Chapter 2 begins to develop the deontological argument in support of the rights-based interpretation of the precautionary principle that Chapter 1 explored. Briefly, Chapter 2 argues that the equal moral standing of others demands that we respect them as ends in themselves, as autonomous moral agents. Yet to expose others to uncertain environmental threats without first trying to mitigate the potential for harm is to gamble with their welfare, and therefore to disrespect their moral standing. In this way, to avoid wrongdoing, we are obliged to take reasonable measures to strive to prevent exposing others to potential harm. After exploring the Kantian foundation for this argument, this chapter also delineates two qualifications that are necessary to justify a pro tanto duty to exercise due care. The first is that uncertainty can vary across contexts and can be more or less pronounced, which determines when an obligation of due care exists and how strong the duty is. To clarify this notion, a distinction is drawn between having reasons to exercise due care and having those reasons translate into a duty of due care. The second qualification is that a feasible standard of due care must be sensitive to context, which implies that what precaution may require will vary across contexts and actors.