The term
Gnosticism is used by scholars with a wide variety of meanings and levels of specificity. Sometimes the term refers only to those
Sethians who used the term
gnostikoi to describe themselves. Sometimes it is used more broadly to include
Valentinians, followers of
Basilides, and others. Likewise, one scholar may consider
Simon Magus a gnostic, where another considers him a proto-gnostic. Some early Church fathers, such as
Irenaeus, seemed to think that all
heresies were Gnosticism at root, and thus that any heretic was in a sense a Gnostic.