Abstract
The core argument in favor of the view that immorality is a natural defect for human beings, which has been developed by Foot, assumes that if justice and compassion have important functions in human survival and reproduction, then injustice and cruelty are natural defects in human beings. But this ignores possibilities and results that cannot reasonably be ignored. Multiple and mixed naturally sound types can and do occur in nature. Moreover, research in the life sciences suggests that at least some bad human behaviors, traits, or strategies are selected for and continue to have important survival-and-reproduction-related functions in human life. All this fits poorly with the position that immorality is a natural defect for human beings. Emerging as much more plausible is the competing view that, for human beings, natural soundness sometimes supports behaviors, traits, or strategies that conflict with (any ideal that can plausibly be called) moral goodness.