 Considerations as reviewed in  Section 1.1  according to which the laws, constants and boundary conditions in our universe are fine-tuned for life are based on investigations of physical theories and their parameter spaces. It may therefore seem natural to expect that the relevant probabilities in the light of which fine-tuning for life is improbable will be physical probabilities. On closer inspection, however, it is difficult to see how this could be the case: according to the standard view of physical possibility, alternative physical laws and constants are physically impossible by the definition of physical possibility (Colyvan et al. 2005: 329). Accordingly, alternative laws and constants trivially have physical probability zero, whereas the actual laws and constants have physical probability one. If the laws and constants that physics has so far determined turned out to be merely effective laws and constants fixed by some random process in the early universe which might be governed by more fundamental physical laws, it would start to make sense to apply the concept of physical probability to those effective laws and constants (Juhl 2006: 270). However, the fine-tuning considerations as outlined in  Section 1.1  do not seem to be based on speculations about any such process, so they do not seem to implicitly rely on the notion of physical probability in that sense.