Against what criticisms does Addison defend Milton's epic? How does Addison enlist neo-Aristotelian ideas on the dramatic unities in the service of his argument?

Addison in the first installment of his essay on Milton's Paradise Lost clearly states his goal of defending Paradise Lost from the criticism that 'whether Milton's 'Paradise Lost may be called an heroic poem' although some critics prefer to all to call it a 'divine poem'.To defend it as a successful English epic, Addison judges it by the neo-Aristotelian ideas on the dramatic unities set down by La Bossi in Traite du poeme epique, Horace in his Ars poetica and standards of Homer and Virgil, two great epic poets.

Addison first focuses on the 'fable' or plot of an epic poem. According to neo-Aristotelian idea on the dramatic unities, a perfect plot should possess three qualities of its action - Its singleness, completeness and greatness. He refers to Horace,Homer and virgil open their actions in the middle of the story and the preceding events are described by characters by way of episodes. Milton closely imitates these two great poets and opens his paradise lost with an infernal council plotting the fall of man.He describes the preceding events later by way of episode.  Referring to Aristoile Addison also detends the episodes in paradise Lost that arise naturally from the subject and they are filled with exciting incidents that give the pleasure of the greatest variety and simplicity. Like Virgil. Milton deals with such great action like the Fall of Man. The episodes or digressions run parallel with the great action of the poem and enhance the dramatic unity of the plot like the subplots of Dryden's tragicomedy as they have close affinity with the principal subject.Addison enlists the second qualification of the action of an epic  poem  and says that it should be complete. Neo-Aristotelian ideas suggest that a complete action consists of a beginning,middle and an  end. Nothing should go before, after or in between it. The action should be just, regular and interconnected and no single step can be omitted from the beginning to the end. Just as in Homer's iliad and virgil's Aeneid, the parts of Paradise Lost are described in the most distinct manner, and grow out of one another in the almost natural method. Milton is superior to other epic poet in regard to the compactness of his plot. The third quality that Addison enumerates is the greatness of action to maintain the dramatic unity of an epic poem. The greatness suggests not only the seriousness of subject but also the due length of an epic poem. Milton's Paradise Lost deals and determines the fate f the entire human species. The action of a plot should not be too long to befall our memory or too small to meet the need of a great poem. Although Milton had less freedom and had to be very cautious expanding and diversifying the plot with episodes that do not offend the religion of the country, Milton had successfully filled his plot with many surprising incidents that bear close analogy with the holy Writ and maintain the essential unity of the plot. Besides, there is an unquestionable magnificence in every part of Paradise Lost which is much greater than those of The iliad and The Aeneid.Addison, in this way, lists the neo-Aristotelian ideas on dramatic unity to defend Milton's Paradise Lost as a successful epic poem.