In the context of the moral realism vs. moral subjectivism and theism vs. atheism debates the question of moral semantics is often raised: How do we define goodness?  Some are under the mistaken impression that if we cannot define goodness (a question of moral semantics) then we cannot claim to know goodness exists (a question of moral ontology) or identify what is good (a question of moral epistemology).  

I do not want to focus on whether it is possible to provide an adequate account of moral semantics, but rather to point out that even if we are unable to do so, it does not follow that there are no objective moral goods or that we are incapable of knowing them.  Greg Koukl illustrates this point beautifully.  He notes how our experience of goodness is similar to our experience of color.  We recognize color as color when we see it.  If someone were to ask us how we know what green is, we would respond, “I just see it.”  We don’t need to define green to know it when we encounter it.  Similarly, we do not need to define goodness to know that we have encountered it.  God has given us moral intuitions to recognize good and discern between good and evil. 

All of us have a basic moral intuition that recognizes the existence of a realm of objective moral values, just as we have sensory intuitions that apprehend a realm of physical objects.  As atheistic philosopher Louise Anthony said in her debate with William Craig, “Any argument for moral skepticism will based upon premises which are less obvious than the existence of objective moral values themselves.”  When we behold good and evil, we simply recognize them for what they are. 

The way we “see” goodness is not the way we see a giraffe, but the way we see the truth of a syllogism.  If Socrates is a man, and all men are mortal, then it follows that Socrates is mortal.  You don’t see the truth of that conclusion with your physical senses, but with your logical intuitions.  Similarly, we recognize what is good through our moral intuitions.  No definition is required.