by Patrick Appel
The three-fifths compromise was, from a purely practical perspective, a positive inasmuch as it weakened the South relative to the North. But it was hugely negative from an ideological perspective because it established in America’s founding document that slaves were not analogous to women and children that they were something less than full (nonvoting) members of the community. Cattle, free children and slaves all could not vote. Cattle had no representation, free children had full representation, and slaves had partial representation. That’s a pretty perfect expression of the ideology of white supremacy that was a necessary component of the slave system as practiced in the United States. Which is precisely what it is understood to be today, and precisely why it is considered so offensive in retrospect.
I've updated the title of this post, which was originally accidentally entitled "Why Three Fifths Was Better Than Nothing." The original Millman post, which appears to be unaccessible because the American Scene's server is down, very clearly argued that it would have been better for slaves to not be counted at all or counted fully. Since readers are unable to read Millman's full argument, I'll quote another section:
Had slaves been granted zero weight for apportionment purposes, that would have weakened the South practically and would plainly have said that slaves are not in a condition analogous to women and children full human beings who are nonetheless dependent on other human beings for, among other things, representation. That would, obviously, have been optimal from an anti-slavery perspective.
Had slaves been granted full weight for apportionment purposes, that would have strengthened the South practically, which would have been very negative from an anti-slavery perspective. But it would also have implied that slaves were, indeed, analogous to women and children fully human, but dependent on others because of their condition. This was the official ideology of the slave power, but essential features of the slave system most notably the fact that slaves were not merely owned but traded, which made normal family life among slaves a legal impossibility were always incompatible with any true recognition that slaves were fully human. Any such formal recognition, then, would be an ideological victory against slavery.