The literal sense of humour.

I was wondering today, when is it that humans laugh. After much deliberation, it seems to me, who is so bent upon finding a small finite number of underlying causes for all these great mysteries, that the great thread that connects all laughter is the absurd. I think most humour originates from a sense of the absurd, be it slapstick or witty. Or any of those other genres mentioned under humour in social networking forums. I do not have the patience to take each particular genre and iterate my case because its hard for me, honestly, to break it up into so many genres. I think its essentially of two fundamental types. Those that involve the mind's processed response,i.e., post-thought. And those that are spontaneous,i.e., purely as a consequence of sight, like in the case of slapstick. In these two very fundamental types, i shall cite quick examples. When a man falls, what makes us laugh? I think its the absurdity of a fallen man. Just as we laugh when we see icecream on a friend's nose. Its just the absurdity of the sight. As for thought processed humour, one can find plenty in novels in the humour genre. But here's an instance: In 'The Pickwick Papers', Samuel Weller is called to the witness box. This is the sort of chap who is always in good humour. The attorney on the plaintiff's side wishes to quickly unsettle the witness. So he glares at him. The plaintiff begins:
'Now, Mr. Weller,' said Serjeant Buzfuz.
'Now, sir,' replied Sam.

Just the sheer absurdity of his throwing in that totally redundant 'Now,sir' was so hilarious it literally had me rolling on the floor laughing. I can cite many more instances to those interested in thinking about this seriously and discussing with me.

The reason i wrote this post, however, is that i'm not completely certain. I have a strong case for absurdity. But i was initially revolving around 'loss of dignity', i.e., 'humiliation' though the latter seems much too strong a word for what i wish to convey. And there might be something else that is a far better connect that i might've entirely missed out. If any one who reads this post has some other well thought out answer, i would be DELIGHTED to hear it and may be even discuss it if we can. Thanks!