Rose asked:

Compare and contrast the moral philosophy of Aristotle and Kant?

Answer by Tony Fahey


It is in his Nicomachean Ethics that Aristotle sets out his ethical theory: his concept of what it is, for human beings, to live well. For Aristotle, the end or final cause of human existence is eudaimonia. Eudaimonia is most commonly translated as ‘happiness’, but a more accurate translation is ‘flourishing’. Aristotle believed that the desire to live a fulfilled life is part of what it is to be human. A eudaimon life is a life that is successful. It is important to relies that what Aristotle means by happiness/ flourishing has nothing to do with physical pleasure, but is an activity of the mind/ soul in accordance with virtue. (NB for the ancient Greeks, soul was a synonym of mind.)

For Aristotle there are two parts to the mind/ soul: the intellectual and the emotional. Correspondingly, there are two types of virtue: intellectual and moral. Moreover, virtue, whether intellectual or moral, is a disposition (a natural inclination) of the mind/ soul, which finds its expression in voluntary action – that is, it is consciously chosen.

Moral virtue is expressed in the choice of pursuit of a middle course between excessive and deficient emotion, and exaggerated or inadequate action: this is the famous doctrine of the Golden Mean, which holds that each virtue stands somewhere between two opposing vices. Thus, courage or fortitude is a mean between cowardice and rashness; and temperance is the mean between licentiousness or profligacy and insensibility. Justice, or ‘fairness’, the most important virtue of the moral virtues, is also concerned with a mean in the sense that it aims at each person getting neither more nor less than his or her due. However, it is not like other virtues, flanked by opposing vices since any departure from the just mean, on either side, involves simply injustice. Moral virtue prevents disordered emotion from leading to inappropriate action. What decides, in any situation, what is appropriate action and the correct amount of feeling, is the intellectual virtue of prudence or practical wisdom (phronesis): this is the virtue of that part of reason that is concerned with action.

The virtue of the speculative part of the reaction is learning, or philosophic wisdom (Sophia): this virtue finds its most sublime manifestations in more or less solitary contemplation (theoria). Supreme happiness, according to Aristotle, would consist in a life of philosophical contemplation. However, whilst this would be the ultimate in human fulfilment, it is also a life that is beyond the realization of mere mortals. The best we can aspire to is the kind of happiness that can be found in a life of political activity and public magnificence in accordance with moral values.


Central to Kant’s moral philosophy is the view that right actions are those actions that are not instigated by impulses or desires, but by practical reason. Right action is right only if it is undertaken for the sake of fulfilling one’s duty, and fulfilling one’s duty means acting in accordance with certain moral laws or ‘imperatives’. To help us identify those laws which are morally binding Kant has provided us with the ultimate calculus: the ‘categorical imperative’ which states ‘Act only in accordance with the maxim through which you can at the same time will that it become a universal law’. To the categorical imperative, Kant offers a codicil which relates specifically to human will; ‘so act that you use humanity, whether in your own person or in the person of another, always at the same time as an end, never merely as a means’.

Whilst Kant’s moral philosophy can be said to hold considerable merit, in that it advocates that human beings should be treated as ends in themselves rather than means to ends, I would argue that, as an ethical theory, it fails in that it looks on people, not as sentient beings, but as duty automatons. Thus, it seems to me, of the two theories, by virtue of its rejection of closure in relation to what it is that determines right action, and its view that it is one’s natural disposition to seek to lead a life of excellence, Aristotle’s ethical theory is the closest we have come to identifying an ethical theory that requires the least alteration to allow us to lead an ethical life.