listener. This is why there are some differences in usage between American speakers and others.