An indefinitely mutable term, changing as our scientific conception of the world changes, and often best seen as signifying a contrast with something considered not part of nature. The term applies both to individual species (it is the nature of gold to be dense or of dogs to be friendly), and also to the natural world as a whole. The sense in which it applies to species quickly links up with ethical and aesthetic ideals: a thing ought to realize its nature; what is natural is what it is good for a thing to become; it is natural for humans to be healthy or two-legged, and departure from this is a misfortune or deformity. The association of what is natural with what it is good to become is visible in Plato, and is the central idea of Aristotle’s philosophy of nature. Unfortunately the pinnacle of nature in this sense is the mature adult male citizen, with the rest of what we would call the natural world, including women, slaves, children, and other species, not quite making it.

Nature in general can, however, function as a foil to any ideal as much as a source of ideals: in this sense fallen nature is contrasted with a supposed celestial realization of the forms. The Galilean world view might have been expected to drain nature of its ethical content, but the term seldom loses its normative force, and the belief in universal natural laws provided its own set of ideals. In the 18th century, for example, a painter or writer could be praised as natural, where the qualities expected would include normal (‘universal’) topics treated with simplicity, economy, regularity, and harmony. Later on, nature becomes an equally potent emblem of irregularity, wildness, and fertile diversity, but also associated with progress and transformation (see absolute idealism, Romanticism). Contrasts with nature may include

1. (i) that which is deformed or grotesque, or fails to achieve its proper form or function, or just the statistically uncommon or unfamiliar;

2. (ii) the supernatural, or the world of gods and invisible agencies;

3. (iii) the world of rationality and intelligence, conceived of as distinct from the biological and physical order;

4. (iv) that which is manufactured and artificial, or the product of human intervention;

5. (v) related to that, the world of convention and artifice.

Different conceptions of nature continue to have ethical overtones: for example, the conception of ‘nature red in tooth and claw’ often provides a justification for aggressive personal and political relations, or the idea that it is women’s nature to be one thing or another is taken to be a justification for differential social expectations. Here the term functions as a fig-leaf for a particular set of stereotypes, and is a proper target of much feminist writing. See also Darwinism, environmental ethics, natural law, Naturphilosophie, neurosexism, sociobiology.