The Principle of Doubt is the third album by the German progressive / thrash metal band Mekong Delta, released in 1989.

[3] The album is loosely based on Stephen R. Donaldson's dark fantasy trilogy, The Chronicles of Thomas Covenant, the Unbeliever.

[4] All music composed by Ralph Hubert, except where indicated.

Lyrics by Mekong Delta.

Arrangements for group and orchestra of track 6 by Mekong Delta, arrangements for drum and bass of track 9 by Michael and Hubert.