Normative scienceIn the applied sciences, normative science is a type of information that is developed, presented, or interpreted based on an assumed, usually unstated, preference for a particular outcome, policy or class of policies or outcomes. Regular or traditional science does not presuppose a policy preference, but normative science, by definition, does. Common examples of such policy preferences are arguments that pristine ecosystems are preferable to human altered ones, that native species are preferable to nonnative species, and that higher biodiversity is preferable to lower biodiversity.
Is–ought problemThe is–ought problem, as articulated by the Scottish philosopher and historian David Hume, arises when one makes claims about what ought to be that are based solely on statements about what is. Hume found that there seems to be a significant difference between descriptive or positive statements (about what is) and prescriptive or normative statements (about what ought to be), and that it is not obvious how one can coherently transition from descriptive statements to prescriptive ones.
NormativityNormative generally means relating to an evaluative standard. Normativity is the phenomenon in human societies of designating some actions or outcomes as good, desirable, or permissible, and others as bad, undesirable, or impermissible. A norm in this sense means a standard for evaluating or making judgments about behavior or outcomes. "Normative" is sometimes also used, somewhat confusingly, to mean relating to a descriptive standard: doing what is normally done or what most others are expected to do in practice.