Goldberg, Jonathan. "Speculations: Macbeth and source."
Shakespeare Reproduced: The text in history and ideology. Ed. Jean E. Howard and Marion F. O'Connor. New York: Methuen, 1987. 242-264.

Thesis: Here's the first paragraph:

This paper (or so its title suggests) poses a plurality of speculations against a presumed singleness of source; it glances, thereby, at a dispersal of origins. Source — in its heterogeneity — is its concern, aimed ultimately at locating Shakespeare's relation to Macbeth. But, it can be assumed, there is no immediate path to the author as source of the text except through a relay of mediations, and, by the end, even the supposed ultimate source — the author — must be considered within a heterogeneous dispersal.  (242)
Here's the last paragraph:
Confronting source — and end — the play registers an excess, unsettling in its indifferent and repetitious production, one king after another, a Malcolm for a Macbeth, raised on the body of woman, embodied in the text. The partnership of indifference begins (and ends) in rivalry over the letter, or Banquo's confrontations with the witches:
                   You seem to understand me,
By each at once her choppy finger laying
Upon her skinny lips: you should be women,
And yet your beards forbid me to interpret
That you are so.                            (I.iii.43-7)
Their beards and fingers on their lips forbid interpretation and point beyond an order of words and utterance to an excess at the source. Generators of the text, they suggest that the male fantasy of Macbeth may have as its counterpart the fantasy of the autonomy of the artistic imagination — Prospero's fantasy in The Tempest, for instance, when he displays his power in a masque whose deities are all female — and they caution the critic who would describe the play as the free workings of a mind playing with its sources. At the furthest reach of speculation, they intimate that the mirrors in Macbeth represent a meeting of authority and author swallowed in its source. That textual situation might be named Volumnia.  (260)
I didn't understand these two paragraphs, or anything in between, but I was heartened to speculate that as the deconstructionist game is played, it's very possible that Goldberg doesn't understand what he's written either.

Bottom Line: Radical deconstructionism.