Divergent Level-Relative Chances and the General Principle

This paper shows how to apply a particular chance-credence principle, called the General Principle, to the case of two divergent level-relative chances of a given proposition in order to single out level-relative chance that should underpin one’s credence in that proposition. It is shown that the key move hinges on the use of admissibility clause in the GP. This principle is, then, tested against the case of two divergent viability fitnesses understood as level-relative survival chances. The case is taken to show that there are situations that fall outside the scope of the admissibility clause which is essentially qualitative. As a remedy, I suggest that the GP should be endowed with a quantitative notion of admissibility. My suggestion exploits a line of thought employed by Brian Skyrms in his work on the notion of the resiliency of chance.