Much of philosophy is seen as a tug-of-war between Plato and Aristotle. Looking at their issues in ethics, what are some of the key differences? How do later ideas of ethics relate back to Plato and/or Aristotle? Give a few examples of connections.


The philosophies of Plato and Aristotle with regard to ethical issues differ in many respects.  Although there are many areas where differences arise, the most important difference in the approaches taken by the two philosophers is how they view ergon or human function and the role it plays in ethics. Each philosopher takes a human function to serve different purposes.

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Towards the end of The Republic, Socrates sets out to prove that everything has a specific virtue which is used to relate its performance with function. The examples given are that the virtue of eyes is sight, while the virtue of the pruning knife is the sharpness that brings about efficiency in the pruning process(Gadame, et al. 1988).

In the same vein, Socrates argues that justice and living are the main virtues of the soul. According to Socrates’ extrapolation, a soul that is non-virtuous would perform functions such as ruling, living and deliberating, very poorly. On the other hand, a virtuous soul would bring about an amicable resolution of the problems relating to the ruling, living and deliberating. After referring back to an earlier argument that justice is the soul’s virtue, Socrates is able to arrive at the conclusion that a just man lives a happy life while an unjust man will live a life full of problems.

Plato’s argument contains one fundamental flaw: when he says that justice is the virtue of the soul, it is unclear whether a sound argument was advanced for this conclusion to be arrived at, especially considering that he previously refutes claims by Thrasymachus that injustice is a virtue (Ausland, 1997). Thrasymachus holds the belief that a person who is unjust always chooses injustice over justice, and that injustice results in conditions that make it impossible for people to work together. Socrates applies this conclusion to the human soul and states that injustice is responsible for preventing different parts of the soul from a functioning incoherent manner, preventing them from achieving a common objective

Aristotle, in the introductory chapters of Nicomachean, examines different types of good ends. He comes up with the conclusion that happiness is the ultimate end for all people to pursue. Contrary to Plato’s views on virtues, Aristotle thinks that the good for anything with a function rests squarely on the performance of the function. On the question of whether there is a specific function that is unique to all human beings, Aristotle starts by excluding the nutritional and growth function, since, he says, neither of them is applicable exclusively to human beings.  Secondly, he excluded what according to him is a life of ‘sense-perception’ because this trait is not present solely in human beings. Finally he concludes that the human function serves to utilize that part of the soul which exhibits reason.

Having made this claim, Aristotle sets out to put forth a set of arguments connecting human function to the utilization of reason, and ultimately, the determination of good and bad. According to Aristotle, a man who functions excellently is one who expresses reason in the most excellent manner. The next step in Aristotle’s argument is providing proof that all functions are completed well when done in a manner that displays all the corresponding virtues. Thus, for Aristotle, for any human being to be happy, he must lead a life that successfully expresses reason all the time.

The main differences in the arguments propounded by Aristotle and Plato become clear upon examining the goals that each of the philosophers wanted to achieve. Plato’s arguments put forth two main goals: the first one is to refute the claim that injustice is much better than justice. Secondly, his argument on human function is necessary in the process of setting up the idea of model cities, whereby each and every person has a unique function to play and that the city becomes virtuous when every individual performs his function in the right manner.

Aristotle,on the other hand,sets out to examine happiness, which he considers the ultimate end and for this reason, his main goal is to search for different ways of getting that end. He proves that this good can only be arrived at through an expression of reason. Additionally, he succeeds in prescribing a path that leads to happiness. One only needs to fulfill his function and express reason in an excellent manner in order to attain happiness.

            The arguments propounded by Plato and Aristotle also differ in the way the human function is conceptualized. For Plato, the human function is about deliberation, living, ruling and ensuring that all things are properly taken care of. For Aristotle, human function means performing activities that accurately express reason. These two conceptions of the same idea represent not only subtle differences; they also illustrate the underlying chasm in how each philosopher thinks about human function.

 In conclusion, Plato and Aristotle approach the issue of ethics from different dimensions. However, they both set out to explain the role of human function for a proper understanding of ethics. While Plato thinks of human function in terms of the role that a human being should play in society, Aristotle takes an individualistic viewpoint, whereby the expression of reason has nothing to do with the relationship that one has with his community but rather, only relates to the individual.


Gadame, H. et al. 1988. The idea of the good in Platonic-Aristotelian philosophy, New Haven: Yale University Press.

Ausland, H. 1997. On reading Plato Mimetically, The American Journal of Philology118 (3) p. 371-416.

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