1.  Strong belief that Satan is acting in the world.
---------"The invisible world": disease, natural catastophes, and bad fortune attributed to work of the devil
2.  A belief that Satan recruits witches and wizards to work for him.
---------Prior witchcraft cases in New England (and Europe before)
3.  A belief that a person afflicted by witchcraft exhibits certain symptoms.
---------Cotton Mather's Memorable Providences
---------Most symptoms can be feigned
4.  A time  of troubles, making it seem likely that Satan was active.
---------Smallpox
---------Congregational strife in Salem Village
---------Frontier wars with Indians
5.  Stimulation of imaginations by Tituba.
6.   Convulsive ergotism, a disease caused by eating infecting rye that can produce hallucinations, causing strange behavior?  (Interesting theory, but unlikely.)
7.  Teenage boredom.
---------No television, no CDs, and lots of Bible reading
---------Strict and humorless Parris household
8.  Magistrates and judges receptive to accusations of witchcraft.
---------See as way to shift blame for their own wartime failures
---------Admission of spectral evidence
9.  Confessing "witches" adding credibility to earlier charges.
10.  Old feuds (disputes within congregation, property disputes) between the accusers and the accused spurring charges of witchcraft.