In Confessions, book 7 chapter XII, St. Augustine writes:

  1. If things are sovereignly good, they are incorruptible.
  2. If a thing is corruptable, it contains good.
  3. Evil is either an incorruptible substance or a corruptible substance.
  4. If evil in incorruptible, it's sovereignly good.
  5. If evil is corruptable, it contains good.

To my mind, in derivations 4 and 5 Augustine perceives implication in reverse order. That violates the laws of logic. Am I right?


a) $A → ¬B (if sovereignly good, they were incorruptible)

b) supposing ¬B, therefore ¬B → A (for either it should be an incorruptible substance, and so a chief good)

Here is a logical mistake, like: A → ¬B (if color is black, it's not green); ¬B → A (color is not green, therefore, it's black)


It seems to me that Augustine's argument must be rephrased differently.

The first part of the argument is aimed at establishing that:

whatsoever things are, are good.

This means : every substance must "partake" of the Good.

In particular, this is so for a corruptible substance, because corruption is deprivation of (some) good.

Now, the conclusion is straightforward: evil is not a substance, because if so it must be

either an incorruptible substance, that is to say, the highest goodness; or it would be a corruptible substance, which would not be corruptible unless it were good.

You can see:

  • Thank you for the answer. But antonym of the highest goodness is also incorruptible, isn't it?
    – user25503
    Feb 10 '17 at 9:49
  • @user25503 - "antonym of the highest goodness"... do you mean the "not good at all" ? If so, tes; if "corruption is deprivation of (some) good" and to be not good at all is "without any "portion" of good", then if something (substance, etc.) does not partake of the good at all, there is nothing that it can be deprived of, and thus it is incorruptible. Feb 10 '17 at 10:12
  • This theodicy contains one disadvantage: good and bad in this evidence can be swapped (like positive and negative numbers on axis).
    – user25503
    Feb 10 '17 at 10:20
  • 1
    Augustine "ivented" theodicy : "Augustine of Hippo was the first to develop the theodicy. He rejected the idea that evil exists in itself, instead regarding it as a corruption of goodness, caused by humanity's abuse of free will." Feb 10 '17 at 10:50
  • 2
    See also Augustine Ontology and Eudaimonism : "Natural evils are attributed to the partiality of our perspective, a perspective that is often the result of our myopic materialism and tendency to focus upon our own self-interest. [...] With respect to the moral evil which is the product of human agency, these are the culpable products of a will that has become attached to lower goods, treating them as if they were higher. Moral evil is, strictly speaking, not a thing, but only the will's turning away from God" Feb 10 '17 at 10:52

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