Ad De-Lo Yada

There's a dispute amongst the later commentaries regarding the obligation to become intoxicated on Purim until one can no longer distinguish between 'Blessed be Mordechai' and 'Cursed be Haman' - whether one must get up to the point where he doesn't know the difference, but not cross over into a realm where good and evil are blurred, or whether one must go beyond that limit to where he actually can't distinguish good and evil.

Here's how I explain the 2 positions (the short version):
The first position starts with a relatively bright person, intellectually sophisticated, and, by habit, non-judgemental. He sees most things in shades of gray. He probably went to Gush.
Granted, there's much value in refraining from making value-judgements and remaining non-commital and neutral, but if it becomes a value on its own then there's a danger of complete dispassion and inability to distinguish right from wrong. Take the Democratic Party, for example. I think that Bush won (both times) not because people necessarily agree with his definitions of good and evil, but because he's willing to label something as good or evil in the first place. There's a danger in going too far with that as well, so balance, as usual, is the order of the day.
Thus, one day a year, we are enjoined to erase the gray areas and force them into identifying as balck or white. Are you with us or against us? Are you Israel or Amalek? In this model, by abandoning the rational, we are able to see good and evil for what they are and thus make real value judgements. That's not to say that I need to run around making those value judgements the other 353 days a year; it's ok to be a Gushie on most days. But on Purim we all need to be Frumteens moderators. Nothing gray. Just all black or white.

The second position would then advocate that one must even go beyond that and enter into a world of perception where there's no distinction between good and evil. Coincidentally, Nietzsche wrote a book called 'Beyond Good and Evil' in which he argues that one may achieve a degree of authenticity where one must, perforce, act out that which is criving him and not pay attention to conventional categories of good and evil. Self-actualization is the over-arching rule of the ubermensch. Good vs. Evil gives way to real vs. fake. This distinction has become a linchpin of modern phsychology and philosophy, generally overused by the likes of Michel Focault to pretty much encourage every whim or fancy out there. Very few have actually transcended the categories of good and evil; most who claim to are in fact regressing to an infantile non-disctinction of good and evil, which can't really distinguish between the real and the fake either. But I digress.
In the Ishbitzer school of Chasidus, the category of 'aveirah lishmah' is invoked to describe this category of beyond-good-and-evil. Once one acheives a state of consciousness where all is perceived as pure manifestation of God, one no longer experiences himself as an autonomous being, rather as a being of pure, instinctive 'retzon Hashem'. It perceives even Haman as 'retzon Hashem'. The goal of this type of intoxication is to temporarily experience this going-beyond-good-and-evil. Of course if one is unsure that deep-down he's unmotivated by retzon Hashem (like in a Freudian model - but unmitigated rezon Hashem serves as the 'id'), then it's probably not a good idea to go there. I know I won't.

I think that both opinions are great. Eilu ve-Eilu, and whether one minimizes or maximizes, one should remember to focus his thought toward the Heavens.