Descriptive statements are superior to normative statement. A descriptive statement or proposition is of the form “A is X”. A normative statement is of the form “A should be X”. Descriptive statements say something about the way things are and normative statements say something about the way things should be. All normative statements are based on descriptive statements and this is why I say that descriptive statements are superior.
Take for example the normative statement “You should frequently change the oil in your car”. This is based on the descriptive statements “You want your car to function well”, “You want your car to last a long time”, “You do not want your car to be expensive to maintain” and statements like “Cars run well when they have clean oil” and so on. The normative statement “You should frequently change the oil of your car” is only true if you actually want your car to run well. If you do not then the correct normative statement would be “You should never change the oil in your car”.
The main spring of a normative statement is preference. So really normative statements are true or false depending on the preferences of the person who it is aimed at. Descriptive statements on the other hand are true or false independently of the preferences of the person who states them or the person to whom they are said. A ball is spherical independent of our tastes concerning shape. A ball should be spherical is only true if you prefer spherical balls. This is another reason why I say descriptive statements are superior to normative statements because they have an independence of subjects. Or at least they seem to.