 Such controversies can be clarified with the help of a simple but illustrative model of how scientific data influence both scientific judgments and practical decisions (Hansson 2008). Scientific knowledge begins with data that originate in experiments and other observations. (See Figure 1.) Through a process of critical assessment, these data give rise to the scientific corpus (arrow 1). Roughly speaking, the corpus consists of those statements that could, for the time being, legitimately be made without reservation in a (sufficiently detailed) textbook. When determining whether or not a scientific hypothesis should be accepted, for the time being, as part of the corpus, the onus of proof falls on its adherents. Similarly, those who claim the existence of an as yet unproven phenomenon have the burden of proof. These proof standards are essential for the integrity of science. 