  Second, the number of design problems is equal to the number of distinct environmental features that affect survival, and of course reproduction, and this number is probably uncountable. Accordingly, prima facie, the proposed definition provides no hope of cardinal or even ordinal measurement that would enable us to predict or explain quantitatively differences in rates of reproduction, and the evolutionary processes that depend on these rates. Moreover, ecological fitness accounts may not have provided a satisfactory story about how to carve up the relevant reference environment that is supposed to have an impact on the survival of said organisms (Abrams 2009). It is no wonder that biologists, sensible of the importance of predictive precision and explanatory testability, have had little truck with ecological fitness and have defined ‘\(x\) is fitter than \(y\)’ in terms of quantitatively measurable reproductive rates. This tendency of course simply adds force to the original argument. If the only way to make fitness differences scientifically tractable is to trivialize the theory, so much the worse for the theory.