I understand the idea of a Virtue having a "moral opposite." That moral opposite being a Vice.
All I'm saying is that the opposite of a specific sin is not always a virtue and vice versa. Sometimes the opposite of a sin is simply not sinning (which doesn't always equate to being virtuous), and on rare occasions the opposite of a sin can be another sin, depending on how you define the opposite and how you define a sin.
I think you'd be better served simply choosing seven virtues that truly serve your lesson and not worry about slotting them into the arbitrary pigeonholes of being the polar opposites of the seven sins.
But I also understand these ideas.
I think that from a spiritual viewpoint it is a very interesting idea. Maybe it's just the mystic in me but I very much like the idea of one sin or vice being used against another. I think of that as being like spiritual guerilla warfare, where unorthodox tactics are used in an unpredictable way.
Now of course in the real world you'd want to employ sin against sin in a way that eventually leads towards the good, towards some benefit, and hopefully towards the development of a virtue. Then one sin, or vice, being employed actively against another would have a beneficial long-term effect.
And I also understand the point that the opposite of a sin might just be to eradicate the sin. That lack of sin does not necessarily equate to virtue. Saints for instance are known for their Virtue, that is they take their sins, seek to eradicate them and then specifically replace their previous Vices with Virtues. (I am not referring to the specific theological idea that all Christians are in-effect Saints, but the idea that certain Christians specifically seek to become exemplars of radical or very powerful Virtues, hence, their Saintliness. That is some Saints go out of their way to sacrificially act the part of Saints. It's the difference between a guy who is a weekend athlete, and a guy who sets out to be a professional athlete. Both are athletes, but the degree of dedication definitely differs, as does usually and practically speaking the real degree of effectiveness.)
For instance, to use a mundane example, a smoker might just stop smoking, which prevents any further damage to his lungs. Which is a step in the right direction for the health of his repository systems. In one sense this is a virtue. Do no harm. But it does not actually improve his lungs, or reverse prior damage. Proper diet, aerobic exercise, other actions of that kind will, or in other words rebuilding and improving on his previous condition, that would be a true Virtue (Capital V), and benefit. Stopping smoking would be to cease doing active harm, and is the kind of virtue one gets from "lack of vice," but improving yourself for real benefit, that is more like a Virtue.
Then again in some instances certain acts may be either a virtue or a vice depending on the degree of application. Eating is a necessary function which is obviously good for you. In that sense it could be considered a virtue. Eating unhealthy things or eating all of the time and to excess (gluttony) is a vice, with obvious negative side-effects. Same act, different manifestations.
That being said then, as far as game situations go, I think there are a number of interesting ideas that the complex interplay between vice and virtue might engender. The idea of evil being used against evil, in an almost guerilla like fashion, to achieve some good. The idea of a plot demanding far more than just "eradication of the bad," but rather the intentional redress of prior harm, or the development of Virtues and benefits to replace vices or harm.
As I tell my children often, it is not enough merely to do away with bad behavior or bad habits, but rather one should replace bad habits with good habits or behavior, and then one is less tempted to engage in bad behavior when that is easy to do. And because people often tend to be creatures of habit it is therefore much easier to practice good behavior when you have habitually practiced Virtues, than it is when you practice bad habits, or no habit at all.
Or put another way, practice Virtue long enough and it becomes your natural habit. Just as if you practice Vice enough (and I mean real vices here, not small indiscretions) and that becomes a natural, or one might also say, unnaturally-natural habit. (Or naturally-unnatural habit, take your pick.)And I think that was what VP was saying. That in the sense of action virtues always have natural opposites, which are the opposite type of action.
Anyways, back to gaming (and personally I like and think gaming should be used not just to practice mental and imaginary skills and capabilities, but real and personal and psychological and spiritual ones as well) you might have a situation where it is far from satisfactory to just "kill the monster," you might need to replace the monster with something of true benefit.
And it might not achieve the ends of an adventure or mission to merely be the one to kill the monster, but maybe the vice of the monster is somehow transferred to the character, who then must also defeat the Vice and somehow conquer it with a Virtue. That is you kill the monster and his vices are transferred to you as a sort of "curse" which you then must break or destroy with a blessing, benefit, or virtue. You don't just kill the disease, but you effect a truly counter-acting cure.
Of course there is always the old "one monster fights another" scenario. In that respect I can see a case where a monster might even want to change, convert, or be cured of his "monstrousness" and is therefore asked to asset in the destruction of another, even worse monster as a sort of penance or proof of his sincerity and purpose.
Anywho I can see any number of ways that Virtues and Vices might be played out in interesting and even unorthodox ways in a game or story. But for now I gotta hit the hay. See ya.