Ohhhhhh boy. I think most of the "founding fathers" had slaves. I'm not saying that justifies it, but put into historical context, they probably thought of slaves as less than human, so their philosophical ideas didn't apply to slaves. It's terrible, I know. Similarly, in the UK, there was a man who was part of the NSPCC, an anti-child abuse organization, who turned out to have abused children. Hypocrisy like that exists throughout history.
The entire Athens Democracy was built on slavery as were the Spanish and English Empires and the young US nation. That is the human condition: Rights are limited. By class, social group, wealth, power and race and gender. Still today though slavery is not as common any more than it used to be. Looking to Africa and Asia and some other areas slavery is still an operational part of economy and we all benefit from it as the world market sells those goods everywhere.
I'm sure it's common for people's stock investments not to totally reflect their moral values. You're just trying to make a buck, such things are regarded on a merely functionalistic level, and your measly 1200 or whatever shares will never made a large difference toward the activities of the company. In fact, they'll never make any difference at all, since your owning that stock doesn't give the company itself any new money. The only difference it could make is via your shareholder's voting rights, and that could only have only worked toward Locke's values, as it means more power for him to make the company do--or not do--what he wanted.
Or: Maybe early liberalism only cared about freedom for white people? Similarly to how I heard that Steven Pinker is a utilitarian who is anti-vegan and pro animal exploitation, presumably because he doesn't believe animal happiness and suffering count toward the overall level of collective good. Also similarly to how right in the constitution it said "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness," yet somehow that wasn't considered to apply to black people.
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