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"Utopia" can be defined as "any visionary system of political or social perfection," but we most often hear it in the derogatory sense of "an impractical, idealistic scheme for social and political reform," and it falls thus from the lips of those walnut-brained idiots to whom we've just earnestly explained our vision of how a free-market society would be both peaceful and prosperous, but whose imaginations cannot grasp it. With a form of cognitive dissonance they therefore try to reflect the blame for their failure back to us, and sneer "sounds great, kiddo, but it would never work"; or if their manners are more refined, the sneer is replaced by a condescending smile. A classic case of intellectual sour grapes.
I like to define the word more exactly as "a social system which, if established, could not survive"--that is, one that would be inherently unstable. Let's see how a few alternative, possible social systems match up to that.
History has been marred by many of these, though they have seldom been "absolute"--the King has had to share some power with a small number of associates often called "aristocrats." In fact, in Anglo-American history, the last absolute monarch was John, who gave up an important measure of power in 1215 so as to buy his peers' cooperation in a war upon Islam. They did a useful job of work that year; we have juries to this day as a result--though it's an ironic reflection on the nature of politics that the price of that advantage has been the long-memoried enmity of the Muslim world.
Autocracies work for a while, but not for long. We've managed for almost 800 years without one, and before 1215 the English monarchy had been near-absolute only since 1066, when the Normans conquered the island and William portioned out its counties to his friends; prior to that, the Angles, Saxons and Danes had organized themselves with leaders called kings, but who led with a deal more consensus. In modern times the autocrat Saddam Hussein came to a well-known sticky end in Iraq , and Hitler and Mussolini to even stickier ones in 1945. Kim Jong Il in North Korea has had a good innings, but I sense that his day will soon come. Autocracies don't last; it's a plain fact of history. Reason: sooner or later, some members of the ruled population ask the key question about why one particular person should rule the rest, and when no credible answer emerges, they find a way to displace him. Therefore, they are Utopian.
This is closely similar, but more cunning: such power as the autocrat retains, he tries to justify by claiming God gave it to him. A supreme being is invented, whose nature and existence is guaranteed by a whole set of other men called "priests" who must be disinterested because they take vows of poverty, have a hotline to the Deity, and play no part in the affairs of State--so are clearly telling the truth, aren't they? In reality, they do exercise a great deal of power, granted to them by the King whom they validate, but behind the scenes. It's a neat, symbiotic relationship--not unlike the one between the FedGov and the FedBank, that private club of bankers called the "Federal Reserve" whose pieces of paper we are forced to accept in settlement of debts.
There are quite a few theocracies around today, though not in the formerly Christian world; the Age of Reason was able to demolish the old fiction about the "Divine Right of Kings." But the Age of Reason hasn't yet arrived in the Muslim one, so the idea of an autocrat ruling by appointment of the Creator is not yet everywhere seen for the scam that it is. Daily there is news of one in Iran , and until it was displaced recently, there was one in Afghanistan . Theocrats are fighting hard to restore it, and another in Iraq is doing likewise. The gullibility of Muslims seems so great that one can never be sure that others will not spring up. Even now, however, theocracies don't last long; the theocrats tend to believe their own propaganda, start to do outrageous things, and so get overthrown. It's an unstable arrangement, being founded as it is on elaborate fairy tales--a Utopia.
Here is the cunning deception that emerged from the Age of Reason, which correctly determined that nobody had any right permanently to rule his fellow-humans, but incorrectly supposed that someone had to rule them and so invented the scheme whereby there is a turnover or cycling of power according to the will of the majority being ruled. Carefully the voting population is never asked, "Do you want to be ruled?" but only "Who do you want to rule you next?" This was expected to be more stable, since any deeply unpopular ruler could spoil things only for a short time, and so there would be no need for violent overthrow--and it must be said that that important aspect of the scheme has worked quite well; today for example, the American King George is profoundly unpopular, but nobody organizes an uprising because he's leaving anyway next January. Unless, that is, Alex Knight's prediction  should prove correct; though in that case, democracy will have ended and my point been proven.
Can we, then, say that democracies are stable and therefore non-Utopian?
I reason for the negative. They do tend to last a long time, but no they are not inherently stable because they still violate human nature, like all other systems of rule. Human nature is inherently something that should not be ruled at all, except by the individual human himself. Why? Because human beings are self-owners, a fact that can be verified by eliminating the only alternative (that we are each rightly owned by someone else). If that were so, the unanswerable questions arise: By whom? And by what right? Since then we are self-owners, we cannot properly be ruled by anyone at all, and any such rule as does take place is a fundamental violation of our most basic human right, and that holds good for demo- or any other -cracy. Accordingly, democratic rule rests upon a wholly false premise, sows the seeds of its own destruction, hence is unstable and therefore Utopian.
