Agency and practical reasoning
In his “Letter on Humanism” Heidegger writes: “We are still far from pondering the essence of action decisively enough. We view action only as causing an effect” (GA 9, p. 313/239). Of action, praxis, Aristotle noted that it is something “which is itself its end” and thus cannot be understood as a cause that brings something about. Of course, action does bring things about, but that does not exhaust its meaning. It can be hard to find a way to talk about that meaning without falling into the language of causing and producing, but unless we do we shall miss Heidegger’s contribution to the philosophical elucidation of practical reason. For that contribution does not lie in explaining what makes an action rational, what it is to act according to reason; rather it lies in clarifying, phenomenologically, what it is to be an agent. For this reason, if we wish to determine where morality fits in to Heidegger’s ontology we should look not to the quality of character (virtue) or to the maxim of acts (duty) but to the nature of agency.
The concept of practical reason has roots in Aristotle’s concept of phronesis. In contrast to that sort of reason – episteme, theoria – that has to do with what “is not even capable of being otherwise” (as in mathematics or metaphysics), phronesis concerns what is “capable of being otherwise” – above all, human affairs, ethics and politics (NE 1139b, 1140b). While this way of distinguishing practical from theoretical reason has its uses, it is too bound up with the details of Aristotle’s metaphysics to be of much help in reading Heidegger. But Aristotle offers another, more salient, way of distinguishing the two. Practical reasoning, deliberation, aims to reach a decision about what to do; it pursues a chain of inference that ceases when the reasoner “has brought the moving principle back to himself and to the ruling part of himself” (NE 1113a), whereby the reasoner becomes a cause, that is, an agent.