The Federalist, Alexander Hamilton and James Madison's serialized defence of the new U.S. Constitution drafted at Philadelphia that summer, would have had little difficulty convincing its readers of the decrepitude into which the republic had sunk in 1787.

An impotent federal government, unable to make its laws apply or to raise revenues without leave from the states; paralysis on important national questions, without the required unanimity among the states; a multiplication of barriers to trade between the states, such that ''we may reasonably expect . . . that the citizens of each would at length come to be considered . . . by the others in no better light than that of foreigners.'' Sound familiar?

Then as now, however, while all could agree on the failure of confederation, much dispute attended the remedy. There were, then as now, advocates for breaking the union into three or four smaller confederacies; there were also, then as now, advocates for a strengthened union, like the Federalist; and there were, then as now, advocates for something in between, for whom the Federalist reserved special contempt:

''They seem still to aim at things repugnant and irreconcilable; at an augmentation of federal authority, without a diminution of state authority; at sovereignty in the union, and complete independence in the members.'' That hoary Yvon Deschamps joke about an independent Quebec in a united Canada is older than we know.

The chief advantage of federalism, for the authors, consisted in the establishment of a government at one remove from local passions and parochial politics. In particular, ''the enlargement of the orbit'' in which government revolved would help to ward off the dangers of ''faction,'' what today we would call interest groups, ''the mortal disease under which popular governments have everywhere perished.''

''The influence of factious leaders may kindle a flame within their particular states, but will be unable to spread a general conflagration through the other states,'' the Federalist pointed out. ''A rage for paper money, for an abolition of debts, for an equal division of property, or for any other improper or wicked project, will be less apt to pervade the whole body of the union than a particular member of it.''

Moderated by its volume, as a lake is less easily disturbed than a pond, a federation is also less prone to the tyranny of the majority, or the fury of the moment. For example, ''not a single Indian war has yet been occasioned by the aggressions of the present federal government . . . but there are several instances of Indian hostilities having been provoked by the improper conduct of individual states.'' Yes indeed.

A second major advantage lay in the preservation of a single market, not only for its own sake, but for the leverage it provided in international trade talks. ''Would it not enable us to negotiate, with the fairest prospect of success for commercial privileges of the most valuable and extensive kind?'' Further, a successful bilateral deal ''would be likely to have a correspondent effect on the conduct of other nations, who would not be inclined to see themselves altogether supplanted in our trade.''

A larger market, moreover, since it diversifies exports, improves a nation's trade position. ''The variety, not less than the value, of products for exportation contributes to the activity of foreign commerce.'' Whereas a region or province is hostage to the boom-and-bust cycle of one commodity, in a federation, when the terms of trade move against one good, another compensates.

The Federalist warned against the delusion of thinking a common market could be preserved in the event of deconfederation. ''A unity of commercial, as well as political, interests, can only result from a unity of government.'' There could be no economic union without political union; no sovereignty with association.

Without a ''general discretionary superintendence,'' the separate states will be ''alternate friends and enemies of each other, as our mutual jealousies and rivalships . . . should prescribe to us.'' There would be disputes over unclaimed territory, and over ''the apportionment, in the first instance, and the progressive extinguishment'' of the public debt.

The choice was clear: to establish ''a strict and indissoluble union'' or to split into ''an infinity of little, jealous, clashing, tumultuous commonwealths, the wretched nurseries of unceasing discord, and the miserable objects of universal pity or contempt.'' It is the same today. Upon the dissolution of the union, Canada, like the U.S., ''will have reason to exclaim, in the words of the poet: 'FAREWELL!  A LONG FAREWELL TO ALL MY GREATNESS.' ''