> I don't see how that is open to interpretations, I can see a few things the author might be trying to convey. The most interesting would probably be "[There

> I don't see how that is open to interpretations, I can see a few things the author might be trying to convey. The most interesting would probably be "[There are cases where t]here's no observable difference [...]". I think the alternative I suggested ("[...] produce a result while pretending not to.") is better supported as the authors probable intent (while being a stronger statement and correspondingly less likely to be accurate). In any case, pragmatics + charity should tell us someone wasn't asserting we can't tell the difference between a person saying "I can't" and a person saying "I won't", and if you can't figure out what else they might have meant the first thing to do is ask.