 This specific cyclic theory has been challenged, and other cyclic cosmological theories have been proposed. What this shows is that any attempt to support the second premise of the kalām argument by accepting or refuting scientific cosmologies will encounter an ever-changing scene, given the speculative nature of cosmology. Thus, while Craig and Sinclair (2009: 150–74) critically evaluate current contenders as not being viable, changes in and development of these theories and the inevitable development of others make for unending point-counterpoint. 