Is the main theme in King Lear filial ingratitude?
Filial ingratitude is related to the dominant theme of the play, but in itself is not the play's central theme. Lear's relationship with each of his daughters serves to dramatize the concern and conflict that drives the play - the obligations and definitive nature of social roles.
When Lear abdicates his throne and breaks up the kingdom, he is acting against nature. It is the nature of power and kingship to be the steward of power (that is, to keep it as long as possible). Lear's relationship with his daughters, uniform at the play's outset, is defined by his kingship within the family.
He is the ruler, the authority, the "owner" of the land. His daughters and his subjects abide in his kingdom according to his wishes. When Lear announces that he wishes to take of the crown, he is attempting to reverse the natural order that existed (for himself, for his family, and for his country).
This attempted reversal is evidence of a (literally) epic hubris, where his pride leads to an unveiling of the forces of nature that will either correct Lear's behavior or destroy him to restore the "natural order".
Lear's downfall is the result of a tragic flaw in his character: his majestic sense of himself is not bounded by the norms of the natural order.
Lear's daughter's play a part in the corruption of the natural order, demonstrating a will to disrespect their father; to manipulate and deny him. ("Goneril treats Lear severely and appears quite monstrous.")
Yet, their part in Lear's tragedy is not descriptive of the larger tragedy he suffers, a crisis of identity, morality, and perspective wrought by forces outside of his family.
...the harm that Lear suffers at the hands of his older daughters, the reduction of his stature, is far surpassed by the cataclysmic destruction that the king calls down upon himself.
Filial ingratitude is a dominant theme in King Lear. It is a universal theme in the sense that it is common to find many sons and daughters who show much ingratitude and cruelty towards their parents. In the play, there are two fathers (Lear and Gloucester) who suffer because of favoring certain kids to others. Their tragedy is caused by those whom they have already favored and preferred. The play gives us incidents which connect one father (King Lear) with his two ungrateful daughters (Goneril and Regan) on one hand, and another father (the Earl of Gloucester) with his son (Edmund). Those two lines of relationships display the issue of ingratitude on a very deep and comprehensive level.
What made this play a tragedy was the evil children's "filial ingratitude," for the "blindness" of Lear and the Earl was so great that only through suffering from the "monster ingratitude" of Goneril, Regan, and Edmund did they learn to distinguish the good children from the evil ones. It was "filial ingratitude" which opened Lear's eyes to the "painful truth": he had disinherited his good daughter and had given power to his evil daughters.
Lear expresses his great shock addressing ingratitude as an enemy that has occupied the heart of his daughter. He says:
"Ingratitude, though marble-hearted fiend,
More hidcous when thou showe'st thee in a child
Than the sea-monster!"
The traditional values that make the parent-child relationship natural and wholesome are distorted and destroyed in this play. The order and harmony that usually characterize a stable family are disrupted by the evil designs of the greedy Edmund, Goneril, and Regan. Lear and Gloucester are both trusting fathers. They foolishly believe the words of their evil children and banish the offspring that truly love them. As a result of their lack of judgement, both fathers are made poor by their unthankful children. The filial greed and ingratitude shown by Edmund, Regan, and Goneril bring immense suffering to all.
The play begins by an unusual incident. King Lear wants to divide his kingdom among his three daughters because he has become too old to rule. Therefore, he asks each one to express her love to him. The first two daughters (Goneril and Regan) choose very passionate and poetic terms to flatter their father which reflect how hypocritic they are. Goneril says:
"Sir. I love you more than words can wield the matter;
Dearer than eyesight, space, and liberty;
Beyond what can be valued, rich or rare;
No less than life, with grace, health, beauty, honour."
The most horrible moment occurs when it is Cordelia's turn to speak. Lear is shocked when Cordelia has not said what he expects from her as his most beloved and dearest child. She says that she loves him as any dutiful daughter should love her father:
"…I love your majesty
According to my bond; nor more nor less…
You have begot me, bred me; I
Return those duties back as are right fit