This dissertation articulates a conception of practical thought as genuinely productive. Its core thesis is that practical reason is a sui generis form of causal capacity: one whose efficacy is intrinsically rational, or equivalently, one whose rationality is intrinsically efficacious.,In the first chapter I consider the prospects for an account of genuinely productive reason through engagement with the two pioneers of 20th Century philosophy of action: Elizabeth Anscombe and Donald Davidson. I argue that Davidson was correct to think that practical thought is simultaneously rational and efficacious. However, his conception of causality forces him to pry apart the rationality of practical thought from its efficacy. Anscombe places the notion of 'practical knowledge' at the center of her account of intentional action, which she partly describes by deploying a phrase of Aquinas: practical knowledge is "the cause of what it understands". Crucially, the kind of causation at issue is formal causation. I argue that the claim that practical knowledge explains why action has the form it has, leaves hanging the question of how the form contained in the agent's knowledge is present in their action. If we are to understand how an agent's thought is actually productive of change we need to move beyond the mere idea of formal causation. We can do this, I suggest, if we understand practical reason as a causal capacity.,In Chapter Two I begin to explicate the idea that intentional action is the exercise of a causal capacity. I argue, contra many contemporary accounts, that agent's exercises of their causal capacities, i.e., their actions, are identical to the changes that agents thereby make; I offer an Aristotelian account of actions as transactions between agents and patients that is consonant with that conclusion. ,In Chapter Three I investigate the specifically rational causality of practical reason. I argue against recent attempts to explicate the rational causality of intentional action that identify practical judgments with intentional actions, on the grounds that they misconstrue both the temporal and the formal character of action. Practical reasoning has a form of its own: that of 'realizing ends'. This rational activity (i) exhibits a form of kinetic temporality proper to production, and (ii) involves a special relation between the general and the particular. Whereas judgment subsumes particulars that are existentially independent of it under general concepts, practical reasoning is the making particular of that which always starts out as inherently general, through both the specification of means and the realization of those means in action., ,In Chapter Four I explain how intentional movements can themselves be acts of practical reason. I argue that Intentional movements are the most basic form of rationality distinctive of practical reason, for in movement something inherently general (i.e., an intention) is directly made particular (i.e., materially real). To understand movement as the direct realization of ends, I give an account of agents' capacities to perform basic actions and the special role of the agent's body in action. I argue that the agent's body is not the object of a capacity for movement (like, for example, a tennis racquet) but is the embodiment of the capacity to move. In the case of my body there is no distinction between what is moved and the power to move it.,In Chapter Five, I show that the distinctive form of practical reason described in the preceding chapters demands that agents, in successful instrumental reasoning, recognize their ends as actually good. What sets the standard for instrumental reasoning is not whether a thinker brings the correct general concept to the particular reality before them, but whether they have made real the general end they are seeking to realize. Such ends, I argue, are not objects of theoretical reason, but a form of practical generality. Consequently, there is no answer as to whether one action genuinely realizes another that can be given simply in terms of knowledge about, for example, the kinds of causal relations that hold between events and/or objects. Since the very idea of realizing an end through means involves a standard for success that cannot be grounded in theoretical thought, it necessarily depends on an irreducibly practical standard contained in the agent's knowledge of their end as good. Only a good end can contain a standard against which the realization of ends is more or less successful. Ultimately the productivity of practical reason consists in its being the capacity to realize the good. The efficacy of practical reason can, therefore, be described as the efficacy of the good.