Assume that all these countries have had different levels of exposure to slavery, meaning the total amount of GDP can be attributed to slavery, and that would b

Assume that all these countries have had different levels of exposure to slavery, meaning the total amount of GDP can be attributed to slavery, and that would be thus lost if they abolished slavery and refused to trade with companies or individuals which use slavery (e.g. place an embargo on American cotton unless it's certified). I mean, it's a fair assumption: slavery was abolished in France in 1794, in the United Kingdom in 1833 and in the United States in 1865. Germany mainly traded with it's European neighbors, which didn't use slave labor in their territories. Then how can all these different countries have similar levels of GDP per capita and similar growth paths, despite their different levels of exposure? Furthermore, there currently poor countries which relied on slave labor for much longer. Brazil only abolished slavery in 1888. Morocco, in 1922. And if we include serfdom, Russia, in 1861. Unless you mean metaphorical slavery. I grant that it would take much more sophisticated analysis in order to properly exclude any confounding factors, but that's kinda the point, really. I don't think you really thought this through.