The normalized, deterministic conception of evolution espoused by Dennett is increasingly being challenged by theorists who, following Gould, emphasize the role that historical contingencies play in it. I explore the conflict between these views and argue that correcting our understanding of the relationship between nature’s systematic necessities and historical temporality can resolve it. The mathematically precise laws science formulates describe the systematic patterns of nature abstractly and, as abstractions, these laws do not preclude but allow for the contingencies of historical time. Drawing on Heidegger and Hume, I argue that historical time is characterized by the ingression of the unprecedented future into the present. This is the ontological infrastructure that makes the evolution of unprecedented ontological alterities possible.