Orthodox spirituality, at the very least, would have a hard time accepting the concept, practice, and language of the modern indulgence as being within the patristic tradition.
Just so that you are clear I am not distorting the thought of St. Cyprian to modern concepts:
"Therapius had rashly granted peace to him after an insufficient time and in headlong haste, before he had done full penance and before he had made satisfaction to the Lord God, against whom he had sinned. This matter disturbed us greatly, because it was a departure from the authority of our decree, in that peace was granted him before the full and lawful time of satisfaction." (Letter of St. Cyprian and 66 Bishops in Council to Fidus, Letters 64.1, AD 251/2)
As to other patristic tradition here, there is a complete continuum of western theology on this matter and with this language, from Tertullian through St. Cyprian to St. Ambrose and St. Augustine and on to Pope St. Gregory. This is not an invention of Scholasticism, but the tradition of the west from its commencement in the Latin prose of Tertullian. The examples I have given from St. Cyprian are not him acting alone, but him acting in concert with the Roman Church, and with all his brother Bishops in Africa, and in line with what Tertullian first described and then complained about in his later rigoristic heresy along with St. Hippolytus of Rome. There was nothing isolated about what was occurring.
St. Ambrose for example: "Just as those who pay money absolve a debt, nor are they free of the name of debtor until the whole amount, even to the last penny, is absolved by some kind of payment, so to compensation of love and other virtuous actions, or by some kind of satisfaction, the penalty of sin is removed." (Commentaries on the Gospel of St. Luke, 7.156, AD 389)
And Tertullian: "Repentance is the price which the Lord has set for the awarding of pardon. The compensation through repentance is what He proposes for the buying back of safety from punishment." (Repentance, 6.4, AD 203/4)
And again: "This second and single repentance then ... is not conducted before the conscience alone, but it is to be carried out by some external act. This act, which is usually expressed and spoken of by the Greek work, is exomologesis, by which we confess our sin to the Lord, not indeed as if He did not know of it, but because satisfaction is arrange by confess, of confession is born repentance, and by repentance is God appeased. Thus confession is a discipline for man's prostration and humiliation, enjoining a manner, even as regards dress and food, conductive to mercy ... Confession is all of this ... so that it may by temporal mortifications, I will not say frustrate, but rather expunge the eternal punishments. Therefore, while it abases a man, it raises him; while it covers him with squalor, the more does it cleanse him; while it condemns, it absolves. In so far as you do not spare yourself, the more, believe me, will God spare you!" (Repentance, 9.1-5, AD 203/4)
The more you read of Tertullian and St. Cyprian, the more you see that the entire edifice of western/Latin theology comes directly from them.
You certainly have a deeper knowledge of the Western fathers than I do, and you make a compelling case that the language to which I object has a long pedigree in the West, one that includes fathers that are revered in the Orthodox Church.
I wonder if this is analogous to the Orthodox approach to considering the physical sufferings and crucifixion of Christ. The Eastern fathers and our services (with whom I am most familiar), talk about Christ paying the debt on the Cross, and use juridical language -- but it is not the heavy emphasis, and it is only one of many ways in which they talk about Christ's redemptive work. It isn't that we reject completely language about debts and laws and punishments and so forth -- it is more that they seem to be treated as one aspect only, and an aspect that isn't heavily emphasized.
It does seem that in the process of formalization and codification, a certain kind of language came to dominate in the west, language that we instinctively recoil against in the context of how we perceive Catholicism to "work", even though sometimes there are similar words, in the context and balance of our own services, that we fully embrace.
What I don't know is when this dominance of juridical thinking happened in the West. Perhaps it was far earlier than I realize. I really don't have the intimate knowledge of the western fathers that would be required for me to answer that to my satisfaction.
I have gotten a bit intemperate on this thread, and that isn't particularly good for my state of mind and soul. So I'm going to apply a little akrevia to myself and bow out, since I'm not helping anyone at this point.
This has been a good discussion. I've had some misperceptions corrected, and have learned about a broader way of understanding indulgences in particular. Even though I still can't accept the concept, I won't embarrass myself again by stating that these are exclusively a part of the doctrine of purgatory.