Mill, Kant, Plato, and Aristotle



John Stuart Mill


The principle of utility or greatest happiness principle - Actions are right to the extent that they promote  happiness for anyone affected by them, and wrong to the extent that they promote unhappiness. Happiness is pleasure and the absence of pain, and unhappiness is the reverse of this.


The pleasure principle (hedonism) - Pleasure and freedom from pain are the only things desirable as goals. All other desirable things are desirable because they produce pleasure or prevent pain.


Doctrine of the swine objection - By supposing that life has no higher goal than pleasure and lack of pain, the utilitarians represent human nature in a degrading light since human beings have the same goal in life as pigs and other animals.


Mill responds by distinguishing two different types of pleasures: sensual or bodily pleasures (e.g., eating, sex, drunkenness), which both human beings and animals experience, and mental pleasures (e.g., viewing art, reading a good book, moral satisfaction), which only human beings experience. According to Mill, pleasures differ quantitatively according to their intensity, and qualitatively according to whether they are bodily or mental.


Mill contends that human beings are different than animals not only because human beings can experience mental pleasures, but also because human beings prefer the mental pleasures to the bodily pleasures. He argues for this point by claiming that those people who are competently acquainted with both sorts of pleasures (e.g., people who are cultured and well educated) are the only qualified judges, and maintaining that these people prefer the mental pleasures.


Too high for humanity objection - By demanding that people always promote the general interest of society, utilitarianism requires more than human beings are capable of fulfilling. This is because it requires us to shortchange our private interests.


Mill responds, first, by arguing that the consequence of an action can be good even if the motive is bad, as in the case of someone saving a person from drowning with the hope of being rewarded. Accordingly, people who are motivated by self-interest can promote the general interest of society. As this shows, Mill determines the rightness or wrongness of an action according to its consequence – whether pleasure is produced or pain is prevented – and not the motive of the agent.


Mill also responds by maintaining that it is rare that an individual has the opportunity to make a significant contribution to the well-being of society. We should sacrifice our own interest in cases such as this, but in all other cases, our self-interest is weighed more evenly against the interests other people. Consequently, it will not be necessary for us to sacrifice our self-interest as often as the objection suggests.


Lack of time objection - Utilitarianism requires a complicated calculation of the consequences of all possible courses of action. Often, there isn’t enough time to do this before one has to act.


Mill agrees that a utilitarian calculation is complicated, but he responds that these calculations have already been made and are found in common moral rules, such as ‘never lie’. These rules determine the tendency of actions to be beneficial or harmful. Mill compares our use of the ready-made calculations found in moral rules to sailors using the ready-made calculations in astronomy charts to navigate ships rather than doing all of these calculations from scratch. At the same time, Mill thinks that these moral rules can always be refined and further perfected since there are exceptions to these rules (e.g., lying is acceptable when it results in something significantly good, such as saving an innocent person’s life).



Immanuel Kant


According to Kant, the only unqualifiedly good thing is a good will. Other things that we would tend to describe as good, such as intelligence, courage, character, health, and happiness are not always good because they can be used for immoral purposes or be undeserved by the person who possesses them. A good will is the only thing that is always good.


Kant maintains that a good will isn’t good because of its consequences – it is good even if it is useless. He claims that we would call a well-intentioned but clumsy person moral even if they cause more harm than good. What this shows is that for Kant, in contrast to Mill, morality is a matter of the intentions of the agent acting rather than the consequences or effects of the action.


Kant sets out to elucidate the nature of good will through the concept of duty. In order to find a clear example of a good will, according to Kant, we need to identify cases in which a person is motivated by duty. In cases where the commands of duty agree with self-interest, such as the case of the honest shopkeeper example, it is difficult to determine which one is motivating us. Consequently, Kant provides examples in which duty and self-interest conflict, so that it is clear that the agent is motivated solely duty. Two examples of good will that Kant cites are the extremely distraught person who decides not to commit suicide because it is immoral, and the cold-hearted philanthropist, who does not get any pleasure from benefitting others, but does it because he or she believes that it is morally required.


