By Allen C. Guelzo, Ph.D., Gettysburg College
In 1783, to levy assessments on the states, the Confederation Congress switched the assessment basis from wealth to population, counting slaves as only three-fifths of a person. When this matter came up for discussion during the Constitutional Convention, Rufus King, Gouverneur Morris, and Luther Martin, among others, opposed the very concept of slavery.

Slavery and Assessments on the States
No state legislature gave any of its delegations to the Constitutional Convention any directives on what to do about slavery, and the issue seemed, for quite long in the Convention, to have been peripheral to what the delegates thought they were doing.
The Articles of Confederation were originally supposed to levy assessments on the states based upon wealth, according to the value of the real estate of each. But in 1783, the difficulties of making this sort of determination moved the Confederation Congress to switch the assessment basis to population, taking care to count slaves as only three-fifths of a person, and counting all “white and other free citizens and inhabitants, of every age, sex and condition, including those bound to servitude for a term of years” as whole—or, so to speak, five-fifths of a person.
This is a transcript from the video series America’s Founding Fathers. Watch it now, on Wondrium.
The Three-fifth Rule and Taxation
This three-fifths stipulation had actually nothing to do with representation; it was about taxation.
The Articles of Confederation had of course fixed representation in Congress at one vote for each state. Nor did the Convention spend much time on the subject of slavery for the first two months of its sittings. As soon as the subject of proportional representation surfaced, there was serious grumbling about whether slaves should be included in the base population of inhabitants used for determining each state’s number of representatives, and the three-fifths formula from the Articles of Confederation was trotted out as a pacifier.
The Committee on Detail hoped it could be made to work again as a pacifier, but they had not reckoned with Rufus King.
Concerns of Rufus King
Rufus King was not a moralist; he did not particularly like slavery. The admission of slaves was a most grating circumstance to his mind, and he believed would be so to a great part of the people of America.
But his primary concern was whether the counting of slaves among American inhabitants for determining representation in Congress, even if the slaves were only counted as three-fifths of a person for determining that representation, might give an incentive to slave owners to import more slaves.
King was sure that the people of the northern states could never be reconciled to it, at least not without some national prohibition in the new Constitution on the importation of slaves. He could never agree to let them be imported without limitation and then be represented in the National Legislature.
Learn more about Benjamin Franklin and slavery in America.
Gouverneur Morris

Gouverneur Morris moved to insert the word “free” before the word “inhabitants” in describing the formula for determining representation—free inhabitants. In other words, no-fifths of the slaves would be counted for the purposes of representation.
Unlike King, Morris’s rationale for such an amendment rasped directly across the dissonance of slavery and liberty. Morris said he would never concur in upholding domestic slavery.
Needless to say, Morris’s motion to insert “free” in front of “inhabitants” went down to a resounding defeat. Only New Jersey’s delegates voted in the favor.
Objections by Luther Martin
But if the slave owners in the Convention hoped that Morris’s eruption was going to be only an isolated moment, they reckoned without the formidable, vulgar Luther Martin.
Although Martin was himself the owner of six slaves, he saw better than most in the Convention that, without some alteration, the Committee of Detail’s report was going to end up granting the larger slave states an untoward edge in the deliberations of the new Congress.
Since “five slaves are to be counted as three free men in the apportionment of Representatives,” and since, he said, “such a clause would leave an encouragement to” the importation of more and more slaves, the solution, Martin announced was “to allow a prohibition or tax on the importation of slaves.”
Learn more about Charles Pinckney’s Counterrevolution.
The Southern State Delegations
South Carolina’s John Rutledge, the chair of the Committee of Detail, was on his feet at once with a violent riposte to Martin. Rutledge did not see how the importation of slaves could be encouraged by the three-fifths rule. But what galled him most were the toplofty moralisms he had heard from the other critics.
If the Convention wanted to fool around with prohibiting slave imports, or even taxing them, then the question would become “whether the Southern States shall or shall not be parties to the Union.”
For Charles Cotesworth Pinckney, it was entirely a matter of economic survival. He believed that in South Carolina, the nature of the climate, and the flat, swampy situation of the country, obliged the people to cultivate the lands with slaves, and that without them South Carolina would soon be a desert waste.
Roger Sherman assured John Rutledge that while he disapproved of the slave trade, he thought it best to leave the matter as was found since slavery was dying out on its own.
Common Questions about Slavery and Liberty: The Critical Debate during the Constitutional Convention
Rufus King’s primary concern was that counting slaves as even three-fifths of a person for determining representation might give an incentive to slave owners to import more slaves.
Luther Martin believed that counting slaves as three-fifths of a person might encourage importation of more slaves, so the solution was to allow a prohibition or tax on the importation of slaves.
Charles Cotesworth Pinckney believed that slaves were necessary for economic survival. He believed that in South Carolina, the nature of the climate, and the flat, swampy situation of the country, obliged the people to cultivate the lands with slaves, and that without them South Carolina would soon be a desert waste.