The debate soon broadened out far beyond the lines of the original scheme, and in it the student finds lucidly presented the issues of public policy that have accompanied tariff debates ever since.
Madison laid down the general principle that "commerce ought to be free, and labor and industry left at large to find its proper object," but suggested that it would be unwise to apply this principle without regard to particular circumstances.

"Although interest will, in general, operate effectually to produce political good, yet there are causes in which certain factitious circumstances may divert it from its natural channel, or throw or retain it in an artificial one." In language which now reads like prophecy he referred to cases "where cities, companies, or opulent individuals engross the business from others, by having had an uninterrupted possession of it, or by the extent of their capitals being able to destroy a competition." The same situation could occur between nations, and had to be considered.

There was some truth, he also thought, in the opinion "that each nation should have within itself the means of defense, independent of foreign supplies," but he considered that this argument had been urged beyond reason, as "there is good reason to believe that, when it becomes necessary, we may obtain supplies abroad as readily as any other nation whatsoever." He instanced as a cogent reason in favor of protective duties that, as the States had formerly the power of making regulations of trade to cherish their domestic interests, it must be presumed that, when they put the exercise of this power into other hands by adopting the Constitution, "they must have done this with the expectation that those interests would not be neglected" by Congress.
Actuated by such views, and doubtless also influenced by the great need for revenue, Madison was on the whole favorable to amendments extending the list of dutiable articles.

Though there were conflicts between members from manufacturing districts and those from agricultural constituencies, and though the salt protectionists of New York had some difficulty in carrying their point, the contention did not follow sectional lines.

Coal was added to the list on the motion of a member from Virginia.