Concerning evidence there are two important questions: (1) what is going to count as evidence? and (2) what are the appropriate means for employing evidence? These two problems pervade the analysis of the scientific process. They are with us as much today as in Galileo’s time. For example, with respect to contemporary arguments between Evolutionists and Scientific Creationists, if the issue is taken in its cognitive rather than its political dimension, the entire discussion turns on the criteria for acceptable, evidence, i.e, the heart of the problem is disagreement over the status of the data one wants to invoke as evidence.

Many of the disputes between Galileo and his philosophical, interlocutors in his Dialogue on the Two Chief World Systems turn on some of the same issues that bedevil the debate between evolutionists and creationists, i.e., what is going to count as evidence?