Generally, the guiding idea that we (or at least the properly "civilized" nations of the world) are on an unending March of Progress, onward and upward Excelsior! Manifests in several different flavors, including "Technology is the savior of humankind" (popular in the 1950s), the increase of Christian missionary work in the world, zooming GDPs, and so on. Popular with visionary capitalists, conquistadors, and politicians (on national holidays only).

Periods of its greatest currency include the Renaissance, the Age of Manifest Destiny (USA), the Age of Empire (Britain), and the 1950s. Currently rather out of fashion, having given way to the declension metanarrative--they tend to take turns.

It mostly tends to show up in stupid futurology articles where they promise us extended lifespans within the next five years and other absurdly optimistic medical and technological claims; or in patriotic speeches.