In philosophy, the adjective normative is used to describe statements that are based on values. A normative statement is a claim about how things ought to be. Normative statements arise most frequently in ethics.
The following are examples of normative statements:
In contrast, statements about facts that do not convey any value or moral judgements are said to be descriptive, or positive. Examples include:
Whether or not the above statements are true, they are not value-based statements.
David Hume can be credited with questioning the logical validity of normative statements. Before Hume, writers in ethics tended to derive normative statements as conclusions from sets of positive premises. Hume challenged this idea and argued that normative statements have no logical basis. This problem is known as the is-ought problem or Hume's Guillotine.
Whether or not the is-ought problem is a real problem partially hinges upon whether or not normative statements can be considered to be propositions, and thus carry a value of truth or falsity. The question of whether or not ethical-normative sentences are valid propositions is one of meta-ethics and is generally divided into cognitivism and non-cognitivism.
Normative ethics is a branch of ethics which deals with the sources of and standards for moral judgements.