One of his principle themes, which might be summarized "Truth is what those in power say it is", may, as the writer says, appear as a truism to some, but it is something that deserves to be taken much more seriously than it is. Ask youself, for example, why do you believe that Timothy McVeigh was responsible for the OKC bombing? Do you know the crucial pieces of evidence* which resulted in the determination of his guilt, or do you just take the word of the government and the media. We need a lot less such uncritical acceptance and a lot more skepticism in such matters.
*It is my claim that what was presented at the trial falls far short of providing "proof beyond a reasonable doubt".
What're you, a communist . . . a traitor . . . a rag-head lover . . . worse yet, a liberdopian?
You should trust FBI, CIA, NSA, ATF, DEA, IRS, EPA, the media and GW 100% -- they're only there to help you.
But why do you uncritically accept that these are the matters you should be interested in?
Of course, that is really only an academic point (pun intended) since:
A) McVeigh admitted it.
B) He's beyond reviving at this point.
This is the type of word-play that gives deconstructionism and other pseudo-philosophies the bad name they deserve.
Because something is widely believed does not make it "true."
And calling it "truth" does not make it "truth."
Remember the old joke: If you call a tail a leg, how many legs does a horse have?
Answer: Four, because calling a tail a leg does not make it a leg!
Take your hypothetical. If we grant your premise that the government manages to convince a large number of people that a "lie" is "true," it is stll a lie or a falsehood.
It is just a widely-believed falsehood. It is not magically promoted to truth, by the number of people who believe it.
(Granted, in everyday life we tend to take what is widely believed as the "truth.")
One evaluates any empirical claim by the evidence for and against it.
Unfortunately, how many people believe something (a "democratic" epistemology) is a poor guide to its truthfulness.
To conflate "truth" with what is widely believed only adds confusion, not clarity to the process/argumemt.