"A big IF..."
It might or might not be. If conception happened at 30minutes, say, and the pill was taken 36 hours later; there's not "IF" about it, you've got an abortion.
If conception is delayed 36 hours and the pill is taken 24hours after, then, yeah, conception gets prevented and there's no "IF".
My main problem is the fact that we're all flippantly bantering about "IF" with human lives in the balance. That's downright macabre.
http://www.all.org/article.php?id=10742