There was never a set of principles defining manifest destiny therefore Manifest Destiny was always a general idea rather than a specific policy made with a motto. Ill-defined but keenly felt, manifest destiny was an expression of conviction in the morality and value of expansionism that complemented other popular ideas of the era, including American exceptionalism and Romantic nationalism. Andrew Jackson, who spoke of "extending the area of freedom", typified the conflation of America's potential greatness, the nation's budding sense of Romantic self-identity, and its expansion.[8][9]
Yet Jackson would not be the only president to elaborate on the principles underlying manifest destiny. Owing in part to the lack of a definitive narrative outlining its rationale, proponents offered divergent or seemingly conflicting viewpoints. While many writers focused primarily upon American expansionism, be it into Mexico or across the Pacific, others saw the term as a call to example. Without an agreed upon interpretation, much less an elaborated political philosophy, these conflicting views of America's destiny were never resolved. This variety of possible meanings was summed up by Ernest Lee Tuveson, who writes:
A vast complex of ideas, policies, and actions is comprehended under the phrase "Manifest Destiny". They are not, as we should expect, all compatible, nor do they come from any one source.[10]