Here then, are those provisions of the Constitution, which the most extravagant defenders of slavery can claim to guarantee a right of property in man. These are the provisions which have been pressed into the service of the human fleshmongers of America. Let us look at them just as they stand, one by one. Let us grant, for the sake of the argument, that the first of these provisions, referring to the basis of representation and taxation, does refer to slaves. We are not compelled to make that admission, for it might fairly apply to aliens — persons living in the country, but not naturalized. But giving the provisions the very worse construction, what does it amount to? I answer — It is a downright disability laid upon the slaveholding States; one which deprives those States of two-fifths of their natural basis of representation. A black man in a free State is worth just two-fifths more than a black man in a slave State, as a basis of political power under the Constitution. Therefore, instead of encouraging slavery, the Constitution encourages freedom by giving an increase of “two-fifths” of political power to free over slave States. So much for the three-fifths clause; taking it at is worst, it still leans to freedom, not slavery; for, be it remembered that the Constitution nowhere forbids a coloured man to vote.
Frederick Douglass, March 26, 1860