Ben Franklin owned 3 slaves when living in Philadelphia in his youth. Just before his death, his last publication was to write a satire ridiculing slavery.

Attitudes changed at the end of the 18th century and beginning of the 19th. When the abolitionist underground movement began in 1819 or therabouts, perhaps Rev. Caldwell was a supporter, if not of abolition and manumission, at least of saving those most cruelly treated.

That would be precisely what we would expect, given what was written of his character and what we know about the evangelical Presbyterian Church to which he belonged.

Abraham Lincoln would criticize Northerners who insisted they were morally superior to the southernors who supported slavery. He said that the northernors would likely do the same, if they faced the economic scarcity of labor that afflicted the southern plantation owners. In addressing southernors, he did not condemn them as exploiters. Instead, he asked them to apply the same virtues that had led them to favor halting the expansion of slavery into the free states, and the cessation of the African slave trade.