 Vander Laan explores the range of options for resolving the tension between continuous creation theory and the causal requirement. The continuous creation theorist should explain what, if not causal continuity, could distinguish a case of persistence from a case of replacement by qualitative duplicates. Of the options he considers, Vander Laan suggests that the most viable one locates the difference in a divine fiat that is present in the persistence case and absent in the replacement case (2006, 165–6). On the other hand, one who affirms the causal requirement should explain in what sense God sustains things in existence. Vander Laan identifies two possibilities: (1) a joint-sufficiency theory on which God’s causal contribution and the creature’s causal contribution are both needed for the creature’s persistence, and (2) a co-operative divine sufficiency theory on which God’s act must cause the creature to bring about its continued existence (2006, 172–4).