In Kant's regularity model of causality, overdetermination is a genuine option: different, equally legitimate causal accounts can be offered of the same event. So it is possible for some human behavior to be both determined by natural necessity and free. That it be free means that it is rational, and the possibility of rational behavior cannot be excluded, though its reality can never be proved for substantive reasons. Judging a behavior to be rational requires adopting an attitude toward it that abstracts from its spatiotemporal coordinates, and hence, losing all means of identification.
Keywords: freedom, causality, rationality, spatiotemporal