It is fallacious to confuse necessity and possibility. Modal logic deals with the logic of possibility as well as necessity. This was, however, a matter of political choice rather than legal necessity. Moreover, this was a kind of knowledge associated with people who were bound to necessity. International circumstances made the referendum a growing necessity. And opinions are characterized by a lack of necessity and stability. Modalities of necessity and possibility are called "alethic" modalities. Debate continues over the necessity, significance and effect of the battle. His judgment is contingent and holds no necessity. Materials used depended on the wealth, climate, and necessity. Although doubts existed about the military necessity of a major uprising, planning continued. This is also accepted as an everyday necessity. Luxemburg professed a commitment to democracy and the necessity of revolution. Lincoln cancelled the illegal proclamation as politically motivated and lacking military necessity. The metaphysical structures of necessity and contingency are different.