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.