Emergency Powers Let the President Borrow
Constitutions of civil government are not to be framed upon a calculation of existing exigencies, but upon a combination of these with the probable exigencies of ages, according to the natural and tried course of human affairs. Nothing, therefore, can be more fallacious than to infer the extent of any power, proper to be lodged in the national government, from an estimate of its immediate necessities. There ought to be a capacity to provide for future contingencies as they may happen; and as these are illimitable in their nature, it is impossible safely to limit that capacity. - Hamilton in the Federalist Papers
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Hamilton, like Locke and others before him, believed that ultimately the executive in a liberal constitutional system must have a power sometimes, called the prerogative to act unilaterally to address serious unanticipated threats to public well-being.
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Whichever view you accept, it provides a basis for President Obama to raise the debt ceiling on his own if he believes with good reason that the failure to raise the debt ceiling would lead to default on U.S. debt, and that this in turn would lead to the collapse of the financial system and economic depression. Default is not a legitimate policy choice; no one favors it. It would result from a failure of our institutions, not from a compromise among contending political groups, and the presidents intervention would surely be ratified by the public and even by Congress.
The contrary view that the president must sit helplessly as the economy collapses, fettered by a reading of an 18th-century document that not even the founders would have believed appropriate reflects a legalistic mentality that none of our great presidents has possessed or acted on.
http://www.nytimes.com/roomfordebate/2013/10/02/can-obama-ignore-the-debt-ceiling/emergency-powers-let-the-president-borrow-beyond-the-debt-limit