Fact–value distinction

The fact-value distinction is a distinction between what is (can be discovered by science, philosophy, or reason) and what ought to be (a judgment agreed to by consensus, or believed to be objectively morally binding). The terms positive and normative represent another way to express this, as do the terms descriptive and prescriptive, respectively. Positive statements make the implicit claim to facts (e.g., water molecules are made of two hydrogen atoms and one oxygen atom), whereas normative statements make a claim based on values or norms (e.g., water ought to be protected from pollution).