● Two types of adaptationism are distinguished – ontological and methodological. The ontological thesis asserts that natural selection is the only important cause of the evolution of the vast majority of phenotypic traits; the methodological thesis tells scientists to construct idealized models of the evolution of phenotypic traits that ignore genetics and assume that organisms reproduce asexually. ● The ontological thesis fails to be true of a trait’s evolution if the genetic system prevents the fittest of the available traits from evolving to fixation and if the character states of present organisms are strongly influenced by the character states of their ancestors. ● An optimality model for a trait is important in evolutionary biology, even if the individuals in the population do not have the optimal trait value. ● Since science often progresses when different investigators adopt different approaches to the same problem, evolutionary biology may benefit by having some investigators be methodological adaptationists even if it would be bad for the science if all investigators did so.

This chapter offers a reassessment of two familiar lines of criticism against Rawls’s Original Position (OP): the idealization critique and the fact-sensitivity critique. The former holds that the OP is too detached from the real world to deliver the right principles for us. The latter holds that the OP concedes too much to empirical reality for the resulting principles to tell us what “true justice” requires. I argue that we can blunt the force of these critiques once we fully appreciate the role that the OP plays in Rawls’s work. I distinguish between (i) Rawls’s theory, (ii) the arguments offered in support of it, and (iii) the desiderata applying to that theory, given its function. I then show that the idealization critique partly misfires, since the idealizations Rawls appeals to operate at the level of the argument offered in support of his theory, not at the level of the theory itself. Similarly, we can see that the fact-sensitivity critique does little damage to Rawls’s theory, once the theory’s function, hence the desiderata applying to it, are fully appreciated.