<p>A common reason for scepticism about the idea that we express any sort of free will incompatible with determinism being true (i.e. libertarian free will) has been that it wouldn’t be advantageous for us to express any kind of agency incompatible with determinism being true. Against this scepticism, I argue that we have good naturalistic reason for thinking we sometimes express this form of agency; namely—that it would be evolutionarily advantageous for us to settle matters that aren’t already settled precisely in those instances where some of what we do provides unique predictive and explanatory value. I start by examining a prevailing naturalistic theory about our origins which has contributed to this scepticism about us expressing libertarian free will. I then examine neuroscientific discoveries about neural matters underlying a pivotal expression of our rationality: decision-making. This allows me to develop my argument and discuss its implications.</p>