I'm writing my paper on the use of humor in Dostoevsky, and as part of the research process I'm reading Jokes and Their Relation to the Unconscious by Freud. I found this great part about nonsense and absurdity being liberating. For Freud, children find it pleasurable to combine all sorts of random words together to form an absurdist word-salad, but as they get older, their parents scold them and they start to weed out the sentences that are deemed as "nonsensical". Freud therefore sees adult nonsense and freedom of unrestricted thought as liberating because of how restricted it is by societal norms.
Furthermore, Freud sees alcohol as being liberating when one is in a cheerful mood, because it "reduces the inhibiting forces... and makes accessible once again sources of pleasure which were under the weight of suppression... Under the influence of alcohol the grown man once more becomes a child, who finds pleasure in having the course of his thoughts freely at his disposal without paying regard to the compulsion of logic."
I see characters like Myshkin and Alyosha and Zosima and children as capable of evoking an innocently 'silly' effect. Some of their interactions are pleasurable for the reader to witness because they are simultaneously of the utmost gravity and lightheartedness and are unabashed by seeming nonsensical. They also love very readily, and are even beautifully nonsensical in their love (think of Alyosha and Krasotkin's silly and endearing love declarations). Characters like these don't drink much, because they don't need alcohol in order to reduce their inhibition.
On the other hand, buffoonish characters like Fyodor Pavlovich and Ilyusha's father and Marmeladov are way more inane than they are serious and also are constantly wasted. These characters also fall in love fairly readily, although it is decidedly more sensual than the former characters.
And sarcastic characters like Ivan and Rogozhin typically don't drink much, but not because of the reasons that 'silly' characters don't. They seem to feel as though they don't need to--or cannot-- reduce their inhibitions. They are constantly thinking and processing and getting in their own heads and they don't fall in love very easily or often. Interestingly, they tend to come to non-alcohol induced delirium of their own accord.
Once again it seems that child-like and innocent characters win in their uncanny ability to be uninhibited and down-to-earth, and love. They strike a perfect balance between the heavenly and the earthly. They're so perfect that you'd think they'd read all the self-help books on the shelf (I guess that's kinda what the bible is...)