From Nevill Coghill and C.S. Lewis I learn of four levels of allegory as described in medieval times; which I understand as follows (and this is my made-up shorthand terminology).
1. Primary. The literal level of what is described.
2. Referent. That secondary literal meaning which is encoded in the first level.
3. Moral. Any underlying moral point or message.
4. Ultimate. The ultimate level of understanding the human condition - usually spiritual or religious, but perhaps some other non-religious ultimate.
(In what follows, I am blurring the difference between allegory and symbolism, in order to emphasize the layering. Often the allegorical interpretation is optional, subordinate or may be denied by the author. Strictly, though, the allegorical layers ought to be deliberately and consciously encoded in the text - as William Langland did with Piers Plowman.)
So that Animal Farm by George Orwell has the primary literal level of being a story about animal and farmers, a referent literal level of being about the Russian Revolution, and a moral level of being about the tendency for revolutionary ideals to be corrupted. It does not have a substantive Ultimate level (at least, it does not for me).
Another, fuller, example might be Robert Frost's poem Nothing Gold Can Stay:
Nature's first green is gold,
Her hardest hue to hold.
Her early leaf's a flower;
But only so an hour.
Then leaf subsides to leaf.
So Eden sank to grief,
So dawn goes down to day.
Nothing gold can stay.
1. A poem about leaves.
2. Referring to Life in General ('dawn goes down to day')
3. Moral. A poem about the evanescence of beauty ('hardest hue to hold') it should be cherished while it lasts.
4. Ultimate. That this is the Christian human condition ('Eden sank to grief')
The fourth 'ultimate' level of religious meaning may be implicit: a matter of 'pointing offstage', as throughout The Lord of the Rings.
Or it may be depicted partially but inexplicitly - as in the Harry Potter series with its ghosts, talk of souls, the 'Veil' (dividing death from life) in the Ministry of Magic, and the King's Cross limbo' chapter of the last book.
Or there may be an explicit description and explanation of the Ultimate level, as with the last of the Narnia Chronicles.
The Death Eaters in Harry Potter are an obvious three level allegory of Nazis - with Muggle hating representing anti-Semitism in a literal fashion, and the third layer of an egalitarian morality of tolerance also very obvious.
What makes the Potter series so much richer than this is that the fourth and ultimate moral layer is Christian, supernaturalist, traditional; with multiple allegorical pointings to the Christian story, with its sacrificial theme, death and rebith etc, and moral principles (esepcially the centrality of Love in the sense of 'Charity' or Agape).
So that Death Eaters are ultimately evil not because they inflict pain on others (Harry does that), or because they are snobs; but because/ insofar as they reject Love and worship Voldemort, who is a false god.
And what of Political Correctness?
Clearly much PC art can be interpreted as having the first three levels of allegory - but not many PC works go so far as to provide an Ultimate level of allegory.
The ultimate level for political correctness, as I have argued in this blog passim - is a this-worldly perspective of human life as regulated by abstract rules that are 'inverted' - i.e. non-spontaneous, non-natural, and with a utilitarian justification (i.e. optimizing happiness for the greatest number - but especially minimizing suffering).
PC allegory might also has characteristic themes such as diversity/ multi-culturalism, egalitarianism, peace and so on.
The best example that comes to mind of a PC work of art which depicts the Ultimate level of allegory - the 'sprituality' of PC - is the recent movie Toy Story 3 which I reviewed last year:
Of course Toy Story 3 has the first three levels of allegory since it is
1. Literally about toys,
2. Referring to humans - each toy being a recognizable human type,
3. Has a moral message/s concerning the importance of friendship, courage and loyalty (i.e. the pagan virtues of Natural Law) - and also PC themes of egalitarianism (all toys equally deserve equal gratification, hierarchical command is characteristic of evil), diversity (inclusive of all types of toy), anti-cruelty (evil toys are cruel, good toys are non-violent) etc.
But in addition the resolution of Toy Story 3 strikes me as a depiction of a kind of paradise of political correctness.
The toys voluntarily choose to accept an egalitarian, multi-cultural and diverse life (inclusive of all the different toys of different types) - by sharing equally both pleasures and duties, and accepting that it is all going to end in destruction; yet accepting destruction as the essence of life: sweetened by friendship.
The ideal life as a kindly mutual huddling against the indifference of the universe.
I see the denouement of Toy Story 3 as being an acceptance of the ultimate PC reality of life as governed by abstract rules - rules whose face value is utilitarian - but in a world where utilitarianism (a life of gratification equally and for all) lacks further validation.
It also has the ides that 'meaning' comes wholly from relationships, despite that relationships are inevitably short-lived.
It is a tragic ultimate view of life, a fusion of pagan and PC, beautifully done. But having seen this ultimate and participated imaginatively in it, the deep current of hopelessness in modern life is entirely understandable.