A quote from J. Philippe Rushton & Arthur R. Jensen in Psychology, Public Policy, and Law (2005, Vol. 11, No. 2, 328-336) (pdf)
The naturalistic fallacy [...] occurs when reasoning jumps from statements about what is to prescription about what ought to be. An example of the naturalistic fallacy would be to support warfare if scientific evidence showed that it was to some degree part of human nature. [...] The converse of the naturalistic fallacy is the moralistic fallacy, which occurs when reasoning jumps from prescriptions about what ought to be to statements about what is. [...] An example of the moralistic fallacy is to claim that because warfare is wrong, it cannot be part of human nature.
One corollary of the moralistic fallacy is the demonizing of those who refuse to observe it. Another is that someone must be blamed whenever Nature stubbornly refuses to conform. Because Blacks and Whites ought to be equal in IQ and educational outcome but still are not, some who adopt a moralistic position hold, in effect, that White people’s attitudes are largely to blame [...]. Both fallacies are conjoined when it is argued that whereas minority dislike of Whites is “natural” (because of mistreatment, or because of feeling “culturally dominated”), White prejudice is inherently bigoted and “unnatural.”