In her essay concerning the Three-Fifths Clause, "The Three-Fifths Clause and the Origins of Sectionalism" (in Finkelman and Kennon (eds.), Congress and the Emergence of Sectionalism), Jan Lewis correctly points out that it was James Wilson of Pennsylvania who first proposed at the Philadelphia Convention that the Federal Ratio be applied to the allocation of representives.
Prof. Lewis expresses surprise that Wilson did so, and that he did so at such an early stage of the proceedings (on June 11, 1787). The Confederation Congress had proposed in 1783 that the Federal Ratio be used to allocate state contributions to the general treasury. But "no one had ever suggested that slaves be included in the basis for calculating representatives." And no "delegates, at least in public, [had yet] said the first thing about slavery. The word had not yet even been mentioned."
I have a different take. I would submit that the idea of the Three-Fifths Clause was present from the opening days of the Philadelphia Convention, when Edmund Randolph introduced the so-called Virginia Plan.
On May 29, 1787, Edmund Randolph of Virginia presented to the Convention his famous Plan, consisting of fourteen resolutions that were, he said, designed to "correct & enlarge" the Articles of Confederation so "as to accomplish the objects proposed by their institution; namely, 'common defence, security of liberty and general welfare.'"
The second of Randolph's resolutions addressed the allocation of representatives to the "National Legislature." The third, fourth and fifth resolutions proposed that the "National Legislature" be a bicameral institution. I therefore quote them all:
2. Resd. therefore that the rights of suffrage in the National Legislature ought to be proportioned to the Quotas of contribution, or to the number of free inhabitants, as the one or the other rule may seem best in different cases.
3. Resd. that the National Legislature ought to consist of two branches.
4. Resd. that the members of the first branch of the National Legislature ought to be elected by the people of the several States every ----- for the term of -----; to be of the age of ----- years at least, to receive liberal stipends by with they may be compensated for the devotion of their time to public service; to be ineligible to any office established by a particular State, or under the authority of the United States, except those peculiarly belonging to the functions of the first branch, during the term of service, and for the space of ----- after its expiration; to be incapable of reelection for the space of ----- after the expiration of their term of service, and to be subject to recall.
5. Resold. that the members of the second branch of the National Legislature ought to be elected by those of the first, out of a proper number of persons nominated by the individual Legislatures, to be of the age of ----- years at least; to hold their offices for a term sufficient to ensure their independency; to receive liberal stipends, by which they may be compensated for the devotion of their time to public service; and to be ineligible to any office established by a particular State, or under the authority of the United States, except those peculiarly belonging to the functions of the second branch, during the term of service, and for the space of ----- after the expiration thereof.
Taken together, these resolutions proposed that the "first branch of the National Legislature" should "be elected by the people of the several states". The number of representatives allocated to each state should be "proportioned to the Quotas of contribution, or to the number of free inhabitants."
The members of the first branch would then elect the members of the "second branch" from nominees submitted by the "individual [state] Legislatures." Again, allocation of seats in the "second branch" among the states would "be proportioned to the Quotas of contribution, or to the number of free inhabitants."
For my purposes, the crucial language is that concerning allocation. Randolph proposed two options, applicable to both branches of the legislature "as the one or the other rule may seem best in different cases."
The second "rule" or option was perfectly clear: seats might be proportioned according to "the number of free inhabitants."
But the first option, I would argue, was also clear: "Quotas of contribution" referred to the surrogates developed to estimate the wealth of the various states - either the real property valuation scheme set forth in Article VIII of the Articles of Confederation, or the population-based formula set forth in the amendment to that Article proposed by the Confederation Congress in 1783. (See my earlier post, The Origins of the Three-Fifths Clause.)
And the population-based formula, as everyone at the Convention knew perfectly well, came with its own ready-made sub-formula for calculating the value of slave labor.
In fact, I would go further. The Confederation Congress - including many of the men attending the Philadelphia Convention - had determined that the property-based valuation scheme was unworkable. That left the population-based formula. Is it not fair to say that Randolph's alternatives realistically boiled down to allocation (a) based on free population, or (b) based the total population, with a discount for slaves (the Federal Ratio)?
Ironically, Prof. Lewis's own essay confirms that the answer is in the affirmative. "[E]veryone in the room [at the Philadelphia Convention] knew the congressional formula for calculating 'quota of contribution.'" When South Carolina delegates later advocated that option, "[t]hey knew, even if they did not state so explicitly, that 'quota of contribution' came, courtesy of the [Confederation] Congress, with a ready-made formula: all the free people plus three-fifths of the slaves."
I believe that Prof. Lewis's conclusion that "everyone knew" is correct. But if that is true, then Edmund Randolph, James Madison and the rest of the Virginia delegation understood that they were proposing an apportionment choice between "free inhabitants" and "all inhabitants, counting three-fifths of slaves." And the other delegates understood that those were the options that Randolph and the Virginians were proposing.
No one may have mentioned the words "slavery" or "three-fifths" at the Convention until James Wilson did so on June 11. But both were on the table, I believe, from the moment Edmund Randolph laid out his second resolution on May 29.