by Patrick Appel

Bryan Caplan quotes this passage from Leon Kass's The Wisdom of Repugnance:

[R]epugnance is the emotional expression of deep wisdom, beyond reason's power fully to articulate it. Can anyone really give an argument fully adequate to the horror which is father-daughter incest (even with consent), or having sex with animals, or mutilating a corpse, or eating human flesh, or even just (just!) raping or murdering another human being? Would anybody's failure to give full rational justification for his or her revulsion at these practices make that revulsion ethically suspect?

Caplan lists some rules for when we should discount our repugnance and defends human cloning against Kass's critique. I side with Kass on human cloning because of unnecessary pain and suffering caused to the numerous unsuccessful or partially successful trial clones:

Reproductive cloning is expensive and highly inefficient. More than 90% of cloning attempts fail to produce viable offspring. More than 100 nuclear transfer procedures could be required to produce one viable clone. In addition to low success rates, cloned animals tend to have more compromised immune function and higher rates of infection, tumor growth, and other disorders. Japanese studies have shown that cloned mice live in poor health and die early. About a third of the cloned calves born alive have died young, and many of them were abnormally large. Many cloned animals have not lived long enough to generate good data about how clones age. Appearing healthy at a young age unfortunately is not a good indicator of long-term survival. Clones have been known to die mysteriously. For example, Australia's first cloned sheep appeared healthy and energetic on the day she died, and the results from her autopsy failed to determine a cause of death.

If cloning were no more dangerous than natural reproduction, I'd probably feel differently.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.