The Crank's First Principle is thus:
The most important function of government is to provide for the common defense, against threats both foreign and domestic.
Not exactly revolutionary (or would that be reactionary?), but it is profound. And I don't mean profound in the casual, everyday sense of having a particularly keen insight; I mean profound in the less common usage, of being broadly and inclusively significant in that it bears on and ultimately informs nearly all of my beliefs regarding government.
George Bernard Shaw claimed, "Morals are a luxury of the rich." I think Shaw missed the mark slightly--morals are more akin to a luxury of the secure. Riches are one, obvious form of security, but they are in turn only a form of security because we have a civil society, one in which there are rules that set limits on our actions. Ten kajillion dollars in the bank means very little if the manager can clean out the account without a real, existential threat of punishment. Hiring a legion of private bodyguards is no guarantee, even in a society of rules (witness Caligula), but in an environment with no structure, no laws, or even with laws but no means to enforce them, one's security is guaranteed only as long as it takes one of the knuckle-draggers to decide he'd rather give orders than take them.
Without a commitment to providing for defense, any group of people (can it even be called a society without this precondition?) is inevitably doomed to anarchy and violence--if not from dissensions within, than certainly from forces without, because sooner or later someone will want what that group has and will resolve to take it, by any means necessary. This "society" is doomed to fall into a Hobbesian jungle scenario. This is inevitable because of human nature. It is rational to pursue what one wants and needs, and it's hard to convince a man that killing you for your food is wrong when he is starving to death and you have no way to stop him. This is simply a principle of survival, as primitive and as savage as the reptillian brain that still plays a key role in motivations despite uncounted generations for evolution to have effected a change. The suffering of a Ghandi in a hunger strike is considered noble precisely because it is such an abnegation of a root survival instinct that the average person can barely conceive of carrying out such a plan, yet alone following through on it. In a society without laws, would such a display have any meaning? It is much more likely that in the jungle Ghandi would simply be killed if he was perceived to have anything of value, or ignored if he was perceived to have nothing of value. Only laws, and the promise/threat of enforcement of those laws with punishments for transgressions, makes the concept of civil disobedience possible.
So, enter the need for common defense. The defense must first necessarily protect against outsiders, for if it doesn't they will be free to violate the society and impose their own rule upon it--history is so rife with examples that it would be insulting to name specifics here. Without this security, there can be no faith in the government, and hence no faith in anything else it may do, for it is all as fragile as a sandcastle under the foot of the next beach bully to come along.
Once the outsiders are (theoretically) eliminated as a threat, the protection of the insiders from each other must be the next step. Criminals are, in a very real sense, the outsiders within the society. They coexist with members of the society, to an extent, but also have put themselves above the rules of the society to gain some advantage over those who follow the rules. In more elemental terms, a criminal is someone who takes someone else's desserts for himself, contravening justice, vis-a-vis that everyone should get their own desserts, and neither more nor less. Without means to guarantee justice, or at least a reasonable approximation of justice, the criminals can run amok internally and render all other tasks of the government meaningless, leading inevitably to anarchy and Hobbesian savagery. Only with external threats turned aside and internal justice preserved can other, secondary functions of government hope to succeed.