For the 19th century liberal and historian of ideas William Lecky, the most striking fact about England and France in the 17th century was the decline of belief in the supernatural. And the most striking instance of this fact was the collapse of belief in witchcraft.

At the beginning of that century, belief in witchcraft had been universal and unchallenged. James VI of Scotland (1567-1625) was one of the most learned men of his day. He believed without question in witches, and was a notable persecutor. When he became King of England as well in 1603, he brought his policies with him. It was to gain favour with him that Shakespeare introduced the witchcraft theme into Macbeth.

James procured a law that punished witchcraft with death on first conviction, even though no harm to others could be proven. This law was carried in a Parliament where Francis Bacon was a Member.

The law was carried into effect throughout England, and was especially used during the interregnum years of the 1650s. In 1664, under the restored Monarchy, Sir Matthew Hale — one of the greatest jurists and legal philosophers of the age — presided over the trial of two alleged witches in Suffolk. He told the jury that there could be no doubt in the reality of witchcraft. He said:

For first, the Scriptures had affirmed so much; and secondly, the wisdom of all nations had provided laws against such persons, which is an argument for their confidence of such a crime.

One of the witnesses called for the prosecution was Sir Thomas Browne, one of the most notable writers of the age. Appearing as a medical expert, he assured the jury “that he was clearly of opinion that the persons were bewitched.” They were convicted and hanged.

It was the same in France. In the town of St Claude, 600 persons were burnt in the early years of the century for alleged witchcraft and lycanthropy. In 1643, Cardinal Mazarin wrote to a bishop to congratulate him on his zeal for hunting out witches.

Yet, in 1667, Colbert, the chief minister of Louis XIV, directed all the magistrates in France to receive no more accusations of witchcraft. Those convictions still obtained he frequently commuted from death to banishment. By the end of the century, witchcraft trials had all but ceased.

In England, belief collapsed later, but even faster than in France. The last trial for witchcraft was in 1712. Jane Wenham, an old woman, was accused of the usual offences. The judge mocked the prosecution witnesses from the bench. When the jury convicted her against his directions, he made sure to obtain a royal pardon for the old woman and a pension.

Whatever the lowest reaches of the common people might still believe, belief in witchcraft had become a joke among the educated. And because of the tone they gave to the whole of society, disbelief spread rapidly beyond the educated. Anyone who tried to maintain its existence was simply laughed at. Laws that had condemned tens or hundreds of thousands to death, and usually to the most revolting tortures before death, were now sneered into abeyance.

We should expect that a change of opinion so immense had been accompanied by a long debate — something similar to the debates of the 19th century over Darwinism, or to the debates of the day over the toleration of nonconformity. Yet Lecky maintains that there was almost no debate worth mentioning. There were sceptics, like Montaigne, who disbelieved all accounts of the supernatural, or Hobbes, who was a materialist and atheist. But, while, book after book appeared in England during the late 17th century to defend the existence of witches and the need for laws against them, almost no one bothered to argue that witches did not exist. Lecky says:

Several… divines came forward…; and they made witchcraft, for a time, one of the chief subjects of controversy. On the other side, the discussion was extremely languid. No writer, comparable in ability to Glanvil, More, Cudworth, or even Casaubon, appeared to challenge the belief; nor did any of the writings on that side obtain any success at all equal to that of [Glanvil].

Belief in witchcraft perished with hardly a direct blow against it. What seems to have happened, Lecky argues, is a change of world view in which belief in witches ceased to have any explanatory value. We live in a world where, orthodox religion aside, belief in the supernatural is confined to the uneducated or the stupid or the insane. But if we step outside the consensus in which we live, we should see that there is nothing in itself irrational about belief in the supernatural, nor even in witches. The belief is perfectly rational granted certain assumptions.

Let us assume that the world is filled with invisible and very powerful beings, that some of these are good and some evil, that some human beings are capable of establishing contact with these evil beings, and that some compact can be made in which the power of the evil beings is transferred to human control. Granting these assumptions, it becomes reasonable to ascribe great or unusual events to magical intervention, and that it should be the purpose of the law to check such intervention.

Now, the Platonic philosophies do accept the existence of such beings. That is how Plato reconciled his One Creator with the many gods of the Greek pantheon. This belief was taken over by the Church Fathers, who simply announced that the ancient gods were demons. It then continued into the 17th century. It seemed to explain the world. Doubtless, cases came to light of false accusations and of people convicted because they were ill rather than possessed by demons. But our own awareness of corrupt policemen and false convictions does not lead us to believe that there are no murderers and that murder should not be punished. So it was with witchcraft.

During the 17th century, however, the educated classes came increasingly to believe that the world operated according to known, impersonal laws, and that God — assuming His Existence — seldom interfered with the working of these secondary laws. In such a view of the world, the supernatural had no place. Belief in witchcraft, therefore, did not need opposition. It perished as collateral damage to the system of which it was a part.

Sean Gabb, “Epicurus: Father of the Enlightenment”, speaking to the 6/20 Club in London, 2007-09-06.