Duty, according to Kant, takes the form of the moral law. The moral law, like public laws, always applies to us, and applies to everyone in the same way. Because of this, Kant describes the moral law as a categorical imperative – an exceptionless command. The moral law is universal, in contrast to inclinations or desires. Inclination is quite different for each person: What pleases you is not the same thing that pleases me. In contrast, moral laws are universal because they apply to every agent in the same way.


Kant gives a number of different formulations of the categorical imperative, which he claims are equivalent to one another in meaning. The most famous is the universal law formulation.


Universal Law formulation - Act only in such a way that the rule you act under (maxim) can become a universal law. In other words, only act in ways that any other agent can act.


For example, Kant argues that it is always immoral to lie. This is because when I lie, whether or not I am aware of it, I expect other people to tell the truth. If everyone lied, we wouldn’t trust one another, and my lie would not be effective. Since the goal of telling a lie is to deceive other people, I expect other people to do something that I myself am not willing to do, i.e., tell the truth. Consequently, we could say that for Kant, the problem with lying is that it sets a double standard: I expect others to tell the truth, but make an exception for myself. Lying cannot be a universal law because it is not an action that everyone can do.





Plato supports his claims about the virtues of wisdom, courage, moderation, and justice by maintaining that the soul is divided into three parts, a rational, spirited (emotional), and appetitive (desiring) part. The virtues are either located in a particular part of the soul or in the relationship of the different parts to one another.


Wisdom - Knowledge about how to govern the soul as a whole. Not knowledge of particular sorts of actions, such as carpentry or driving a car. According to Plato, this knowledge is found in the rational part of the soul, which is the part best suited to govern the soul.


Courage - Holding firm on one’s views of right and wrong in the face of the temptations of pleasure or fear. According to Plato, the virtue of courage is located in the spirited part of the soul.


Moderation - The balance or mastery of our desires. Moderation does not consist in ignoring our desires: They should be satisfied to some extent, but not be allowed to get out of control. Plato describes moderation as harmony or accord in the soul, a harmony that arises out of the agreement of all three parts of the soul that the rational part should govern the other two parts. As a result, emotion and desire are voluntarily restrained.


Justice - Minding one’s own business by fulfilling the function that one is best suited for and not interfering with the tasks of others. Justice leads to an orderly and productive relation between the parts of the soul: The rational part rules since it is the part best suited for this, and the spirited and appetitive parts do not interfere.





According to Aristotle, virtue is a mean between two extremes, i.e., an intermediate state between a vice of excess and a vice of deficiency. He argues that the mean is not necessarily the average or half way point, but rather changes in relation to each individual. For example, an athlete needs to eat more than a regular person, so the mean between too much food and too little food is different for the athlete and non-athlete. According to Aristotle, it is very difficult to discover the mean, to discover the exact point between the two extremes that is best suited for you. As he says, there are many ways to be wrong and only one way to be correct.


Virtues pertain to the proper amount of feelings and actions. For example, in pleasures and pains, the mean is temperance, the excess is intemperance, and the deficiency is insensibility. In giving and taking money, the mean is generosity, the excess is wastefulness, and the deficiency is ungenerosity. In truth-telling, the mean is truthfulness, the excess is boastfulness, and the deficiency is self-deprecation.


We read a more detailed description of the virtue of bravery. According to Aritstotle, bravery is a virtue in relation to feelings of confidence and fear. The deficiency of fear is rashness, when a person does not fear extreme danger, which he or she should. And the excess of fear is cowardice, when a person fears situations that he or she should not, such as a sound in the dark or flying on a plane. For Aristotle, the brave person fears some things, but only the most frightening conditions, such as death, having a bad reputation and lacking friends. Even though the brave person fears these conditions, he or she will stand firm in the face of them in the way prescribed by reason.