If we don't know what justice is, how can we even define injustice, let alone recognize it?
A sense of right and wrong and empathy, both intrinsic to man, will do a pretty decent job at that.
Besides, if what you say is true, why do so many people who have so much comfort and pleasures and privileges in their lives whine about every little detail? (Not saying everybody or even most people like this do that, but a lot of people do.)
Man is never satisfied, not with himself and certainly not with his surroundings. Some people have to vent their perceived imperfection and the injustice done to them by their surroundings.
How? Imagination bases itself off of the known.
There is always a situation in which someone wants to either imagine good or imagine evil. We simply imagine the negative of the situation we are in. We can imagine what it would be like if our privileges fell away, to go to a neutral state if you will, and even turn negative when we turn the positive privileges around and imagine an opposite of them.
I really don't see how that would be problematic to do.
Only if they recognize it as torture.
Do you think people would not recognize torture in its most mundane sense?
I think you're misunderstanding. I'm NOT talking about appreciation, I'm talking about existence. Good and bad are only categorizations our minds came up with to help define whether or not something is agreeable and helpful, either mutually or selfishly. Therefore, they are interdependent.
Looking at it in such an abstract way, I'd say I disagree we need a negative on the scale in order to decide what is helpful or not. Why not start at 0 being not helpful at all and going up to being more and more helpful? Of course some things will be destructive, so a negative will eventually arrive in some situations, but I don't see why we would need a negative in order to measure the good of the world.
Then again there is a larger gap between -10 and +20, then there is between 0 and +20. But would you argue that difference between good and bad, in size, makes us significantly more appreciative of good?
As an addendum, I kinda feel like I should point out that this isn't in defense of any sort of God-concept.
That's good, not that I was really worried about that, but it would make this discussion far less interesting.