I was reading a bit on necromancy and considering how magic was understood as acts of summoning. Rather than the practitioner directly using powers, they were relying on demons to use their powers to do the practitioner's bidding. This raised a lot of questions for me, especially considering alleged books of magic are usually suspected to have been written by priests.
Did the Church believe during this time that God could be petitioned to intervene in human affairs, or that the saints or angels could mediate or provide protection? If so, how did the Church distinguish petitionins for demonic magic from petitions for miracles, or would they not have even been asking this question? Were such distinctions primarily politically motivated? Were there any concerns that so much power being ascribed to the devil/evil would cause a sort of lapse into ditheism?
Hope the through-line with these questions makes as much sense to others as me.
In short answer, medieval theologians seemed to regard apparent miracles performed by demons as not "true" miracles, since their quality are limited compared to those by the God, only one who can do anything outside the order of the whole of creation (that is the narrow definition of the "true" miracle).
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The following is quotes from Pars I of Thomas Aquinas' Summa Theologica (Question 110, Article 4):
"Reply to objection 2: As has been explained, miracles occur, simply speaking, when something is done outside the order of the whole of created nature. But since not every power in created nature is known to us, when something is done outside the order of created nature as it is known to us and through a created power that is unknown to us, then there is a miracle as far as we are concerned (miraculum quoad nos). So, then, when demons do something by their own natural power, these are not called miracles simply speaking, but are instead called miracles as far as we are concerned. This is the sense in which magicians work miracles through demons.
These miracles are said to be worked “through private contracts” because every created power in the universe is like the power of a private person in a city. Hence, when a magician does something through a pact entered into with a demon, the deed is done, as it were, through a sort of private contract.
By contrast, God’s justice is to the whole universe what public law is to a city, and so insofar as good Christians are said to work miracles through God’s justice, they are said to work the miracles “through public justice.” (Translation is taken from: New English Translation of ST online)
Thomas comments further in Question 114, Article 4 in the same Pars I:
"I respond: As is clear from what was said above (q. 110, a. 4), if ‘miracle’ is taken in the proper sense, then neither demons nor any other creature can work miracles—only God can, since a miracle, properly speaking, is something done outside the entire order of created nature, and every power belonging to a creature is contained within that order.
"However, ‘miracle’ is sometimes used in a broad sense for something that exceeds human power and understanding. And given this sense, demons can perform ‘miracles’, i.e., works that astonish men insofar as they exceed their power and understanding. For even a man, to the extent that he does something that lies beyond the power and understanding of another man, inspires in that other man admiration at what he does, so that it seems that in some sense a miracle has been performed. Notice, however, that even though demonic works of this sort, which seem like miracles to us, do not satisfy the true notion of a miracle, they are nonetheless real entities in certain cases. For instance, through the power of demons the Pharaoh’s magicians made genuine snakes and frogs (Exodus 7:12 and 8:7)......." (Translation is taken from: New English Translation of ST online).
NB: bold in both quotes is added by me.
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It is also worth noting that the alleged hypothesis (stated above in OP) on how necromancy worked was not the only explanation of how magic worked in the Middle Ages. To give en example, William of Auvergne (d. 1249), elder colleague of Thomas in the university of Paris, distinguishes magi those who practice natural magic and thus are harmless from malefici, users of evil magic like necromancers (Lawrence-Mathers & Escobar-Vargas eds. 2014: 77).
William comments on the natural magic that:
"The third type of error is caused by a certain marvellous phenomena. These are in reality works of nature, but because their natural elements, or their combination, or mixing, or some other aspects, appear to be produced by deliberate intervention, they are believed by the ignorant to be the work of deons. And natural magic, which some philosophers call necromancy or false philosophy (philosophica), is concerned with such works. these terms wonders of this science, which are the result of powers imbued in nature by the creator, are believed by ignorant men to be the work of demons.......Through this error they inflict a double injury upon the creator: firstly by denying that the power of demons depends upon the will of that same creator; and secondly by denying the truth of nature (Lawrence-Mathers & Escobar-Vargas eds. 2014: 124, doc. 29)."
It is true that scholars sometimes had difficulty in distinguishing which kind of magic should primarily regarded as "natural" one from which must be the work of demons, however (Kieckhefer 1989: 182-85).
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