Why were there witch hunts in Europe?

In the early Middle Ages, laws for much of Europe made it clear that belief in witches was a matter of superstition. The laws of the Carolingian Empire and the Kingdom of Lombardy both made killing people as witches a capital crime. Nevertheless, in other parts of Europe, the practice of prosecuting people accused as witches continued, and there were a number of executions.

In the Late Middle Ages, episcopal inquisitions were formed to investigate accusations of practice of witchcraft. But there was no systematic approach to prosecution or punishment, and there appears to have been no effort to eradicate witches proactively. Interestingly, prosecutions increased coincidentally with the beginnings of the Renaissance.

With the invention of the printing press, materials written on witchcraft began to circulate. A papal bull authorizing a systematic prosecution of witches appeared in 1484, and the result was first major book promoting witch hunts, Malleus Maleficarum, which was published in 1487 and was widely circulated.

As the interest in witch hunts increased, secular authorities, such as King James I of England and Christian IV of Denmark, began to get involved. King James I actually wrote his own book on identifying witches. Offers of bounties were made. People became expert in finding, prosecuting, and executing witches for pay. This continued through the 16th and 17th centuries, especially in Northern Europe.

The last witch trials in Europe took place in the 18th century. In 1735, the laws of England were modified to make practice of witchcraft a type of fraud, and the law was enforced as a way to harass Gypsies and spiritualists into the 20th century.