Beliefs cluster. If you find out someone is an environmentalist, she probably also is sympathetic to rehabilitating offenders, affirmative action, generous welfare programs, and gay marriage, is a secularist and a professor or student. If you find out someone favors a strong military, he probably also "supports judicial restraint, laissez-faire economic policy, is more likely to be pragmatic than idealistic, censorious than permissive, meritocratic than egalitarian, and gradualist than revolutionary." If you find out someone is religious, she probably also supports lower taxes.
Here's a game to play while driving. When you see an activist-like bumper sticker on the car in front of you, guess the person's beliefs. For example, if I see a bumper sticker for the National Organization for Women with a pro-choice message, I bet I can accurately predict 95% of their beliefs on political and social issues.
Thomas Sowell has offered an audacious explanation for why beliefs cluster like they do: the collections each reflect a different fundamental view of human nature. Sowell sorts human nature into two camps: the Tragic Vision and the Utopian Vision. Steven Pinker summarizes it in The Blank Slate, which is where the quote in my first paragraph comes from. Excerpt:
In the Tragic Vision, humans are inherently limited in knowledge, wisdom, and virtue, and all social arrangements must acknowledge those limits. "Mortal things suit mortals best," wrote Pindar; "from the crooked timber of humanity no truly straight thing can be made," wrote Kant. The Tragic Vision is associated with Hobbes, Burke, Smith, Alexander Hamilton, James Madison, the jurist Oliver Wendell Holmes Jr., the economists Friedrich Hayek and Milton Friedman, the philosophers Isaiah Berlin and Karl Popper, and the legal scholar Richard Posner.
In the Utopian Vision, psychological limitations are artifacts that come from our social arrangements, and we should not allow them to restrict our gaze from what is possible in a better world. Its creed might be "Some people see things as they are and ask 'why?'; I dream things that never were and ask, 'why not?'" The quote is often attributed to the icon of 1960s liberalism, Robert F. Kennedy, but it was originally penned by the Fabian socialist George Bernard Shaw (who also wrote, "There is nothing that can be changed more completely than human nature when the job is taken in hand early enough"). …
In the Tragic Vision, our moral sentiments, no matter how beneficent, overlie a deeper bedrock of selfishness. That selfishness is not the cruelty or aggression of the psychopath, but a concern for our well-being that is so much a part of our makeup that we seldom reflect on it and would waste our time lamenting it or trying to erase it.
The theory is not foolproof in approximating bundles of belief. But it does provide a useful framework to understand certain political perspectives. Usually modern liberals tend to hold the Utopian Vision and modern conservatives tend to hold the Tragic Vision of human nature.
Consider public education in America from this perspective.
Conservatives are generally skeptical of the government monopoly of public schools. The Tragic Vision emphasizes the bedrock of selfishness in human nature, and conservatives see public school teachers and their unions as selfish, greedy economic actors like any other — no more, no less. The Tragic Vision emphasizes that power corrupts and even very smart people at the top can err; conservatives tend to support decentralized control and competition (through charter schools, vouchers, etc).
The Utopian Vision emphasizes the possibility for great individuals to transcend their darker self-interested temptations and fight for the "greater good." Liberals first see teachers as generous servants fulfilling an important calling, and in political debates give them corresponding deference. The Utopian Vision emphasizes equality, and liberals see government-run public schools as important instruments in this level-playing-field-for-everyone quest.
There are probably better examples of the theory at work, but it's one that jumped to mind as I ponder the state of public education.
Note that Sowell, in his book, actually uses the terms "Constrained Vision" vs. "Unconstrained Vision." The Constrained Vision sees human nature as unchanging and selfish, and the Unconstrained Vision sees human nature as malleable and perfectible.