David Hume (1711-1776) was no hardcore libertarian, but he was a provocative thinker and a key figure in the development of liberalism. Hume helped make the Scottish Enlightenment the important period it was. He also can be fun to read. Observe this from his essay "Of the Independency of Parliament":
Political writers have established it as a maxim, that, in contriving any system of government, and fixing the several checks and controuls of the constitution, every man ought to be supposed a knave, and to have no other end, in all his actions, than private interest. By this interest we must govern him, and, by means of it, make him, notwithstanding his insatiable avarice and ambition, co-operate to public good. Without this, say they, we shall in vain boast of the advantages of any constitution, and shall find, in the end, that we have no security for our liberties or possessions, except the good-will of our rulers; that is, we shall have no security at all.
Hume here embraces the views of thinkers we may regard as the progenitors of the Public Choice school. Awareness of the problem he refers to goes back to antiquity, and it has challenged the best political thinkers. Persons do not transform into a different sort being simply because they take government jobs.
We need not accept Hume's definition of knave – someone who has no other end than his private interest — to take his point. In fact, Hume himself may not to regard the mere pursuit of private interest as the main problem. Here's what he says next:
It is, therefore, a just political maxim, that every man must be supposed a knave: Though at the same time, it appears somewhat strange, that a maxim should be true in politics, which is false in fact. But to satisfy us on this head, we may consider, that men are generally more honest in their private than in their public capacity, and will go greater lengths to serve a party, than when their own private interest is alone concerned. Honour is a great check upon mankind: But where a considerable body of men act together, this check is, in a great measure, removed; since a man is sure to be approved of by his own party, for what promotes the common interest; and he soon learns to despise the clamours of adversaries. To which we may add, that every court or senate is determined by the greater number of voices; so that, if self-interest influences only the majority, (as it will always do) the whole senate follows the allurements of this separate interest, and acts as if it contained not one member, who had any regard to public interest and liberty.
So here Hume appears to be saying that the problem is not private interest itself, but rather the institutional context in which that interest is pursued. Libertarians are familiar with the many arguments for why people are likely to act better in a private capacity than in a "public," i.e., governmental, capacity: the incentives are markedly different. In the private sphere we tend to deal with other people face to face; we bear most of the costs of our actions; and we enjoy most of the benefits. This induces a sense of responsibility, and experience is a hard teacher.
In contrast, politicians and bureaucrats spend other people's money (obtained by force), have other people do the heavy lifting (how many personally invaded Iraq?), and hardly ever suffer the consequences of their bad decisions. Even being denied reelection after a major blunder is rare. No one was fired after the 9/11 attacks or the Iraq invasion, but some were promoted or awarded Medals of Freedom. (I've previously discussed how perverse political incentives encourage voters to act irresponsibly. In politics, it's irresponsibility all the way down.)
I agree with Robert Higgs (PDF), though, that the difference between private and political actors involves more than the incentives they face. The political system itself selects for vicious persons, as F. A. Hayek discussed in chapter 10 of The Road to Serfdom, "Why the Worst Get on Top." Higgs quotes Robert Sirico's amendment of Lord Acton's famous observation, "The corrupt seek power and use it absolutely." Acton himself noted that "great men are almost always bad men."
In Hume's terms, then, individuals in the political sphere are much better sheltered from the consequences of their "knavery" than they are in the private sphere. So we should expect more of it in the former.
Leonard E. Read, a founder of the modern libertarian movement, understood this too. In his essay "On that Day Lies Began," he quoted Leo Tolstoy:
From the day when the first members of council placed exterior authority higher than interior, that is to say, recognized the decisions of men united in councils as more important and more sacred than reason and conscience; on that day began lies that caused the loss of millions of human beings and which continue their unhappy work to the present day.
Persons advocate proposals in association that they would in no circumstance practice in individual action. Honest men, by any of the common standards of honesty, will, in a board or a committee, sponsor, for instance, legal thievery — that is, they will urge the use of the political means to exact the fruits of the labor of others for the purpose of benefiting themselves, their group, or their community.
