John Holbo at Crooked Timber and Jillian at Sadly, No! (among others) have done excellent work eviscerating Michael Medved's mind-numbingly stupid and morally bankrupt historical revisionism on slavery--in particular, this passage:
3. THOUGH BRUTAL, SLAVERY WASN’T GENOCIDAL: LIVE SLAVES WERE VALUABLE BUT DEAD CAPTIVES BROUGHT NO PROFIT. Historians agree that hundreds of thousands, and probably millions of slaves perished over the course of 300 years during the rigors of the “Middle Passage” across the Atlantic Ocean. Perhaps the most horrifying aspect of these voyages involves the fact that no slave traders wanted to see this level of deadly suffering: they benefited only from delivering (and selling) live slaves, not from tossing corpses into the ocean.But while most have commented on the inverted morality of this (the passage is ambiguous, but only as far as the particular immorality; there is no interpretation that is in any way defensible), on second reading it's even more wrong in more ways than it seemed at first.
Medved is arguing (I think) that the slave traders cannot be blamed for those deaths because they had every economic incentive to keep their slaves alive. In fact, this is the exact opposite of reality: those slaves died because their lives were worth less than other economic incentives. It would have cost more to run more ships with fewer slaves on each. It would have cost more to feed them adequately. The supply of human cargo was plentiful enough that it was more economical for the slavers to pack their ships beyond the limits of human endurance and let half of them die than to make the effort to get them all there alive. The economic incentives Medved tries to cite as a mitigating factor are the very things that motivated the (yes) genocide.
Medved, of course, is a cheerleader for the Free! Market!, the sort of cheerleader who sees it as inherently and always a force for Good and simply cannot conceive of supply and demand as forces that ever lead to monstrous results. Hence the twisted lunatic rationalizations he comes up with to argue that the market is never to blame.