Slippery slopes crop up with startling frequency when controversial moral issues are debated. Generally, those who mount this line of argument appeal to some grim, highly undesirable state of affairs which would—they allege—inevitably ensue were society to sanction certain activities. Their reasoning is often fallacious, offering little more than an easy out for those reluctant to address problematic moral issues with the care and honesty they demand.

The article investigates the validity of two different versions of the slippery slope argument construed in relation to human gene therapy: the empirical and the conceptual argument. The empirical version holds that our accepting somatic cell therapy will eventually cause our accepting eugenic medical goals. The conceptual version holds that we are logically committed to accepting such goals once we have accepted somatic cell therapy. It is argued that neither the empirical nor the conceptual version of the argument can provide (...) a conclusive moral reason for banning somatic cell therapy. According to a third interpretation, referred to as the arbitrary result argument, the many apparent similarities between somatic cell therapy and eugenic-based human genetic engineering drive us to make principled choices concerning what differences and similarities between the two practices should be regarded as morally (ir)relevant. Decisions of this kind are likely to have unpredictable moral consequences. Thus formulated, the slippery slope argument has much plausibility. One objects to somatic cell therapy not so much because of what is at the bottom of the slope on which it lies, but because it is on a slope of which one does not know what is at the bottom. While the arbitrary result argument does not provide a conclusive reason for prohibiting human gene therapy, it reminds of a very important thing: when making bioethical decisions, we should be as specific and as consistent as possible about our basic moral and medical concepts. (shrink)

Brian Leiter’s Why Tolerate Religion? valuably clarifies the issues involved in granting religion-specific accommodations to laws and policies of general application. His arguments are careful, rigorous, and fair, and in rejecting the deontological arguments for religion-specific accommodations he seems to me largely correct. But when he turns to arguing against the utilitarian case for such accommodations, he employs a seemingly non-standard sense of utilitarianism in which demands of principled consistency constrain what would otherwise be utilitarian welfare-maximization. A more traditional and (...) stronger version of utilitarianism, however, has room for seemingly unprincipled or even irrational distinctions as long as employing those distinctions is utility- or welfare-maximizing. And thus although Leiter’s arguments against the deontological justifications for religion-specific accommodations are largely successful, his arguments against utilitarian justifications, by relying more heavily on the notion of “principle” than a utilitarian should accept, are open to challenge. (shrink)

Causal slippery slope arguments with moral conclusions are sometimes stronger than we think. Their strength may be missed either by overlooking the problems of human nature which support the arguments or, upon seeing the problems, by underestimating their influence upon human behaviour. This article aims to correct the oversight and the misjudgement by looking in some detail at four interrelated problems of human nature which have a direct bearing upon moral causal slope arguments.