Then there is a second reason, often said to have been identified by Alexander Tytler : democracies can exist only until the voters discover that they can vote themselves largesse. Then social discord grows until the system collapses and gets replaced by something worse. We are in that phase right now, in the USA . No matter who gets elected, massive wealth transfers take place from the productive to the politically well connected, and society divides into two classes, the productive and the parasitic. Adjustments are made at the margin whenever Tweedle Dum replaces Tweedle Dee, but the word "entitlement" has now been well distorted over several generations to mean that (for one example) the older generation is entitled to be kept comfortable by the younger one. This can continue only for as long as the younger generation continues to be fooled into supposing it inevitable; already those taxes have been raised and "benefits" have been reduced so as to postpone the day of reckoning, and the only two future options are to reduce them further or raise SS taxes further. Neither will suffice; the system is for that reason alone inherently unstable, or Utopian. It will inevitably collapse.
That's a very poor name for the "social system" I'd like to mention here, but I can't think of a better: I'm supposing that whatever government existed previously ended, perhaps suddenly, perhaps because its own gross mismanagement of the economy caused a meltdown, perhaps because a determined group of nihilists monkeywrenched the system, or whatever.
Many would say that that is "anarchy"--but of course it's no such thing; there is a world of difference between chaos and individual self-rule. That kind of society would come about, however, if in some way government were abolished without universal consent; and there would be ample cause of instability. By "consent," I mean that every member of the society understands what anarchism is and therefore desires it. If the society includes those who hanker for some form of collectivism, i.e., a system in which some rule over and live at the expense of others, it would be Utopian. Merely to wave a magic wand to abolish government tomorrow will not do; nor, alas, will it suffice merely to wait until government destroys itself, as many earnest people now say they think it's poised to do.
This is also the fatal flaw, I think, in the view that says that civil disobedience is the key to bringing about a free-market, anarchist society. To refuse to obey laws is incredibly brave, and I admire greatly the courage of those who do it. But aside from its devastating effect on the lives of the CDers themselves, its effect on government is not conducive, IMHO, to its orderly termination. Yes, we each need to set limits on the laws we'll obey--but as a matter of moral conscience, not as a technique for terminating its existence. For example one might refuse a draft, another might refuse to expose his children to its indoctrinators, and so on. Commendable, but at best, that will only limit its growth, not cause its disappearance.
Suppose that CD "works." Suppose it is so widespread that government ceases to do whatever it's supposed to do. Among its activities are a few that are useful, in the sense that if nobody did them, there would be chaos. Nobody repairs the traffic lights, there would be gridlock; nobody renews passports, international trade would grind to a halt; nobody collects trash, there would be a plague, and so on. Suppose there were a "tax strike" so that government had little or no revenue; it would have to lay off all employees and would cease to operate. Is that good news? No, not in and of itself! It's fabulous news, but only if the free market is ready and prepared to step in and take its place! I've said it here before and will say it again: the essential prerequisite is universal re-education. Absent that, even a total collapse of government would result not in anarchy but in chaos. And chaos is totally unstable; a Utopia as well as a nightmare.
This hasn't been tried yet, though we're all eager here to change that fact. Here's why, in contrast to all systems of rule which are necessarily unstable and so Utopian, a society without any ruler is inherently stable and therefore non-Utopian.
The reason is simply that a no-ruler society is the only type that fits human nature; i.e., the universal right in practice for each to rule himself or herself. Since nobody is being forced to do something he doesn't want to do, there is no source of discord, discontent, complaint, resentment, revolution. Instability must have a cause; anarchism  removes all known causes. An analogy with Newton 's First Law of Motion--that of inertia--applies: "An object in motion will remain in motion unless acted upon by a force," and that applies whether the object's velocity is zero or non-zero.
Absence of a ruler doesn't mean that an anarchist society would have no rules, just that it would have no rulers. Rules are useful, to prevent chaos (of which one definition is that a stimulus is frequently not followed by its predictable response). In a ruled society, those rules are set by the ruler; in an anarchist society, they are set by each person governed by them, by means of explicit, voluntary contracts drawn between two or more people. If there's no contract, then there's no rule or obligation; or if there is a contract, the rules applicable are those which it specifies, and those alone; and any failure to honor them results in a serious loss of reputation, which hobbles the culprit's ability to make future agreements.
Thus, the fundamental right of self-ownership is fully honored; if you want zero obligation, you sign no contract! In practice, since there is often much to gain by making contracts with others (often called the "division of labor"), we can expect that most people will choose to enter some--but nothing compels anyone to do so except his own wish to engage in exchange rather than to grow his own food and weave his own clothing. The market is wholly free.
Conclusion: The only system of society that is inherently stable and non-Utopian is the very one which all non-anarchists, who all live in and support an actually Utopian society but don't know it or at least admit it, brush off as Utopian. That's a really handy trick of language, a neat device of Newspeak--where "War is Peace ; Freedom is Slavery; Ignorance is Strength." If I thought they knew what they were doing, I'd blame them as wicked conspirators.
But I won't bother. They're not that smart.