It's well known that most of the "founding fathers" - men like Washington and Jefferson - were slaveholders. But we should not assume that the vast and disgraceful contradiction between the ideals of liberty and the practice of slavery went unnoticed in revolutionary America. As the African-American poet Phyllis Wheatley noted, it didn't take a philosopher to see that there was something wrong with this picture. And Thomas Paine, himself a working-class Englishmen bitterly opposed to hereditary privilege, began his activist career as an abolition spokesman.
Paine's Common Sense focuses on the arguments for dissolution of ties with the Crown. He does not buy the argument that Britain will "protect" America, noting that Britain "would have defended Turkey from the same motive, viz. for trade and dominion."
He also rejects the argument of England as the ancestral home of the Americans, noting that only about one-third of the Colonial population are of English descent (the rest coming from other parts of Europe). "But, admitting [i.e., even if it were the case] that we are all of English descent, what does it amount to? Nothing."
The son of a Quaker, Paine held humanitarian ideals in the highest regard; but he himself was no pacifist. The following passage is worth quoting in full:
To talk of friendship with those in whom our reason forbids us to have faith, and our afections wounded through a thousand pores instruct us to detest, is madness and folly. Every day wears out the little remains of kindred between us and them; and can there be any reason to hope, that as the relationship expires, the affection will increase, or that we shall agree better when we have ten times more and greater concerns to quarrel over than ever?
Ye that tell us of harmony and reconciliation, can ye restore to us the time that is past? ...
But Paine's quarrel was with the English regime, not with the English people. After his fortunes failed in the post-Revolution era, he returned to England, where (the Norton Anthology informs us) "he wrote his second and most successful work, The Rights of Man". It's important to note that this work was not a Colonial manifesto like Common Sense, but "an impassioned plea against hereditary monarchy" (Norton) - that is, a call for democratic reform in England and France. In short, he was attempting to export the American Revolution.