At The Valve they're discussing whether post-colonial criticism "assumes its conclusions even before it begins."
The responses so far seem to amount to "yeah, so what?" But lots of interesting variants of that. Several, for instance, are making the valid point that this is what all criticism (and in fact all scholarship) does. There's also the point that:
imperialism in culture, then we clearly have no conclusions to begin
with. We simply have objects of study. I don’t think it’s a
controversial idea to be open to possible connections between a major
historical process and the art that emerged during that process.
As a worthwhile offshoot of this conversation, Andrew Seal discusses Said's reading of Austen, from a postcolonial perspective:
Said pointed out the Bertram family's Antigua plantation was a sort of
enabling fiction, sustaining the family's fortunes and thus making the
action of the novel possible in a very real way. Said focused in
particular on a casual exchange between Fanny Price and Sir Thomas
about the plantation, drawing some fairly broad conclusions. A number
of critics (and likely a number of readers) have taken issue with
Said's rough handling of Austen and with the implication that Austen
was just one more lackey of the slave trade and British imperial
oppression more generally.