The turbidity current hypothesis has met with much support as well as severe criticism. Dogmatic statements in support of this hypothesis are not uncommon in the literature and a clear distinction between fact and inference is not always made. First developed as an explanation for the origin of submarine canyons, the turbidity current hypothesis was later applied to explain the deposition of ancient flysch-type sediments as well as recent deep-sea deposits of alternating coarse and fine layers. Though a turbidity current origin for these two facies has not yet been demonstrated beyond reasonable doubt, diagnostic features of the one are commonly used to prove such an origin for the other. Such circular reasoning is unwarranted and data from both facies should be kept strictly separated. Evidence to support the turbidity current hypothesis comes from three areas: ancient flysch-type sediments; Recent deep-sea deposits; and experimental turbidity currents. Careful study of this evidence shows so many exceptions, irregularities, and inconsistencies in the general turbidity current concept, that serious doubt as to its general validity must be expressed. More consideration should be given to alternative theories, such as ocean bottom currents and tectonically controlled sedimentation. The ocean bottom current theory provides a good explanation for Recent deep-sea sedimentation, but cannot explain flysch-type deposits. Tectonically controlled sedimentation under relatively shallow water conditions provides a promising working hypothesis for the origin of flysch-type sediments.