Throughout his life, Benjamin Franklin had a tendency to change his mind on political issues. For example, he initially supported the Stamp Act and only later decided that the American colonies should separate from Britain. Yet often Franklin ended up on the winning side of an argument, even if the argument was not settled in his lifetime.

Like his opinion of the American Revolution, Franklin’s views on slavery changed, too. He owned a couple of slaves at various times of his life and published ads for slave auctions when he worked as a printer. Still, he and his wife Deborah made sure that their slaves received an education from a Philadelphia school for black students. Most slave owners didn’t think slaves could learn, but after Franklin visited the school he commented that he had “higher opinions of the natural capacities of the black race.” He also published a few articles arguing against slavery. Until 1787, however, Franklin never gave the abolition of slavery his complete support.

By 1787, the year of the Constitutional Convention, Franklin became president of the Pennsylvania Society for Promoting the Abolition of Slavery. During the convention, he sought to include a statement about the freeing of slaves in the U.S. Constitution. Like many of the Founding Fathers, however, Franklin feared that the union between northern and southern states would not be created if he argued too forcefully for the end of slavery.

Franklin’s silence on the abolition of slavery lasted only until the Constitution was ratified and the new federal government was in place. In 1790, he submitted a petition on the society’s behalf to the U.S. Congress. Franklin declared that slavery contradicted the principles of the American Revolution, particularly the ideas that all men were created equal and that they were entitled to liberty. The petition stated that Congress had an obligation to ensure “the blessings of liberty to the people of the United States without distinction of color.”

The anti-slavery petition set off a heated debate in Congress. It angered pro-slavery advocates like Congressman James Jackson of Georgia. He stated that the Bible supported slavery and that slaves were needed to do the work on the South’s plantations. Though in poor health, Franklin didn’t miss the opportunity to mock Jackson’s speech in print. He compared it to a speech supposedly given one hundred years earlier by an Algerian pirate who had Christian slaves. The pirate argued that it was “in the interest of the state to continue the practice; therefore let the petition be rejected.” He also said that his religion permitted the enslavement of Christians, and that they were better off living as slaves than as free men in Europe “where they would only cut each other’s throats in religious wars.”

Like Franklin’s fictional Algerian pirate, Congress rejected the petition to end slavery. After the debate ended, George Washington wrote to a friend, “the slave business has at last [been] put to rest and will scarce awake.” The contradiction of slavery and the promises of liberty for all Americans awoke again in the nineteenth century, resulting in the Civil War. Once again, Franklin had picked the point of view that eventually prevailed.