[djcapelis]

For whatever it's worth, the 3/5ths number originally came from negotiations over modifying the original government documents of the united states: the articles of confederation where the question was whether or not slaves would count for the purposes of taxation. When the constitutional convention came around and the same debate showed up again, except now instead of taxation the question was representation, the proponents flipped positions but the 3/5ths number ended up getting picked up once again. Plus a ban on slave importation was set for 20 years in the future, which is a portion of the compromise often ignored in retrospect. (Mostly because it turned out not to be as effective as people hoped.)

The main thrust of your argument is absolutely correct though, in that the northern folks generally argued that slaves were treated as property (and so should be taxed as such) and the southern folks generally argued that they should count as people. (And should be represented as such.)

No one seemed to get to the idea that if you were going to count someone for the purposes of representation, maybe you also had to let them vote. That would have also brought up interesting questions around the disenfranchisement of various other classes of people, namely women, some white men without property and freed slaves right from the start. Instead we had to wait a long time to start solving those problems.

Politics can be weird.