set a proposition as asserted or questioned). Another purported feature of norms, it is often argued, is that they never regard only natural properties or entities. Norms always bring something artificial, conventional, institutional or "unworldly". This might be related to Hume's assertion that it is not possible to derive ought from is and to G.E. Moore's claim that there is a naturalistic fallacy when one tries to analyse "good" and "bad" in terms of a natural concept. In aesthetics, it has also been argued that it is impossible to derive an aesthetical predicate from a non-aesthetical one. The acceptability of non-natural properties, however, is strongly debated in present-day philosophy. Some authors deny their existence, some others try to reduce them to natural ones, on which the former supervene. Other thinkers (Adler, 1986) assert that norms can be natural in a different sense than that of "corresponding to something proceeding from the object of the prescription as a strictly internal source of action". Rather, those who assert the existence of natural prescriptions say norms can suit a natural need on the part of the prescribed entity. More to the point, however, is the putting forward of the notion that just as descriptive statements being considered true are conditioned upon certain self-evident descriptive truths suiting the nature of reality (such as: it is impossible for the same thing to be and not be at the same time and in the same manner), a prescriptive truth can suit the nature of the will through the authority of it being based upon self-evident prescriptive truths (such as: one ought to desire what is really good for one and nothing else). Recent works maintain that normativity has an important role in several different philosophical subjects, not only in ethics and philosophy of law (see Dancy, 2000). See also Constitution Deontic logic Deontology Law (principle) Meta-ethics Norm (sociology) Normative Normative ethics Normative statement Philosophy of law Principle Law Rule of law Rule according to higher law Social norm Speech act Further reading Adler, Mortimer (1985), Ten Philosophical Mistakes, MacMillan, New York. Aglo, John (1998), Norme et symbole: les fondements philosophiques de l'obligation, L'Harmattan, Paris. Aglo, John (2001), Les fondements philosophiques de la morale dans une société à tradition orale, L'Harmattan, Paris. Alexy, Robert (1985), Theorie der Grundrechte, Suhrkamp, Frankfurt a. M.. Translation: A Theory of Constitutional Rights, Oxford University Press, Oxford: 2002. Bicchieri, Cristina (2006), The