What is the Muslim academic Jonathan A. C. Brown's opinion on slavery?

In a Nutshell: Jonathan Brown believes today slavery is wrong and argues Islam prohibits it, based on the consensus of the ulama. States are permitted to prohibit what was previously allowed if doing so serves some public interest (maslaha). Background Jonathan Brown, is a tenured Georgetown professor and holder of the Al-Waleed bin Talal Chair in Islamic Civilization at Georgetown University, delivering his lecture on slavery here and penning his article here. He argues slavery under Islam was quite different to chattel slavery seen in the Americas, because of significant difference in rights, being something "social," rather than "economic." Given Muhammed held slaves, it cannot be argued as unethical. Regarding concubines, female sex slaves imprisoned in a harem, he correctly argues we can't judge past civilizations by contemporary sexual standards, as we view people as autonomous agents, their consent making a sexual act acceptable. "For most of human history, human beings have not thought of consent as the essential feature of morally correct sexual activity. And second, we fetishise the idea of autonomy to where we forget, who is really free? … What does autonomy mean?" Brown goes on to argue Muslims began curtailing slavery early on. In the 1000s, the great Persian scholar Juwayni gave a fatwa that slave girls captured in Central Asia should not be sold as concubines. In the 1780s, the scholar-king of Senegal Abd al-Qadir Kan abolished slavery in his realm and banned the French from slave trading there, preceding the beginning of organized abolition in Britain, with early abolitionists citing Kan as a model ruler. In 1846, before Lincoln's emancipation proclamation, Ahmad Bey, the governor of Tunis, banned the slave trade there and emancipated all slaves in his realm. By 1900, many leading Muslim scholars had agreed that slavery should be prohibited. As Muslim states signed treaties banning slavery in the early twentieth century, the practice all but disappeared. A crucial point is slavery isn't one thing. It has varied dramatically across time and space, from the horrors of racist, inhuman chattel slavery on the plantations of the American South to mukataba in the Ottoman Empire. Mukataba was an emancipation contract for a fixed time and with rights to own property and marry; it was closer to being a wageworker in a 19th-century British factory than what we think of as American slavery.  In the Islamic world, slaves actually ruled entire states. The ruling dynasty of one empire, the Mamluks, was all slaves. The administrative and military elite of the Ottoman Empire, the most powerful and richest people in the realm, were technically slaves of the Sultan. Islamic ethics regarding slavery In the Qur'an and Sunnah, the only avenue left for slavery was dealing with people who had been captured in war. All other forms were outright abolished. The Prophet (saw) guaranteed them appropriate food, clothing, shelter and no overly taxing labor. They could be disciplined no more harshly than one's own kids. The Qur'an instructed owners to make mukataba agreements with slaves if they were fit and able to make it on their own and Muslim scholars understood that it was better to keep those who were otherwise too old or unable to fend for themselves as slaves rather than setting them free to starve. The Qur'an and Sunnah made clear over and over that freeing slaves was one of the best deeds a Muslim could do. The Shari'a saw freedom as the natural state (asl) of all humans. And, as the legal maxim stated, the Shari'a "aimed towards freedom." As Muslims spread out across the globe and new peoples and cultures entered the faith, existing traditions of slavery took on an Islamic veneer. Sometimes the humane values of the Shari'a prevailed. Sometimes local customs and systems of exploitation continued, moderated only a little by God's law. Slavery in Islam was never tied to one race, but in certain times and places it could become racialized, as happened with the prevalence of black African slaves in Egypt in the 1700s-1800s. Slavery of some sort has existed in almost every human society since the dawn of time. Moses, Jesus, the Buddha, Aristotle and Plato all considered the slavery in their times to be accepted features of life. Islam considered slavery, even in its restricted form, to be an 'incapacity', an injustice (zulm), as the Muslim jurist Shaybani called it around the year 800 CE.  But it was an economic and social condition and it was usually temporary. As economic life changed in the 1800s, Muslim societies saw this institution could be eliminated. The Egyptian scholar Muhammed Abu Zahra summed it up: Islam would welcome a day when slavery was banned. Conclusion As a Muslim today, he says slavery is wrong and Islam prohibits it. This has been the consensus of the ulama and it's well within the power of states to prohibit what was previously allowed if doing so serves some public interest (maslaha) - known as taqyid al-mubah (restricting the permitted). Whilst easy to say looking back on slavery in American history, because American slavery was a manifestation of the absolute domination of one human being by another, a universal wrong across time and space.