Of all the arguments against stem cell research, the lamest has to be that "it would put us on a slippery slope." But since this case comes from the same precincts that gave us "gay marriage will lead to incest and man-on-dog sex," I suppose I shouldn't be surprised.
The anti-stem-cell slippery slope argument goes like this: If you permit scientists to destroy human embryos for the purpose of research, it's a slippery slope from there to killing human fetuses in order to harvest tissue, and from there to euthanizing disabled or terminally ill people to harvest their organs, and from there to human cloning and human-animal hybrids, and if making chimeras is okay, well then Dr. Frankenstein must also be okay, and Dr. Mengele, too, and before you know it, it's one long hapless inevitable slide from high-minded medicine to the Nazis.
This is not the same as the argument over when human life begins. If the answer to that is, when a sperm cell fertilizes an egg, then a single-cell zygote is a already a tiny human being with a soul, and anything that stops it from becoming a fully-developed person is evil and must be outlawed. This way of thinking leads not only to ruling out exceptions for abortion in cases of rape, incest, a fatal genetic disorder or a threat to the mother's health; it also means a ban on in vitro fertilization, because that technique also leads to the destruction of superfluous embryos, unless of course you're the octo-mom, but let's not go there just now.
The when-life-begins argument is about logical consistency. Life is life, period, and no compromise, even for the most compassionate of reasons, is possible. How then do its adherents justify, say, killing people in self-defense, or in war? The answer is that those circumstances are sanctioned by the Bible, every word of which was divinely written. If that's fundamentally what you believe, then there's no slippery slope to be concerned about, because you never need to make exceptions to the rules, because all the rules come straight from the Creator.
But the slippery slope argument is all about exceptions. It doesn't require believing that legal rules come from moral rules that in turn come from on high. Instead, it's about what you believe coming from down below, from our innards and our evolutionary forebears. Call it hardwiring, or call it psychology; it doesn't matter. What counts is a fundamentalism about human nature.
This view of how people are, deep down, is implicit in the metaphor itself. Picture a person on a steep mountaintop. Then imagine him taking a step off the summit and onto an ice-covered slope. (Please don't be offended that I'm not saying "him or her"; this guy has got to be pretty stupid to take that step.) And following that step comes a cartoonish blur of whirling legs and arms, and before you know it the guy is tumbling ass over teakettle down the slope, a human snowball banging into trees, helplessly accelerating toward the fatal crevasse below.
What this case against stem cell research is saying is that people are basically animals, slaves to their appetites, incapable of restraining themselves, biologically unequipped to make complex rules, or draw fine distinctions, or debate exceptions, or enforce differences. If we make one exception, and permit a scientist to culture stem cells from discarded human blastocysts, then when that scientist wants to make cowumans and humabbits, society will be totally flummoxed, completely paralyzed, incapable of drawing a legal line and saying no.
If this were actually true, then the message society sends when police don't stop everyone over the speed limit on the freeway is that it must also be okay to be a hit-and-run driver. You know, there's a slippery slope between not arresting someone for smoking a joint and letting drug cartels destroy our cities. If you can restrict the sale of semi-automatic rifles, then you can ban the right to bear arms. If a shoplifter gets off easy, what's to stop a Bernie Madoff from being allowed to walk? If you make hate speech a crime, then it won't be long before free speech is a crime.
During George W. Bush's long summer vacation in 2001 -- the summer when he dismissed the CIA briefer who told him that Bin Laden was determined to strike in the United States with "All right, you've covered your ass now" -- the big news out of Crawford was his Solomonic decision to permit federally-funded research only on the 78 stem-cell lines already created in privately-funded labs. Those murders, he signaled to his base, had already been committed, so we might as well get some good out of the crimes.
It turns out that only about 20 of those lines were actually usable in laboratories. As a result, over these last 7 1/2 years, when stem-cell researchers might have been racing toward therapies for diseases like juvenile diabetes, cystic fibrosis and muscular dystrophy, they have instead had federal anvils chained to their ankles.
Today, some of those protesting President Obama's reversal of President Bush's limits are saying that we don't need any new lines of embryonic stem cells, because recently discovered techniques, like reprogramming human skin cells into iPS -- induced pluripotent stem cells -- make it unnecessary to depend on embryos. But the potential of iPS is still unclear; at least as promising and worth pursuing are the hundreds of stem cell lines that were created without federal funding during the Bush years, but have not yet benefited from the kind of balls-to-the-wall research that only the National Institutes of Health can support.
If God is dead, Dostoevsky had Ivan Karamazov say, then anything is possible. This turns out to be exactly wrong. In fact, you can build a just society on the basis of the rule of law, and you can build a good society on the basis of human culture and humanistic values. Despite what Bill O'Reilly says, a secular society is not the same as an immoral society. Every American has the right to choose a God to believe in, or not. But no Americans have the right to impose their own theistic absolutes, or their own dark views of human nature, on anyone else. That's what it means to be a pluralistic democratic society. And the last time I looked, being a democracy is not the first step down a slippery slope.