Although scarcely a subject of controversy, the Monroe Doctrine, after its promulgation in 1823, remained vulnerable to disagreement over its meaning. For realists, the Monroe Doctrine represented a fundamental interest in preserving the nation's unique position as the predominant force in the hemisphere. As such, it was a policy rendered effective by the realities of power and interest in the Atlantic world. So realistic, indeed, was American purpose in preventing the establishment of rival power in the Western Hemisphere that the United States required neither war nor the threat of war to protect this essential interest. British leaders tended to accept the Monroe Doctrine as a statement of policy and nothing more.
Idealists viewed the Monroe Doctrine as a broad declaration of liberal principles. For them, the United States, in defying the Holy Alliance, had promoted less the nation's interests than the liberty of Latin America. Because the doctrine appeared to attach American purpose to a universal democratic ideal, many European masters of Realpolitik viewed it as purely utopian. They condemned it because, as a body of abstract principle, it would overreach actual U.S. economic and security interests, as well as seek to diminish European influence in Latin American affairs, solely on claims to superior political virtue. For Prince Metternich of Austria, such suppositions were nothing less than sheer arrogance. "The United States of America," he complained, "have cast blame and scorn on the institutions of Europe most worthy of respect…. In permitting themselves these unprovoked attacks, in fostering revolutions wherever they show themselves, in regretting those which have failed, in extending a helping hand to those which seem to prosper, they lend new strength to the apostles of sedition and reanimate the courage of every conspirator." In practice, every administration from Monroe to John Tyler recognized the Monroe Doctrine as policy, not principle. They accepted changes in the region, such as the British seizure of the Falkland Islands in 1833, because they did not endanger U.S. economic or security interests.
In 1845, President James K. Polk provided John C. Calhoun, at the time one of the nation's stellar realists, an opportunity to read the country a lesson on the Monroe Doctrine. During the summer of 1845, the president received reports of British designs on California. In June, François Guizot, in a speech before the French Chamber of Deputies, claimed a European interest in preserving "the balance of the Great Powers among which America is divided." In his December message to Congress, Polk, under pressure from American expansionists, repeated Monroe's declaration on noncolonization. On 14 January 1846, Senator William Allen of Ohio, chairman of the Senate Committee on Foreign Relations, introduced a resolution designed to commit Congress to the principles of the Monroe Doctrine as repeated by the president. Senator Lewis Cass of Michigan led the enthusiastic response of Democratic expansionists.
Calhoun challenged the resolution as a dangerous commitment; it seemed to invoke U.S. guardianship for all New World states against foreign aggression. If this be settled policy that was intended to have meaning, Calhoun warned, the country must concentrate its energies to carry out the policy. For Calhoun, policy required that the ends of policy be determined not by rhetoric, but by the means that the country intended to use. For him, the country had no intention of acting. Thus, Calhoun advised the Senate that it was
the part of wisdom to select wise ends in a wise manner. No wise man, with a full understanding of the subject, would pledge himself, by declaration, to do that which was beyond the power of execution, and without mature reflection as to the consequences. There would be no dignity in it. True dignity consists in making no declaration which we are not prepared to maintain. If we make the declaration, we ought to be prepared to carry it into effect against all opposition.
Cass, in another exchange with Calhoun, argued that the United States could enunciate principles without assuming any obligation to act on them. "Will mere vaporing bravado," Calhoun replied, "have any practical effect?" Effective policy, if resistance seemed proper, Calhoun asserted, required armies, navies, powerful revenues, and a determination to act. Declarations of principle would achieve nothing except to needlessly antagonize countries normally well disposed to the United States. The Senate returned the Allen resolution to committee—from which it never reemerged.
In April 1848, President Polk inaugurated the most searching examination of the Monroe Doctrine and its relevance to U.S. foreign policy in the nation's history. That month an agent of the Yucatán government, Don Justo Sierra, appealed to Polk for military aid against the rebellious Indians of the Mexican interior who threatened to drive the whites into the sea. He offered the United States, in return for its support, "dominion and sovereignty" over the state of Yucatán, adding that the same appeal had been extended to England and Spain. On 19 April, Polk, in his message to Congress, repeated his earlier sweeping assertion that it was the settled policy of the United States "that no future European colony or dominion shall…be planted or established on any part of the American continent." Polk anchored his appeal for U.S. involvement in Yucatán on both the moral obligation to rescue its white inhabitants and to prevent the possible reduction of the region to the status of a European colony. The Senate Committee on Foreign Relations quickly reported a bill to provide for an American military occupation of Yucatán. Democratic nationalists rushed to the defense of the president's request.
Again it was left for Calhoun, in a major speech of his long career, to dispose of the president's appeal to the Monroe Doctrine by demonstrating historically that the doctrine had no relevance to the Yucatán question. As a member of Monroe's cabinet in 1823, Calhoun reminded the Senate that Monroe's message was directed at one specific threat to Latin American independence—the Holy Alliance. That alliance's disintegration rendered the doctrine meaningless. Then Calhoun turned to the Monroe Doctrine as policy. In response to the president's insistence that Monroe's declarations were the settled policy of the United States, Calhoun retorted: "Declarations are not policy and cannot become settled policy." Then he asked, "Has there been one instance in which these declarations have been carried into effect? If there be, let it be pointed out." Control of Yucatán, declared Calhoun, would add nothing to the protection of Cuba or U.S. commerce in the Gulf of Mexico. For Mexico, U.S. intervention in Yucatán would be a breach of faith. Mere occupancy would resolve nothing, and without some resolution, would either collapse or become permanent. Fortunately, a sudden, unanticipated agreement between the Yucatán contestants terminated the question of U.S. intervention.