Aristotle's Nicomachean Ethics presents a compelling argument for a distinct human function, one that forms the bedrock of his understanding of the good life. Rather than a mere biological or mechanical purpose, Aristotle posits that the unique human function lies in the exercise of our rational soul. This function, when performed excellently, leads to eudaimonia, often translated as flourishing or living well. To argue that humans possess such a function is to suggest that there is a telos, or end, for human existence, and that understanding this telos is crucial for ethical living and achieving the highest good.
The initial step in Aristotle's reasoning is to identify what makes humans distinct from other living things. He observes that all living entities, from plants to animals, have characteristic activities: plants grow and nourish themselves, while animals possess sensation and locomotion. Humans, however, share these capacities with other organisms. What sets us apart, according to Aristotle, is our capacity for logos – reason. This includes the ability to deliberate, to understand abstract concepts, and to act in accordance with rational principles. Therefore, the function of a human being, distinguishing us from the rest, must involve the activity of the soul in accordance with reason.
However, simply possessing reason is not sufficient for fulfilling this function. The function argument emphasizes not just the possession of a capacity, but its excellence in performance. A good lyre player is not merely one who can play a lyre, but one who plays it well. Similarly, a good human being is one who exercises their rational capacities well. This excellence in performance, Aristotle argues, is virtue (aretē). Virtues are not innate qualities; they are cultivated through habituation and practice. For example, courage is developed by repeatedly facing and overcoming fears, and temperance by consistently moderating desires. These virtues, both intellectual and moral, allow us to act rationally and appropriately in various life situations.
The ultimate aim of performing this function excellently is eudaimonia. This state is not a fleeting feeling of happiness or a mere accumulation of external goods. Instead, it is a sustained condition of living well and doing well, a complete life lived in accordance with virtue. Aristotle elaborates that eudaimonia is the most desirable of all things, being an end in itself and not pursued for the sake of something else. While external goods like health, wealth, and friends are often necessary preconditions or facilitators of a flourishing life, they are not its essence. The core of eudaimonia lies in the virtuous activity of the rational soul. He provides examples of virtuous individuals whose lives, despite potential hardships, are considered good because they lived according to their rational nature.
Critics might question whether humans truly have a singular function or if the concept of telos is too teleological for a modern, scientific worldview. Some argue that life is more a matter of biological and evolutionary processes than of inherent purpose. However, Aristotle's argument is not necessarily about a divinely ordained purpose but about identifying the distinctive capacities that define human nature and how their excellent exercise leads to a fulfilling existence. The function argument, in this sense, is a descriptive and prescriptive account of human flourishing, rooted in the observable capacities of human beings and the pursuit of a life of meaning and excellence. It offers a framework for understanding virtue and happiness not as arbitrary choices but as integral to living a truly human life.