A fundamentally timeless world implied by quantum gravity threatens a recent model offered for mechanistically justified phenomenological laws described by Gabriel Siegel and C. Craver. The criteria for these laws appear to collapse when met with thermal time, a physical theory compatible with weak timelessness. I argue that this collapse hinges on the theory of emergence used to define mechanistic explanation under thermal time. Two cases of emergence are examined——one reductionist, one pluralist——revealing that both erase the distinction between etiological and relevant constitutive explanation. However, only the reductionist perspective diminishes the explanatory power of phenomenological laws as determined by Siegel and Craver. The other preserves this power. I examine the intersection between interventionist mechanism, timelessness, and emergence within the authors’ framework to support these conclusions by performing a thought experiment using propositional logic and set theory. This analysis discusses the implications of timelessness, principally its threat to mechanistically justified phenomenological laws and how its emergence shapes the sufficiency of mechanistic explanations.