The initial observation that gene order was highly conserved over large evolutionary distances, for example, between passerines and galliformes, was shown to be only partially true once higher density maps with sufficient resolution to detect minor within-chromosome rearrangements became available (Backström et al., 2006; Stapley et al., 2008; Backström et al., 2010).
The philosopher of science Karl Popper devoted his intellectual life to the theory of falsificationism, the idea that a hypothesis can only be proved true once it is shown it can be false.
And, of course, this sort of view yields the prediction that non-explicitly relativized "good" sentences — including those used throughout moral philosophy — are really only true or false once the end parameter is specified, perhaps by context.
What was once "the only true test of Alpine skiing," as its founder said in 1969, is now the staging ground where fierce individual and ski club rivalries play out.
The museum was the brainchild of the charismatic mayor of Guetaria, a hilly Basque fishing village near San Sebastián, and it was to be a magnificent tribute to the man Coco Chanel once called the only "true couturier".
Once George Washington, the only true national hero of the era, passed from the scene, most delegates believed that no single candidate would ever be sufficiently well-known throughout the country to get a majority of the electoral vote and that the contest would always wind up in the House of Representatives.
In religious terms, think of this as a loss of confidence among the military priesthood in what had once been the Only True Faith, and a fear that "thinking the unthinkable" -- as it was called in the nuclear arsenal's Cold War heyday -- might someday actually become unthinkable.
It may have been true once that expertise in computer science was needed only by computer scientists.
True once, true always, you might say.
That might have been true once.
