I see no relevant difference between the two cases.
Isn't that the entire point? I see this as a mathematical version of the modus tollens/ponens point made elsewhere in this page.
The quote says,
could mathematicians afford to use this literary device? How would a reader be able to tell the difference in intent between what I have just written and the following superficially similar passage?
This seems to me to mean: the two cases are different; the first is appropriately handled by serious proof-by-contradiction, while the second is appropriately handled by irony. But readers may not be able to tell the difference, because the two texts are similar and irony is hard to identify reliably. So mathematicians should not use irony.
Whe...
Here's the new thread for posting quotes, with the usual rules: