A: Logically impossible (Mahaale Aqli) is something the occurrence of which seems improbable to reason or logic; in other words which is impossible by itself; for example having controversies such as associating anything or anyone with Allah, which is absolutely ruled out by reason and common sense does not admit its happening or for example the statement that the universe is contained in the shell of an egg (unless the world becomes small and the egg large). Obviously such matters are logically impossible.
As for the commonly impossible; they are things which can happen by themselves, that is, logic or reason does not rule out its possibility; but which are not likely to happen in the normal course. They include conception of a fetus without a father as in case of Isa (a.s.).
Miracles shown by all divine messengers are also as such. They are against ordinary but not against logic. For example: speaking and movement of animals, trees and stones etc; so also curing of born blinds without medicine and even ma k ing the dead alive. All these are abnormal phenomena, but the Almighty Allah makes them possible through the hands of His Messengers for verification of their prophethood or Imamate. None of such events are against logic and reason does not rule out their occurrence.
Sayyid Abdul Husayn Dastghaib