Is there a name for this usage of the question mark?

Suppose in some informal medium (like a message board, or chat room, say) somebody claims in writing that “activity X is difficult, so we should all adopt technique Y”, for instance. Dubious, somebody else writes “Activity X isn’t difficult?”, refuting the premise of the original claim. No specific question is being asked (though perhaps it is being used to request clarification), but the question mark is being used to mark suspicion, incredulity, etc.

Is there a specific term for this common usage of the question mark?

I don’t recollect ever reading that usage (but then I don’t hang out at more informal boards than the SDMB).

Isn’t the much more common usage to write ‘activity x is difficult?’ to express doubt on the statement ‘activity x is difficult.’?

Examples? Never seen this myself.

I think he meant for the respondent to say, “Activity X is difficult?”, rather than isn’t.

That certainly would make more sense. (In fact, my first post almost said only: “People use question marks this way?” but I thought it might be taken as a joke rather than a serious question.)

I’d say it’s just a normal use of a question mark:

Person A: X is true.
Person B: X is true? (Short for: Is X really true, or have you maybe not considered the situation fully?)

I am not a grammar expert, but would it be an inquisitive statement?

The usage you describe is incorrect. There is no question being asked. An ellipsis would be a possible way to end the sentence to indicate further thoughts.

“Activity X isn’t difficult…”

Isn’t it a rhetorical question?

Lots of sentence fragments can best be understood if the rest of the sentence is filled in.

Really? Yes.

That full sentence would be something like, “Do you really believe that?” or “Is that statement really true?”

So when you say “Activity X is/isn’t difficult?” the full sentence is more like, “Do you really believe that activity X is/isn’t difficult?”

Ellipsis. The linguistic ellipsis is not exactly the same as the … ellispis but both have their origin in missing words.

Pretty sure the OP said “isn’t” on purpose. The example is of someone outright refuting the original premise but conveying a sense of doubt by using the question mark. It is clearly not a question, rhetorical or otherwise.

I don’t see how it isn’t a question. That sense of doubt is itself a question. It’s like adding “right?” to the end of a sentence.

And I’d also say that the usage is ungrammatical: the proper way of expressing doubt is with a question mark in parentheses.

If that’s the case, then the name is ‘confusion about punctuation.’ I’ve seen this usage as well and always mentally replace the question mark with an ellipsis and a confused smiley, personally.

“X is difficult”
“X isn’t difficult? [refutation]”

I’ve never seen this, but could the actual quote be “What the heck, X isn’t difficult?”. Since what the heck is a question, maybe they mistakenly used the question mark.

But like I said, I’ve never seen this?

I have seen (rather, I’ve heard) this construction used on occasion. By Aussies in my gaming guild. It’s definitely not what I would say is normal or common, at least in the US.

I believe there’s an implied “but” at the beginning of the sentence, and at the end is an implied “so why are you proposing this?” It’s just used to express incredulity that the proposed solution was ever even conceived of in the first place–it’s THAT unbelievable. The question mark in text probably denotes the upward inflection used when spoken, rather than the use of an actual inquisitive.

AFAIK there is no name for this construction.

Think it’s called a question.

When I’ve seen it used it seems to be a snarky way of saying “you’re full of shit.”

Maybe they’re sort of using the question mark to represent a high rising terminal, or uptalk, or something along those lines.

Alternatively, it’s short for something like "(Um, are you really unaware that) activity X isn’t difficult?

I tend to use it to indicate my own uncertainty in my refutation.

So rather than: “I’m not sure but I seem to recall that position x does not apply in Alabama, does anyone else have that same recollection or am I missing something here?”

It’d be: “Position x is pretty usual in Alabama?”

It’s like a lot of internet behaviour - a lazy way to get a point across when you’re posting a quick reply.

First I just want to make sure I am not confused here. Do we all agree that in general, statements with a question mark are not strange? It is just using a question mark where no question seems to be intended, right?

I would just think they mixed up two sentences each saying the same thing in a different way:

“Activity X isn’t difficult” X is not difficult, so your premise is invalid.
“Activity X is difficult?” You think X is difficult? It isn’t so your premise is invalid.

Mix the two up in your head and you get “Activity X isn’t difficult?”

Could that explain it?

Yes, I used the “isn’t” on purpose. I think Exapno’s pointer to the linguistic ellipsis is on the mark.