[lordnacho]

Why would learning stuff require a deal with the devil? Two of the listed demons are described pretty much as what a scientist is.

If you find a proof of P != NP or the Riemann hypothesis, why would that be as bad as using the Death Note book?

[drdec]

The demons are just trying to satisfy the marketplace. They provide whatever will sell.

[lordnacho]

Surely there would be more demons in the vanity/jealousy/revenge market than the knowledge market?

[krapp]

There are many more demons to choose from than the ones listed in the article[0].

The interesting thing about demonology is that it was mostly being practiced in secret by Christians, even clergy (a lot of these spells and rituals use Christian liturgical elements.) They didn't believe what they were doing was "selling their soul to the devil," rather that Christ had given them dominion over angels and demons, so they had every right to summon demons and use them as they saw fit. Legend at the time was that King Solomon built the First Temple using demon slaves.

Of course the Church proper would have strenuously agreed with this way of thinking.

[0]https://en.wikipedia.org/wiki/List_of_demons_in_the_Ars_Goet...

[krapp]

There was no such thing as "science" at the time - every aspect of human thought and philosophy had some religious dimension or spiritual connotation. The study of the stars and planets was tied to astrology, and the study of herbs and healing was associated with witchcraft and folk magic.