As "justice" is of the intelligible world, any idea of justice to be even a contender for the definition of "justice" must be, at least, (logically) validated truth.

As long as there's Something Worth Fighting For(tm), the fists of fury will flow.

World peace, as in everyone gets along? That will never happen.
Sorry

I would say these two reasons:

People like Hitler.

And lastly, the undying belief that war is inevitable and the only solution to our problems. Everybody just seems to think it's ok to think that.

I love John Lennon's "War is over, if you want it."

..But as long as everybody thinks it's the solution and as long as there are people out there like Hitler world peace can not exist.

It's very saddening.

So you're saying that anything even in the realm of possibly being close to the definition of justice, must itself be true? How does that make sense when I originally said the definition varies?

Dumb question.. there will never be world peace. The only way we all can survive on this planet is with separated countries working in partnership with each other, and we don't always agree with one another's decisions. When I think of world peace I think of a dictator governing the actions of all humans preventing disagreements between different continents but as we all know that will never work.

Just drop it, we will kill each other until there are no more people left to kill, I mean the best policy that we have come up with is; "Be peaceful or else we will come and kill you".

Right there is what is considered peace between countries. Working as a partner - therefore they are not fighting. Having different opinions/decisions is normal among individuals yet doesn't go against the idea of being peaceful with one another. Each to his own.
Ex: If you don't like Mr. X because he's gay doesn't mean you can't accept him. Just live peacefully with him. Many do so already.
The concept of world peace - can be reached. But all those in charge (who not all are dictators) are preventing it for whatever reason which I personally deem as stupid and selfish.

The way you described it, is the way I'd like to see it. Partnership between all the countries, no fighting. No need for dictators like you said.

Your assumption that "justice" is subjective is false. Truth in the intelligible world can only be known through logic. Logic is not subjective.

I would say that justice is theoretically subjective, as is logic - in many cases, justice is decided on who has the power or strength. Mostly, it depends on your point of view. What may seem ike justice or logic to one person may be seen differently by another person with another point of view.

Who said that justice is logical? IT IS subjective, plain and simple. Everyone has their own idea of what is "right" and "wrong" thus it is impossible to have one solid definition.