naturalistic fallacy

noun2

1. •
   The fallacious belief that something is automatically good because it is natural or automatically bad because it is unnatural.

   • No, we do not have to put moral reasoning in a special category and use transcendental premises, because the posing of the naturalistic fallacy is itself a fallacy. For if ought is not is, what is? — 1998
2. •
   Any attempt to define "good" verbally, instead of treating it as an undefined term, in terms of which other terms are defined.