Slavoj Žižek calls attention to and connects the following two passages in Kant:
A people should not inquire withany practical aim in view into the origin of the supreme authority to which it is subject; that is a subject ought not to rationalize for the sake of action about the origin of this authority, as a right that can still be called into question with regard to the obedience he owes to it....[this] sets forth an idea as a principle of practical reason: the principle that the presently existing legislative authority ought to be obeyed, whatever its origin. (6: 318-9 and the German).
For a people already subject to civil law these subtle reasonings are altogether pointless and, moreover, threaten a state with danger. It is futile to inquire into the historical documentation [Geschichtsurkunde] of the mechanism of government, that is, one cannot reach back to the time at which civil society began (for savages draw up no record of their submission to law; besides, we can already gather from the nature of uncivilized human beings that they were originally subjected to it by force). But it is punishible to undertake this inquiry with a view to possibly changing by force the constitution that now exists. For this transformation would have to take place by the people acting as a mob, not by legislation. (6:339-40 and the German [The parts in bold are omitted by Žižek (because he is focused on a slightly different question--ES.])
As Žižek notes, Kant legislates a philosophical taboo (recall here.) A people cannot call into question obedience to present (lawful) government. This is not the place to explore if Kant allows either exceptions to such obedience or if a government stops being lawful (say because its laws become at odds with itself (recall my recent posts on Smith and Emerson and Thoreau) or because it has no de facto authority (recall my posts on Hobbes, Hume, Smith) etc.), such that no obedience is warranted anymore. Moreover, I am also going to pretend as if the events of the French Revolution have nothing to do with this doctrine of Die Metaphysik der Sitten. Rather, Kant's taboo limits the possible philosophical role of history (as a form of inquiry) on practical grounds (if not plain raison d'État). For, history has to stop just where it gets interesting. Moreover, if history is not allowed to tell the origins of (any) us as a political unity, it cannot provide a genuine causal account of our unity and, thus, is incapable of offering full explanations. (It's only when one lowers one's expectation of what a proper causal account is that such history gets allowed back in.) The taboo is especially striking because it goes against the classical ideal that inquiry into politics is among the highest philosophical goods (I'll remain agnostic on what the correct reading of Aristotle is).
Kant's taboo helps us better understand the demise within philosophy (and history) of history as a genuine philosophical enterprise. This has caused a so-called Kuhn-Loss for philosophy: we are incapable of recognizing much of Xenophon, Polybius, Machiavelli, and, say, Hume's History, as properly philosophical, nor (as I noted recently in response to Hazony's book), the main narrative of The Hebrew Bible.
Now Kant's taboo has a history, of course. Žižek points at Pascal's "mystic basis" for law's authority, which cannot be grounded in justice because its historical origin is (nearly?) always usurpation or conquest of some sort (as Hume noted in "Of the Original Contract." This seems to be Kant's source at 6:339-40.) It is no surprise then that Pascal embraces a doctrine of (Platonic) noble lies to block such enquiry. Even good Hume expects noble lies to emerge:
And though the philosophical truth of any proposition by no means depends on its tendency to promote the interests of society; yet a man has but a bad grace, who delivers a theory, however true, which, he must confess, leads to a practice dangerous and pernicious. Why rake into those corners of nature, which spread a nuisance all around? Why dig up the pestilence from the pit, in which it is buried? The ingenuity of your researches may be admired; but your systems will be detested: And mankind will agree, if they cannot refute them, to sink them, at least, in eternal silence and oblivion. Truths, which are pernicious to society, if any such there be, will yield to errors, which are salutary and advantageous. (Second Enquiry, 9.14)
Hume is tactfully quiet about the source (philosophers, poets, politicians, historians?) of the Noble Lie. One might say, they emerge spontaneously, but that, of course, defers the problem (and ignores the ominous nature of the ways mankind silences and causes oblivion). It is no surprise that we often find Hayekian praises of spontaneous order and (near blind) submission to law together (see this brilliant analysis). But Hume's position presupposes that philosophically such an inquiry into origins is possible--they are "philosophical truth," after all. Hume is suggesting that society need not hear the whole philosophical truth (and he seems to be thinking that social truth and philosophical truth can come apart dramatically). That is to say, self-command is a prudential virtue to a (healthy) philosopher. (Recall the significance of Abe Stone's work on Carnap.) And we should not be surprised that Smith praised Hume's "magnanimity and firmness" while facing death. As Adam Smith puts it, "The most perfect knowledge, if it is not supported by the most perfect self-command, will not always enable him to do his duty." (The Theory of Moral Sentiments, 6 has a more complex relationship to self-command as Ryan Hanley has explored in his book.)
Now, for all of Kant's talk of "futility," his stated position is compatible with the idea that a philosopher can pursue a private, disinterested inquiry into the origin of the law, as if it were an aesthetic enterprise. It is just that such inquiry (because destabilizing) could not serve a public role. If anything, given the way taboos operate, Kant almost invites his most daring readers to engage in such an inquiry. It's as if he stamps "top-secret" on the topic. (Or to put it more cryptically: a dutiful soul respects the taboo, a more courageous soul enters the forbidden zone; sometimes taboos are transgressed in the grip of theodicy.) As Žižek "naively" (in Schiller's sense) questions it (commenting on Kant & Wittgenstein): "if one declares that one cannot, at any rate, say anything...why add again the totally redundant statement that one must not say anything about it, that one must be quiet?"
I cannot resist adding an unscientific postscript: in "What is a Classic," Coetzee promotes the pleasing philosophic prophecy that regardless of the destiny of the chance-ridden market-place (codified as the efficient market hypothesis in which randomness and efficiency turn out to be extensionally equivalent), crafts-folk can maintain a sense of quality independent of the judgments of the market-place and keep alive a secret history of performance and criticism. We need not be blind to the psycho-analytic anxiety in Coetzee's remarks, to observe that it would be amusing if somewhere historians were performing such a dangerous task.