These leaders, for they have been elected or appointed to a board or a committee, do not think of themselves as having sponsored legal thievery. They think of the board, the committee, the council or the association as having taken the action. The onus of the act, to their way of thinking, is put on an abstraction which is what a board or an association is without persons.
We would avoid a lot of trouble if people kept this in mind. For example, a policy that looks good in the abstract (leaving aside the core libertarian objection to forced financing, i.e., taxation) will be interpreted and carried it out by Hume's knaves. In that light the policy might not look so good after all. This need not entail self-conscious perfidy. For a "public servant," nothing is easier than to identify his private interest with the social good.
This is what came to mind as I read The American Conservative editor Daniel McCarthy's response to my comment on his original article in defense of "liberal empire." McCarthy argues the development of liberalism in practice and thought (roughly in the classical sense) requires security, and only a global empire (as exemplified by Great Britain and then the United States) can provide that security. Insecurity, in contrast, breeds illiberalism, he writes. So if we want an enduring liberal society, we must have empire, which will necessitate judicious and limited global intervention.
I don't think things are quite so simple — intervention breeds illiberalism, and insecurity could stimulate liberal institutional responses. At any rate, this is where Hume's concern arises. McCarthy writes:
Preventing a hostile power from dominating Europe and keeping a balance in East Asia is "empire" enough. Beyond that, prosperity and industrial strength, along with our nuclear arsenal, are the keys to our security. This is a historically realistic vision, one that solves the great problems of the past—what to do about Nazi Germany or the USSR—and the otherwise insoluble problems of the present, such as what to do about the Middle East: namely, minimize our exposure to crises that we cannot fix and that do not affect the top-tier distribution of power. Today what is most ethical and what is politically and strategically realistic coincide reasonably well: we should not seek to enlarge our commitments; we should preserve our naval power; we should use diplomacy and economics to advance our interests and contain disruptive powers.
This is not a strategy of hard-heartedness toward the oppressed peoples of the world. A secure and prosperous U.S. is in a position to be an ideological counterweight to any illiberal state or insurgency, and it can act when necessary only because it does not act when not necessary.
Even if we accept (for argument's sake) McCarthy's vision as desirable, the odds of its adoption as he intends it are nil. The private interests of the political class — and those in the "private" sector for whom the political class acts — virtually guarantee that the power to police the world will be put to perverse objectives. McCarthy's criteria for a good intervention may be impeccable, but what grounds have we for confidence that the policy makers and their patrons will share those criteria? History certainly gives us no grounds. McCarthy opposed the disastrous invasion of Iraq, and he doubts that U.S. entry into World War I was a good idea. Yet the ruling elite thought both were worthwhile. Those interventions brought us the Soviet Union, Nazi Germany, and now ISIS. (I don't mean to equate the power of ISIS with that of the Bolsheviks or Nazis.) The turmoil in the Middle East demonstrates what can happen when foreign policy is shaped by narrow considerations.
McCarthy's good intentions notwithstanding, I'm fairly certain he won't be the one making foreign policy.
But the problem of private interest is not the only problem for a McCarthy-style foreign policy. The "knowledge problem" is equally devastating. Even with the best intentions, the administrators of the world hegemon must suffer a critical and insurmountable ignorance. In responding to Richard Epstein's "faulty case for intervention," economist David R. Henderson writes:
The simple fact is that when a government thousands of miles away decides to intervene, it must figure out which faction to support and has little assurance that it will support the right one. Indeed, it has little assurance that there is a right one. Thus my point above: whatever else libertarian non-interventionists believe, few of us have what Professor Epstein calls an "illusion of certainty." It is the exact opposite: we are positive that there is great uncertainty. It is this uncertainty that should, in general, cause us to pressure our government to stay out of other countries' affairs. There are many "monsters to destroy," to use John Quincy Adams's famous phrase. It is generally a bad idea to go abroad to destroy them. It is even worse if one does so by allying with other monsters.
Thus, by the "first do no harm" standard, the case for liberal empire also must fail. If we wish to achieve and maintain liberalism at home, we'll have to find means other than offensive military power.