Aristotle, Kant, and Levinas
What are the similarities and differences between the ethics of Aristotle, Kant, and Levinas?
The three philosophers you mention lived centuries apart and lived in different parts of the world; as one might expect, there are significant differences in their ethical views and this can, at least in part, be attributed to the vast differences in their surroundings. Aristotle was a Greek philosopher from the 4th century BCE; Kant was a German philosopher from the 18th century; Levinas was a 20th century French philosopher.
Aristotle's ethics are often described as "eudaimonistic;" this refers to the idea that he regards the best possible human life as consisting in eudaimonia ("flourishing" or "fulfillment" or "happiness"). His focus was on the right kind of life, and here, we already have the first difference with respect to Kant.
Kant, as was common among modern philosophers, focused on good acts rather than good lives. He argued that ethical actions require us to act in a dutiful manner in accordance with the moral law. A good human being is one who acts in accordance with the categorical imperative.
These two conflicting approaches are often called agent-centered (Aristotle) and action-centered (Kant) ethics.
Levinas' ethics falls completely outside this dichotomy and, indeed, is not an ethics in any traditional sense. His manner of conducting ethics was to offer a phenomenological account of precognitive interpersonal interaction. His work is almost metaethical in nature, unlike that of Kant or Aristotle.