In 2003, perhaps 200 million Americans supported the invasion of Iraq. As late as 2007, around 100 million still believed in the war.
With a population of 80 million, Germany almost won two world wars against great powers to the west and east. Yet pro-war Americans, who claimed that patriotism was synonymous with supporting the war, couldn't get enough volunteers from their own ranks to successfully conquer the impoverished third-world countries of Iraq and Afghanistan. Too many young Republicans chose to party in college instead, even as they claimed their intellectual and moral superiority over their "liberal" peers and professors, whom they called "anti-American" and "traitors."
Their political ideals said "fight!" Their self-interest said "college!"
Such people appear cowardly, but where were they wrong, exactly? Was it their support for a wrong-headed and unjust war, or the fact that they were doing what was best for themselves?
From time to time Presidential nominees to senior Cabinet positions or judicial posts run into snags when it's discovered they hired undocumented immigrants as domestic help, or otherwise committed employer tax violations. These nominees would have been happy to enforce onerous regulations on others which they neglected to comply with themselves.
Where were these nominees wrong? In the fact that they sought positions of power in order to persecute others who fail to comply with complicated rules, or the fact that they hired willing workers for a mutually-agreed upon wage?
In the end, it looks to me that such "cowards" and "hypocrites" behaved appropriately when they went against their stated principles and ideals. It is their ideals - using the government to murder harmless people overseas or to harass American citizens trying to make a living - that were wrong.
I'm singling out these examples to illustrate that it's easy for self-interest to go against the ideal. Idealism appeals to our hearts and minds. Idealism appeals to the way we want things to be, and to what we believe is best.
Self-interest, however, appeals to our souls and stomachs. By "soul" I mean the part of us that tells us what we really value most, not to what we think we "ought" to value most. The soul tends to abhor abstractions. At its most noble, the soul may lead one to starve so that one's child may live. The soul may lead a man to jump into the sea so that a woman could get into the lifeboat. But it is a rare soul indeed that would risk one's life to serve the interests of politicians and the military bureaucracy under the guise of abstract concepts like Freedom and Democracy. That's why less than one percent of the American people have ever served in Iraq or Afghanistan.
(And most of them, though they may be proud of their service, enlisted mainly because of the lack of employment prospects or because they needed money for college. They're risking their lives for money, not for principle.)
By "stomachs" I mean the instinct to survive and to be fed, and to provide for those whom one loves.
In non-desperate situations, we feel free to call college Republicans "cowards" for not enlisting, or progressive lawyers "hypocrites" for violating the very laws they'd zealously enforce. In desperate situations, however, any one of us may behave as they do. The fundamentalist Christian may take the job at the casino. The libertarian may apply to the Postal Service. Ideals are a luxury that people with no money in the bank can't afford.
In non-desperate situations, one's ideals can override one's self-interest at any given time. In desperate situations, however, souls and stomachs override hearts and minds. People will do what they have to do to get by. This itself isn't "ideal," but it's reality.
The question is, what is wrong with the reality? Why not recognize that we're all in the same boat with basically the same drives? Why not make reality the ideal?
The purpose of idealism is actually psychological slavery, which transforms into political slavery. Its purpose is to persuade you, through various means beginning at a very young age, that how you actually think and feel is not how you ought to think and feel. It's purpose is to make you feel ashamed of yourself and to project your own divided self onto the rest of the world: "The world is both good and bad. Yes, I have bad in me, but I believe in the good. Those other people (of the other party, religion, or country) may have some good in them but they believe in the bad and are therefore bad."
Idealism can be summarized as this: "The standards I myself frequently fail to live up to should nonetheless be imposed on everyone else by force."
Take away these ideals, and we recognize that almost everyone is really just trying to find a way to provide for themselves and their loved ones. Our hearts and minds could then serve our own needs rather than make war on the external world.
Self-interest is, ultimately, about exactly that: what's best for oneself and the people and values one really loves most. Idealism, however, is about creating disputes and wars against other people because of what they believe.
I'd rather follow a realist philosophy. Peace and justice can exist only if we recognized how people actually think and act, and if we stopped wishing that they behaved differently.