Before beginning a consideration of political arrangements, one simply must understand what man is. Failing that, man will bite you every time.
You will have noticed that for the left, the question doesn't come up, since they pretend not to believe in human nature. However, they are never consistent about this, and will hide behind it when it is expedient to do so.
For example, they simultaneously tell us that gender is a social construct but that homosexuality is genetically fixed. Or that women are the same as men, but that we need to lower standards for women.
The left argues that all cultures are equally valuable, but any culture is only valuable to the extent that it promotes human flourishing, or the actualization of human potential.
However, if we fail to respect human nature, it is difficult to actualize human potential. In this regard, it is useful to think of human nature as a fixed variable, human potential as the dependent variable. Quash or maim human nature, and human potential will be stillborn -- as, for example, in the Arab Muslim world.
"Politics ought to be adjusted not to human reasonings but to human nature, of which reason is but a part, and by no means the greatest part" (Burke, in Levin). Burke made this comment in the context of explaining how the American colonists "had over time developed robust habits of freedom and an independent spirit," such that "some reasonable effort must be made to accommodate their character."
In other words, reason had to bow before our wholly unreasonable love of freedom!
Which sounds odd, but we are clearly having the same argument today, with the Obama administration constantly undermining our "useless" freedom in the name of some "reasonable" goal, such as socialized medicine. It doesn't matter to Obama -- and to the left -- that his proposals go against our nature. What is the point of freedom, when we are in a crisis! And for the left, we are always in a crisis, so there is always a good reason to revoke our freedoms.
For example, the left manufactured a "healthcare crisis" in order to ram through Obamacare. Likewise, the government-caused mortgage crisis was the pretext to give us Porkulus.
You may not remember the "homeless crisis" during the Reagan years, because it magically disappeared once he left office. Then there was the "energy crisis" of the Carter years. To see just how silly that one was, this is all you need to know: the more oil we use, the more we find. It's like the free market works or something.
Before that was the Poverty Crisis of the 1960s, which is still with us today despite (or because of) trillions of dollars thrown at it.
And the Mother of All Crises was the Great Depression. That is indeed the archetype, because it was caused and prolonged by the very government interventions that were supposed to have ameliorated it. The left is still dining out on the myth of FDR saving capitalism from itself.
At the moment we have the Immigration Crisis and the Global Warming Crisis.
This is another fine example of the intellectual incoherence of the left, because -- using their logic -- the more immigrants that come to America, the worse the global warming, because these immigrants will leave a much larger carbon footprint here than in Central America. If there is really a Global Warming Crisis, then we must turn away immigrants for their own good and for the sake of the planet.
In Liberty's Secrets, Charles provides numerous examples of how the Founders first meditated deeply on human nature before going on to the secondary task of constructing a political system. Because they put things in their proper order, they were under no delusion that the purpose of politics was to change human nature. Rather, they took human beings as they found them, with all their greed, vanity, laziness, selfishness, lust for power, and desire for unfair advantage.
They also looked closely at history, being that history is just the prolongation of human nature. To put it another way, if you want to know what human beings are like, consider what they do. If you are honest, you will strain to produce even a tie between man's good and bad qualities and attainments. I remember Charles Murray addressing this in his Human Accomplishment:
What "can Homo sapiens brag about -- not as individuals, but as a species?... Military accomplishment is out -- putting 'Defeated Hitler' on the human resume is too much like putting 'beat my drug habit' on a personal one."
Likewise, governance and commerce "are akin to paying the rent and putting food on the table..." On the whole, "We human beings are in many ways a sorry lot, prone to every manner of vanity and error. The human march forward has been filled with wrong turns, backsliding, and horrible crimes."
And the most horrible atrocities have been committed by secular utopians who deny human nature and insist that humans are infinitely malleable products of their environment or class.
"So what was the secret of the Founders' insights?... The answer is very simple: they understood human nature and history. That is it" (Charles).
"[I]t was not as if we could evolve or mold human nature into whatever pleasing image we sought to achieve. It is what it is, but even amid the sobering reality of its excesses and imperfections, it was capable of rising above them to achieve great things, though never on a permanent basis. The 'dark side' always had to be kept in check through constant and unceasing vigilance" (ibid.).
There are many priceless quotes in Liberty's Secrets, but I think my favorite is this, from John Adams. Imagine if he could see the fascists on our university campuses today!
Posterity! You will never know how much it cost the present generation to preserve your freedom! I hope you make good use of it. If you do not, I shall repent in heaven that I ever took half the pains to preserve it.
Bad news/good news -- they'll never actualize their potential, but at least they'll destroy our culture: "These people will produce nothing. They will create no great art, write no symphonies, conjure no novels that speak across the decades, sculpt nothing of beauty. The world outside the bubble is irredeemable. It cannot, of course, be remade all at once, but tomorrow's a new day. Rome wasn't wrecked in a day" (Lileks).