Nolen Gertz at the Aeon online site
In moral philosophy, nihilism is seen as the denial that morality exists. As Donald A Crosby argues in The Specter of the Absurd (1988), moral nihilism can be seen as a consequence of epistemological nihilism.
Here things get tricky for me.
Until we are able to grasp an understanding of existence itself [which may not even be possible] what does it mean to speak of nihilism epistemologically? After all, in regard to what we either can or cannot know about the totality of reality itself how are we are not always back to this:
There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.
Instead, my own understanding of "moral nihilism" revolves around the distinction I make between objective knowledge derived from interactions in the either/or world and subjective/subjunctive claims of knowledge in the is/ought world. The gap between knowledge that we seem able to demonstrate as applicable to all of us and opinions embedded in our reaction to human interactions in which conflicts occur regarding behaviors deemed to be either right or wrong. The part I root in dasein.
If there exist no grounds for making objective claims about knowledge and truth, then there exist no grounds for making objective claims about right and wrong. In other words, what we take to be morality is a matter of what is believed to be right – whether that belief is relative to each historical period, to each culture or to each individual – rather than a matter of what is right.
But: As long as there are things in which objective claims of knowledge appear to be exchanged and then sustained year after year after year, where exactly is the line to be drawn between truth and opinion in regard to conflicting goods?
And each of us here is basically in the same leaky boat that has capsized philosophers going back now thousands of year. Boats filled with holes that are unable to be plugged with arguments that settle once and for all what really is the right and the wrong thing to do.
Here instead of there. Now instead of then.
Except of course in any particular philosopher's head.