One of the most interesting contrasts are his thoughts on Slavery. In 1772, when Ben Franklin was forty-two years old, he bought a few slaves, and was given one as a payment of debt. Prior to this he had defended the Colonies use of them, as can be witnessed in his "A Conversation on Slavery" as printed in The Public Advertiser, January 30, 1770. In this he compares the colonies use of slaves to the English working poor ('Your working Poor are not indeed absolutely Slaves; but there seems something a little like Slavery'), the Scottish coal miners ('All the Wretches that dig Coal for you, in those dark Caverns under Ground, unblessed by Sunshine, are absolute Slaves by your Law, and their Children after them') and the English sailors that are forced into service ('The Sailor is often forced into Service, torn from all his natural Connections'). His point in this conversation is more to point out the British brutality than justify slavery, but it does both. His publications, including the Pennsylvania Gazette even printed runaway slave and slave sale notices.
But as early as 1775 you begin to see a change as he exchanges many letters with David Hartley about the need for Abolition and a weening of the Colonies from it's 'vice of slavery'. In 1778 he successfully passed a bill through the Virginia legislature for the banning of future slave importation to Virginia. He also authored a 1784 proposal to the Continental Congress that would’ve abolished slavery in the Northwestern Territory that failed to pass by a single vote. In 1789 he was elected the president of the Society for Promoting the Abolition of Slavery. Franklin formulated a gradual abolition plan that featured an end to the slave trade, the prohibition of slavery in all the western territories and the establishment of a fixed date after which all newly born children of slaves would be emancipated. Unfortunately he was never able to get this accepted.
Despite all this, unlike Washington and other founding fathers, he did not free his slaves. Perhaps it is due to his financial situation in the 1780s or he just could not overcome the 'vice' himself. Either way, it should not detract from his great accomplishments, nor his desire to improve our society.