"Absurdity is the most obvious theme explored in Absurdism. Absurdity characterizes a world that no longer makes sense to its inhabitants, in which rational decisions are impossible and all action is meaningless and futile."
Lear goes crazy because his world is turned upside down by his inability to believe that his two daughters, Regan and Goneril, do not love him, will not shelter him, after he has given away his kingdom.
The fool, has more awarness and good sense and ability to see, than the King. The fool knows that Lear has made a terrible mistake putting his faith in his daughters to take care of him. He chides King Lear for giving his house away. The fool recognizes that the two daughters don't care about their father.
"Lear. What canst tell, boy?
Fool. She will taste as like this as a crab does
to a crab. Thou canst tell why one's nose stands
i' the middle on's face?
Fool. Why, to keep one's eyes of either side's
nose, that what a man cannot smell out, he may
Lear. I did her wrong,—
Fool. Canst tell how an oyster makes his
Fool. Nor I neither; but I can tell why a snail
has a house.
Fool. Why, to put his head in; not to give it
away to his daughters, and leave his horns with-
out a case." (Act I, Scene V)