Ask what it means to be a good person and you quickly hit a fork that Aristotle and Kant mark better than anyone. One answer looks at the whole shape of a life and a character: a good person is someone who has become brave, just, honest, and wise, and who acts well because that is who they are. The other looks at the principle behind each act: a good person is someone who does their duty, following moral laws that reason can justify. Aristotle is the great champion of the first view, Kant of the second.
Aristotle's virtue ethics puts character at the centre. Morality, for him, is not mainly about obeying rules but about becoming the right kind of person — one who possesses the virtues, each understood as a well-judged mean between extremes (courage lies between cowardice and recklessness, generosity between stinginess and waste). We acquire these virtues the way we acquire any skill: by practice and habit, over time, guided by practical wisdom that reads what each particular situation calls for. The goal of it all is eudaimonia — a flourishing, fully realised human life. On this view, a good act is one a person of good character would do, and doing it gladly, from settled disposition, is part of what makes it good.
Kant's duty ethics puts principle at the centre. What matters morally, he argued, is not your character or the results, but whether you act from duty on a rule you could rationally will for everyone — the categorical imperative. Feelings and inclinations are beside the point; in fact, an act has clear moral worth precisely when you do the right thing even against your inclinations, simply because it is right. Morality flows from reason itself, binds all rational beings equally, and issues in universal laws that hold without exception. Where Aristotle asks what a good person would do, Kant asks what duty demands.
Character or principle?Two shapes of a moral life.
Each view captures something the other can strain to hold. Aristotle honours the intuition that morality is about the whole person — that it matters not just what you do but who you are, and that a good life is more than a series of correct decisions. Kant honours the intuition that morality must be principled and impartial — that right and wrong can't simply depend on your cultivated tastes, and that some things are owed to everyone regardless of character or circumstance. Together with utilitarianism, these two form the great trio of ethical theories, and most moral thinking draws on all three.
As you weigh the rows, notice where your instinct settles. When you judge whether an action was good, do you look first at the person's character and whether a wise, virtuous person would have done it — or at the principle they acted on and whether it could be a rule for everyone? Leaning toward character puts you with Aristotle; leaning toward principle puts you with Kant. And if you want to see how the duty side collides with a third rival — consequences — the companion comparison of Kant and Mill picks up exactly there.