The stereotypical philosopher spends a lot of time holed up in an ivory tower, pondering questions like: What is a self? What does it mean to know? And why doesn’t anyone want to listen to me talk about philosophy?

Real philosophers also wonder why no one wants to listen to them, but they spend a great deal more time outside of the ivory tower, asking questions about how we ought to engage with others in the world. They ask pressing questions about our personal lives, questions like: Why should I care about other people? What does it mean to be a friend? Various thinkers have presented different answers.

1. Pragmatic friendship: Friendships that are good for you

This is the friend who already took the class you’re struggling in right now and did really well in it, the friend who helps you with your pset over brunch. It’s also the friend who always knows what’s happening on campus, whose room is a social hub for lots of people you think are cool.

These are classic pragmatic friendships: you spend time with each other because you get something useful out of it. Ultimately, you know you’re being nice to this person because the relationship is beneficial to you. Most philosophers agree that this kind of friendship is not true friendship. Because you treat that person as valuable only for your own reasons, the friendship is subject to rapid change along with those reasons. Such friendships involve little trust and little long term stability. Once you’ve taken your last final, there’s no need to keep having brunch with your study buddy.

2. Moral friendship: Friendships where you are both good

This is the friend you stay up late into the night talking to about the meaning of life, the friend who makes you want to be a better person, the friend where you ask how their day was because you actually want to know the answer.

Aristotle argued that this is the best kind of friendship, because the moral development that such friends engage in together is both pleasurable and useful. Being an ethical person is inherently fulfilling and makes your life better, so it’s best to have friends who can be ethical with you. This kind of friendship, though, can only happen between people who are on the same moral page. How are you going to stay up late talking if you don’t have anything in common to talk about? How can someone make you want to be better if they’re too far above you? True friends spend time together doing things they both enjoy, and people who do not share the same values and interests are less likely to fully engage with each other that often.

3. Caring friendship: Friendship as a way of life

This is the friend who’s taking 21 units and just went through a bad breakup, the friend who’s struggling with anxiety and self-esteem, the friend who just needs someone to listen and be there to help.

The previous forms of friendship all notably focus on the self: pragmatic friends are useful for your goals and moral friends aid in your fulfillment of the ethical life. This picture of the self, as autonomous and independent, has been heavily critiqued by a philosophical framework known as ethics of care, which argues that our primary moral good is to care for others.

In ethics of care, the self is interdependent and relational. Being cared for by others is necessary in order to survive childhood, and our deep memory of that prompts the recognition that our best self is a self that cares for others as well. When we care for our friends, we try to imagine what they’re going through and understand what they need, unfiltered by our own ideas or desires. We may want our friend to just get over their ex because it’s irritating to have to hear about it all the time, but if we care — if we focus on their struggles instead of our own — listening and helping will be a joy. And when we are that friend, the one who needs to be cared for, we shouldn’t feel guilty for asking for help. Instead, we can remember that dependence and vulnerability are necessary and beautiful, and we can respond to the care we receive with gratitude and recognition.

4. Aesthetic friendship: Friendship as a work of art

This is the friend who’s fun and interesting, who wants to go on late night adventures and break the rules. You know you’re not necessarily morally good for each other, but the way this relationship is changing you as a person feels good in a different, important way.

Alexander Nehamas of the Princeton philosophy department presents a strikingly different view of friendship, where its value lies outside the moral realm entirely. Nehamas argues that friendships aren’t about ethical self-improvement or moral character — they’re about beauty. Beautiful things stand out. They catch your attention and keep it, because they are different from everything else you’ve seen. It’s that same kind of beauty we see in a friend: someone who is different in curious, exciting ways. Friendship isn’t about moral parity, but about emotional vibrancy. We keep coming back to friends the way we keep coming back to good books, in the belief that there will always be something new for us to find. Friendships end, Nehamas argues, not when they change, but when each person knows that the friendship can no longer change them.

Each of these models of friendship relies on a different vision of the self, of moral value and of our obligations to others. Each requires something different of us: practicality, moral parity, selflessness, good taste. But ultimately, each fundamentally argues that we are not complete without other people and that if we stay in our ivory towers forever, we will miss something essential to what it means to live a good life.

Contact Eliza Wells as eliza22 ‘at’ stanford.edu.