While many of the villains found in the Batman franchise have backstories that explain their motivations for what they do, the one that stands out for having no such story is The Joker. On the surface, The Joker appears to be simply a psychopath. But, if we examine the character a little further, one must ask whether The Joker really is insane. There have been theories floating around for quite some time that claim that The Joker is not insane at all, but is actually “hyper-sane.” Hyper-sanity is basically the psychological theory that one who views the world as it truly is will, while also having a full realization of the self, will lead one to act in ways that most people would consider to be insane.
The Joker, although a fictional character, can make for an interesting psychological study. While he certainly possesses traits of both sociopathy and psychopathy, these traits due to the specific way in which he views the world. His mind has moved past any sort of dogmatic beliefs regarding morality and ethics, which are things that we, as humans, often use in order to help us to determine what actions we will or will not take. The Joker is actually correct in his stance that there are no actual ethical standards that exist objectively outside of the human mind and human preference, and he does not resist acting based upon this understanding. For this reason, we can conclude that The Joker is actually operating in a world without delusion or illusion, and so it is apparent that he may not actually be insane, but more sane than the rest of us.
One certainly does not have to condone the actions of the clown prince of crime in order to come to this understanding.