Booth, Stephen. "Macbeth, Aristotle, Definition, and Tragedy."
King Lear, Macbeth, Indefinition, and Tragedy. New Haven: Yale UP, 1983. 79-118.

Thesis: Booth's article is not really about Macbeth. It's his attempt to redefine dramatic tragedy, using Macbeth as a convenient example.

Booth first attacks Aristotle's famous definition of tragedy. He has various complaints about it, but his most fundamental one is simply that it is a theoretical definition; Booth says, "Theories of the nature of tragedy . . . keep us from facing tragedy itself" (84).

Booth's own definition of tragedy is paradoxical, because in defining it he first asserts that it cannot be defined. He says that in real life, outside of the theater, "tragedy . . . is a category for things that should not have happened but can be neither remedied nor filed away under 'things to be been expected under the given conditions'" (84). He continues:

We use the word tragedy when we are confronted with a sudden invasion of our finite consciousness by the fact infinite possibility—when our minds are sites for a domestic collision of the understanding and the fact of infinity. Tragedy is the word by which the mind designates (and thus in part denies) its helplessness before a concrete, particular, and thus undeniable demonstration of the limits of human understanding.   (85)
As for tragedy in the theatre, Booth regards it as one great big contradiction in terms, an attempt to make understandable that which is beyond understanding: "the plays we call tragedies are . . . benign (though futile) efforts to deny the existence of tragedy" (85).

In the second part of his essay Booth uses a discussion of Macbeth to illustrate his points about real-life tragedy and theatrical tragedy. His writes that while the events depicted in Macbeth are tragic, the play is—like all theatrical tragedies—an inadequate container for those events. The play, according to Booth, has a neat beginning, middle, and end, but the events of the play are such that "Macbeth is all middle." Here's an example of how he argues this point:

     The inconclusiveness coeval with the close of the action and the end of the play is—to the dismay of generations of actors and critics—actually demonstrated on the stage.
     Macbeth speaks his last line, "Lay on, Macduff / And damned be him that first cries, 'Hold, enough!'" (V.viii.33-34). The sentence asserts continuation. But its occasion bespeaks finality: Macbeth is trying "the last"; this is a fight to the death. The couplet rhyme bespeaks finality too. The immediately ensuing action is simultaneously complete (Exeunt—the scene is over) and incomplete (Macbeth and Macduff go off fighting, and we hear the fight continuing off-stage.) Then the completed scene continues. Macduff drives Macbeth right back out on the stage again and kills him. (92)
Furthermore, according to Booth, there's no sense of finality even when Macbeth is killed, because he doesn't have a death speech, and because the audience might be able see that the actor is still breathing.

Bottom Line: Booth has such a low opinion of tragedy that you wonder why he even bothers.