It is almost universally acknowledged that risks have to be weighed against benefits, but there are different ways to perform the weighing. In conventional risk analysis, collectivist risk-weighing is the standard. This means that an option is accepted if the sum of all individual benefits outweighs the sum of all individual risks. In practices originating in clinical medicine, such as ethical appraisals of clinical trials, individualist risk-weighing is the standard. This implies a much stricter criterion for risk acceptance, namely that (...) the risk to which each individual is exposed should be outweighed by benefits for that same individual. The different choices of risk-weighing methods in different policy areas seem to have emerged from traditional thought patterns and social relations, rather than from explicit deliberations on possible justifications for the alternative ways to weigh risks against benefits. It is not obvious how the prevalent differences in risk-weighing practices can be reconstructed in terms of consistent underlying principles of preventive health or social priority-setting. (shrink)