The twenty-first century has brought forth a deluge of theories and data shedding light on the neural mechanisms of motivated behavior. Much of this progress has focused on dopaminergic dynamics, including their signaling properties (how do they vary with expectations and outcomes?) and their downstream impacts in target regions (how do they affect learning and behavior?). In parallel, the basal ganglia have been elevated from their original implication in motoric function to a canonical circuit facilitating the initiation, invigoration, and selection of actions across levels of abstraction, from motor to cognitive operations. This review considers how striatal D1 and D2 opponency allows animals to perform cost-benefit calculations across multiple scales: locally, whether to select a given action, and globally, whether to engage a particular corticostriatal circuit for guiding behavior. An emerging understanding of such functions reconciles seemingly conflicting data and has implications for neuroscience, psychology, behavioral economics, and artificial intelligence.