Other hugely influential British writers followed in Smith’s wake, with William Paley mocking slavery in Moral Philosophy (1785), which was widely circulated as a textbook:
But necessity is pretended; the name under which every enormity is attempted to be justified. And after all, what is the necessity? It has never been proved that the land could not be cultivated there, as it is here, by hired servants. It is said, that it could not be cultivated with quite the same conveniency and cheapness, as by the labour of slaves; by which means, a pound of sugar, which the planter now sells for sixpence could not be afforded under sixpence halfpenny; – and this is the necessity!43
The views of such figures as Smith and Paley are of huge significance since they meant, in more modern terms, that the intellectual attack on slavery came from the right as well as the left; it was not necessary to believe in an entirely new social order or in inalienable rights of man in order to accept that slavery could not be economically justified or pragmatically accepted. For young, conservative-minded British politicians such as Pitt and Wilberforce, the works of Adam Smith and William Paley were high on their list of reading materials.
The changing intellectual climate of the late eighteenth century helped to awaken a Christian concern about slavery which had occasionally surfaced in earlier centuries, to little effect. Vatican rulings against the keeping of slaves in the seventeenth century had been understood to refer to natives of the Americas rather than to African Negroes, and the call for ‘an end to slavery’ by Pope Clement XI early in the eighteenth century was greeted with total indifference in Lisbon and Madrid. Yet while established Churches, whether in Rome or Canterbury, were too politically constrained and philosophically complacent to mount a serious challenge to such a widely accepted institution as slavery, the subject was a natural one for Christians of a more reforming or Evangelical disposition. As early as 1671 George Fox, the founder of the Quakers, had called on slave-owners not to use cruelty towards Negroes, and ‘that after certain years of servitude they should set them free’.44 By the late eighteenth century, as the scale and growth of slavery became more widely acknowledged and the moral climate of the times moved against it, it became a natural target for Evangelicals and Methodists. Moreover, their beliefs in applying Christian principles to the whole of life, in the importance of Providence and their accountability to God, gave many of them a sense of unavoidable responsibility to combat slavery, rather than a choice of whether or not to do so. By 1774 John Wesley was railing against the slave trade and all who took part in it, threatening slave traders with a worse fate than Sodom and Gomorrah and reminding them that ‘He shall have Judgment without mercy that hath showed no mercy.’ He told plantation-owners that ‘Men-buyers are exactly on a level with Men-stealers,’ and merchants that their money was being used ‘to steal, rob, murder men, women and children without number’; ‘Liberty is the right of every human creature, as soon as he breathes the vital air. And no human law can deprive him of that right, which he derives from the law of nature.’45 It was on the basis of such thinking that in due course British Evangelicals would eventually become an indispensable component of the campaign against the slave trade.
It was, however, the Quakers who would lead the way in setting out the Christian case against slavery and the slave trade, bringing to bear an influence far beyond their numbers, partly because they included highly active and respected individuals, and partly because they constituted a genuinely transatlantic community. The Quakers included many influential traders and merchants, and when the annual meeting of the Society of Friends in Philadelphia in 1754 came to the conclusion that ‘to live in ease and plenty by the toil of those who violence and cruelty have put in our power’ was incompatible with Christianity, it was a decision of more than token significance.46 The decisions of the Philadelphia Society of Friends led within a short time to their London counterparts coming to the same conclusion. Similarly, when the Quaker Anthony Benezet’s anti-slave-trade tract Observations on the Enslaving, Importing, and Purchasing of Negroes was published in America in the 1760s the London Quakers responded by ordering 1,500 copies and distributing them to every member of both Houses of Parliament. Benezet’s powerful arguments against slavery not only rested on Christian principles but were wholly in tune with Enlightenment ideas: ‘Nothing,’ he wrote in 1767, ‘can more clearly and positively militate against the slavery of the Negroes than the several declarations lately published that “all men are created equal, that they are endowed by their creator with certain unalienable rights.”’47
The arguments of the Quakers were one of several powerful forces at work in North America in the 1760s and 1770s which would contribute to opening up the debate over the slave trade in Britain. A second factor was the growing fear in some of the North American colonies that the continued importation of large numbers of slaves would create an uncontrollable population prone to revolution in the future. In the words of Benjamin Franklin, ‘Slaves rather weaken than strengthen the State, and there is therefore some difference between them and sheep; sheep will never make insurrections.’48 This concern led some states, such as New Jersey in 1769, to impose a prohibitive level of duty on the import of slaves. Once the American Revolution was underway, the second Continental Congress passed a resolution opposing slave imports in 1776, and many of the northern states went on to act against slavery itself – Pennsylvania, for instance, passed a law in 1780 ensuring that all future born slaves would become free at the age of twenty-eight. Within a year of the end of the American War of Independence, all of the New England states had made legal provision for the abolition of slavery on their territory.
The British reaction to the American Revolution was a third factor which may have helped to inculcate the idea that the institution of slavery was no longer immutable. While Samuel Johnson taunted the Americans with the question, ‘How is it that we hear the loudest yelps for liberty among the drivers of Negroes?’,49 British generals seeking every possible weapon to use against the colonists made extensive promises of freedom to slaves held in North America. In 1775 the Governor of Virginia, the Earl of Dunmore, offered freedom to all slaves who would bear arms against the rebellion: the subsequent years of war saw tens of thousands of slaves desert their owners, and some of them did indeed serve alongside the British Army. Sometimes the population of entire plantations managed to run away, with some states losing over half their slaves. At the end of the war, these desertions would leave the defeated British with the problem of what to do with large numbers of former slaves who had come under their protection, many of them congregated in still-loyal New York, with the eventual result that thousands of them would be unsatisfactorily resettled in Nova Scotia.
One of the effects of the American Revolution was, therefore, to create a significant free black population in the nascent United States, but it also left behind it a sharp political disagreement over the future of slavery and the slave trade, which would divide the United States and influence debate in the rest of the English-speaking world. While northern states responded to American Independence by emancipating slaves, southern states, which were much more heavily economically dependent on slave labour, responded to the end of the war with a surge of slave imports to make up for the large numbers of deserters. Within a remarkably short time the future battle lines of the American Civil War of eighty years later were drawn, facilitated by the historic compromise at the constitutional convention which declared that: ‘The importation of such persons as any of the States now existing shall think proper to admit, shall not be prohibited prior to the year eighteen hundred and eight.’50 The future President James Madison would defend the compromise as ‘a great point gained in favour of humanity, that a period of twenty years may terminate forever within these States a traffic which is so long and so loudly upbraided as the barbarism of modern policy’,51 but the result was that the period from 1787 to 1807 saw more slaves sold into the United States than any other two decades in history. By the end of the century, opinion in the southern states had turned firmly against the anti-slavery assumptions of the Founding Fathers, and abolitionist sentiment was once again largely confined to the ranks of the valiant Quakers.
In the meantime, Quaker campaigners such as Anthony Benezet had been discovering useful allies across the Atlantic. In his work specifically directed at a British audience A Caution and Warning to Great Britain and her Colonies (1766), Benezet asked British Christians: