 The problem with this argument is that the risks of research often are additive rather than substitutive. For example, participation in a study might require the participant to drive to the clinic for a research visit. The present defense succeeds to the extent that this trip replaces another trip in the car, or some similarly risky activity in which the participant would have been otherwise involved. In practice, this often is not the case. The participant instead may simply put off the trip to the mall until after the research visit. In that case, the participant’s risk of serious injury from a car trip may be doubled as a result of her participation in research. Moreover, we accept many risks in daily life because the relevant activities offer those who pursue them a chance of personal benefit. We allow children to take the bus because we assume that the benefits of receiving an education justify the risks. The fact that we accept these risks given the potential benefits provides no reason to think that the same risks or even the same level of risk would be acceptable in the context of an activity which offers no chance of medical benefit. Finally, applied strictly, this justification seems to imply that investigators should evaluate what risks individuals would face if they did not enroll in the research, and enroll only those who would otherwise face similar or greater levels of risk.