What's the derivative of your PGF?

"They're a good person." This phrase drives me insane. Have you ever heard it used to actually describe someone that does good? Maybe, but much more often it's used to justify a lack of good, to overlook someone's vices. How often do you hear something like, "He may cheat on his girlfriends once in a while, but he's a good person." or "She may stew in envy and bitterness toward her sister, but she's a good person." I propose that this phrase is a deeply flawed and destructive one.
I think the inherent drawback of this phrase is that it is binary. What one is really trying to say, generally, is that so-and-so is not a bad person. The underlying assumption is that people are either good or bad. It's the reinforcement of this idea that may be the most destructive part of this phrase. Good and bad are like and hot and cold. Water may be cold, but not cold enough to drink. Water may be hot, but not hot enough to shower in. We need to stop thinking of this, and many things, as having a dividing line, but rather as a spectrum. Goodness is closeness to perfection, while badness is farther away, or closer to pure wickedness and evil.
All that said, let's cast this in some of the precise terms that I really understand. Let's say that good and evil are like a number line, there's infinity on one side (infinite goodness) and infinity on the other (infinite evil). The number picked on this line defines how good a person you are. Don't take this opportunity to say that anyone with a goodness value below x (typically zero-using negative values to denote evil and positive values to denote goodness), because this is arbitrary. More importantly, let's say that someone's goodness value is defined at any point in time by some function, which I'd like to call one's personal goodness function-or PGF. I think that likely the most important aspect of a person is not the instantaneous value of the PGF, but rather the derivative (or rate of change for you non-mathematicians out there). One who is improving by leaps and bounds, growing, learning to do good and ceasing to do evil I declare is much more worthy of praise than one who may do a great deal of good but is slowly letting wickedness, darkness, hatred, and whatever else you wish to use to describe evil fester in his/her heart and turn him/her into a force for darkness.
The derivative of the PGF also tells us with what zeal one is improving oneself. If someone is slowly growing and becoming better, good for them. If one has such a commitment to overcoming vices and developing virtues that every second seems to teach them how better to perfect themselves, so much the better.
It is by being content with ourselves that we fall into bad habits. It is by letting little flaws live peacefully within us that we learn to ignore the good things we could be doing. Only be commitment to improving, perfecting ourselves can we learn to do all that we need to for the world's problems of greed, hatred, lust, and pride to be overcome. One way we can do this is to constantly ask yourself, "What's the derivative of your PGF?"