Summis desiderantes affectibus

Summis desiderantes affectibus (Latin for "desiring with supreme ardor"), sometimes abbreviated to Summis desiderantes, was a papal bull regarding witchcraft issued by Pope Innocent VIII on 5 December 1484.

Belief in witchcraft is ancient. Deuteronomy 18:11–12 in the Hebrew Bible states: "Let there not be found among you anyone who immolates his son or daughter in the fire, nor a fortune-teller, soothsayer, charmer, diviner, or caster of spells, nor one who consults ghosts and spirits or seeks oracles from the dead."

Pope Gregory VII wrote to Harald III of Denmark in 1080 forbidding witches to be put to death upon presumption of their having caused storms or failure of crops or pestilence. According to Herbert Thurston, the fierce denunciation and persecution of supposed sorceresses which characterized the witchhunts of a later age, were not generally found in the first thirteen hundred years of the Christian era.

According to historians such as Martin Del Rio and P.G. Maxwell-Stuart, "The early Church had set out the distinctions between white and black magic... The penalties were restricted to confession, repentance, and charitable work".

The bull was written in response to the request of Dominican Inquisitor Heinrich Kramer for explicit authority to prosecute witchcraft in Germany, after he was refused assistance by the local ecclesiastical authorities, who maintained that as the letter of deputation did not specifically mention where the inquisitors may operate, they could not legally exercise their functions in their areas. The bull sought to remedy this jurisdictional dispute by specifically identifying the dioceses of Mainz, Cologne, Trier, Salzburg, and Bremen.

Innocent's Bull enacted nothing new. Its direct purport was to ratify the powers already conferred upon Kramer (also known as "Henry Institoris") and James Sprenger to deal with witchcraft as well as heresy, and it called upon the Bishop of Strasburg (then Albert of Palatinate-Mosbach) to lend the inquisitors all possible support. Some scholars view the bull as "clearly political", motivated by jurisdictional disputes between the local German Catholic priests and clerics from the Office of the Inquisition who answered more directly to the pope.

The bull recognized the existence of witches:

Many persons of both sexes, unmindful of their own salvation and straying from the Catholic Faith, have abandoned themselves to devils, incubi and succubi, and by their incantations, spells, conjurations, and other accursed charms and crafts, enormities and horrid offences, have slain infants yet in the mother's womb, as also the offspring of cattle, have blasted the produce of the earth, the grapes of the vine, the fruits of the trees, nay, men and women, beasts of burthen, herd-beasts, as well as animals of other kinds, vineyards, orchards, meadows, pasture-land, corn, wheat, and all other cereals; these wretches furthermore afflict and torment men and women, beasts of burthen, herd-beasts, as well as animals of other kinds, with terrible and piteous pains and sore diseases, both internal and external; they hinder men from performing the sexual act and women from conceiving ... they blasphemously renounce that Faith which is theirs by the Sacrament of Baptism, and at the instigation of the Enemy of Mankind they do not shrink from committing and perpetrating the foulest abominations and filthiest excesses to the deadly peril of their own souls ... the abominations and enormities in question remain unpunished not without open danger to the souls of many and peril of eternal damnation.