A rationalist argument for libertarian free will

In this thesis, I give an a priori argument in defense of libertarian free will. I conclude that given certain presuppositions, the ability to do otherwise is a necessary requirement for substantive rationality; the ability to think and act in light of reasons. ‘Transcendental’ arguments to the effect that determinism is inconsistent with rationality are predominantly forwarded in a Kantian manner. Their incorporation into the framework of critical philosophy renders the ontological status of their claims problematic; rather than being claims about how the world really is, they end up being claims about how the mind must conceive of it. To make their ontological status more secure, I provide a rationalist framework that turns them from claims about how the mind must view the world into claims about the ontology of rational agents. In the first chapter, I make some preliminary remarks about reason, reasons and rationality and argue that an agent’s access to alternative possibilities is a necessary condition for being under the scope of normative reasons. In the second chapter, I motivate rationalism about a priori justification. In the third chapter, I present the rationalist argument for libertarian free will and defend it against objections. Several objections rest on a compatibilist understanding of an agent’s abilities. To undercut them, I devote the fourth chapter, in which I give a new argument for incompatibilism between free will and determinism, which I call the situatedness argument for incompatibilism. If the presuppositions of the thesis are granted and the situatedness argument works, then we may be justified in thinking that to the extent that we are substantively rational, we are free in the libertarian sense.