When we use words like morality, good, virtue and just we believe we are getting at ought claims which I argue we cannot ground or establish as certain knowledge. However, I do think these words can continue to be used in the fashion that Schopenhauer uses them, and to express this I will use the analogy of the Hero. It is my claim that we cannot ground ought-claims in pure reason. We cannot know for certain what ought to be or be done if anything. Heroism, if being a hero requires doing what one ought to do, becomes problematic then. This problem evaporates however if we take a purely descriptive account of virtue and heroism.
If a hero is defined instead as merely someone who saves lives, regardless of whether or not a life should be saved, then one can use the word regardless of whether or not we know we ought to save life generally speaking or not. I use the word “generally” because I acknowledge there are debatable cases where some will claim a genuine hero will not save someone – whether or not Superman should save Lex Luther or Batman save the Joker for example. This is the exception and not the rule however. We can slightly alter the definition but it remains that the hero is one who does heroic things, regardless of whether or not he ought to and regardless of the details of what heroism really is.
In essence, we can do what Socrates is known for in much of Plato’s dialogue and inquire upon the true nature of temperance or virtue, we can give descriptive accounts of its origin in humans and give accounts of its use in language; all of which are entirely sufficient in descriptive use and accounts of being with no normativity being introduced. To summarize, we can say that chocolate is “good” as long as our understanding of good in this context is completely removed from the notion that humans ought to consume chocolate or chocolate ought to exist. We can give a descriptive accounts of traits we describe as virtuous, their sources, motivations and so on while not arguing that we ought to be virtuous.