The philosophy of love
The Wall of Love in Montmartre, Paris, France
'“The parched earth loves the rain
And the high heaven, with moisture laden, loves
Earthwards to fall." - Euripides
According to the ancient Greeks, there are three main types of love: Eros, Philia, and Agape. And each is characterized by love's object, whether love is a means to an end, and whether the love is reciprocated. In my examples, I'll use Romeo as the person who loves, or the subject, and Juliet as the beloved, or the object.
Eros
Eros is an intense desire for an object. It's more of a selfish love because it depends on the value of its object (i.e. the individual's virtues—usually goodness and beauty—and a desire to possess those virtues). It can even arise from the individual identifying some aspects of themselves in the object. Here, the beloved is a means to an end and doesn't have to reciprocate the subject's love.
Some also associate Eros with sexual desire since it can be considered an intense passion and can involve physical attraction, but this isn't a sufficient response for the Eros that Platos and Socrates describe.
Plato's version of Eros is the desire to possess absolute beauty forever. In Plato's Symposium, Socrates gives a speech at a banquet on the nature of love after speaking with the priestess Diotima. He goes through the following line of reasoning:
Eros is a love of something.
Eros must be a love of beauty because it cannot be a love of ugliness.
Love implies a desire for its object, beauty.
You only desire things you don't have.
Because love desires beauty and you desire what you lack, this means that love is not beautiful. But this doesn't mean love is the opposite (ugly), it's just something in between.
Beauty in its absolute form is inseparable from goodness (Socrates says "what is good coincides with what is beautiful"), which also means that love desires and lacks goodness.
The form of love is like that of a spirit, halfway between mortal and immortal, that bridges the gap between the heavens and earth. It functions to interpret and convey messages to and from the gods. Thus, love is a sort of portal to divinity.
According to Diotima, the intense desire of love is expressed as "procreation in what is beautiful," which can be either physical or spiritual and is to "bring forth in beauty." Importantly, Diotima says that "procreation is the nearest thing to perpetuity and immortality that a being can attain." Procreating beauty is what brings humans closer to immortality and divinity.
Thus, love is the desire to possess beauty (and therefore goodness and divinity) forever (by procreating and perpetuating beauty).
Here, Eros transcends physicality and is ultimately a love not for physical beauty but for what beauty in its absolute and purest form represents: goodness and divinity. Physical beauty is just a gateway to realizing this and the beloved is a means to obtaining comprehension and possession of the ultimate form of beauty.
To make this last part more concrete, let's use an example:
Romeo loves Juliet because she's physically beautiful.
Romeo realizes that not just Juliet is beautiful, but many others around him are. Thus, physical beauty isn't specific to Juliet but is a quality that many exhibit and Romeo can appreciate their beauty too.
Then Romeo moves from physical beauty to beauty of the soul (is Juliet kind, virtuous, good, caring, etc.?) and realizes the latter is more valuable and the former fleeting and impermanent.
Now he can move beyond beauty as merely a physical trait and can contemplate and appreciate the true nature of beauty (which lies in the soul) in its intrinsic form.
Beauty in its purest form is united with goodness, divinity, and truth. This is what Romeo is aspiring to attain by being with Juliet.
This isn't a totally convincing definition for the modern sense of love—it's hard to believe that love is independent from and not specific to another person. It doesn't seem accurate that love is using another person to gain insights into truth.
Philia
In his Nicomachean Ethics, Aristotle describes love as an intense and fleeting feeling. And similarly to Eros, love is rooted in beauty: "pleasure in the sight of a person is the germ of love." He goes on to cite the three reasons why we love something: it's useful, it's pleasing, or it's good for us (or at least we think it is). Thus, again, love is motivated by self-interest and seems to be pretty superficial.
Aristotle's notion of Philia is essentially friendship, and he advocates that friendship is more important than love (which is an ephemeral feeling) because it lasts. There are certain conditions that are required for an ideal and lasting friendship, for instance:
Romeo and Juliet wish each other well, and they must do this for the other's sake, not for their own benefit.
To wish each other well without ulterior motives, both Romeo and Juliet must be good people and have good character (e.g. they're trustworthy, level-headed, don't hold grudges, etc.).
Romeo and Juliet have similar values, virtues, or interests, and take pleasure from the same things. Then their friendship will endure as long as these virtues and interests endure.
Philia is a noble, virtuous friendship that involves loyalty and respect, and you have to be a good version of yourself to experience and give this. The value of Philia here is that it promotes self-knowledge, since the beloved/friend acts as a mirror, reflecting your character.
False and fleeting friendships are the opposite of the above:
Romeo wishes Juliet well because it will benefit him.
Similarly, the friendship is motivated by pleasure or profit, and Romeo is friends with Juliet because she does nice things for him (the friendship is a means to an end). Once Romeo gets what he needs from the friendship, it will end.
The friendship is imbalanced—significant inequality is likely rooted in or will lead to the relationship being motivated out of utility where one person wants something from the other.
It seems like the most important quality of friendship to Aristotle is that it lasts. Maybe because if a friendship doesn't last, this means it isn't rooted in intrinsic factors and is therefore superficial. Aristotle values friendship because it can provide goodness, which is an end in itself.
He also devalues love because it's based on physicality and emotion, both of which are impermanent and the former is a means to satisfying pleasure: "the lover delights to look upon his beloved, the beloved likes to have attentions paid him; but when the bloom of youth is gone, the friendship sometimes vanishes also."
Agape
Lastly, we have Agape which is a selfless, unconditional love. It primarily gets its meaning from its use in the Bible—Agape is the Christian notion of God's fatherly love for man and man's love for God.
In the Bible, Agape is used as the word for love (translated from Greek) in John 3:16 when God sent Jesus to redeem mankind of their sins: "For God so loved the world that he gave his only Son, so that everyone who believes in him may not perish but have eternal life." Here, the depth of love is conveyed by the level of sacrifice; God's love for man was so extreme and unselfish that he gave up his only son to redeem them. It's the highest form of love and is derived from ultimate goodness.
Similar to Philia, Agape is love without ulterior motive, but it doesn't require love to be reciprocated and isn't dependent on the value or characteristics of the object, e.g. Romeo loves Juliet and wishes her well but wants nothing in return.
Agape is also used earlier in the Bible in the Sermon on the Mount (a series of teachings Jesus gave to his disciples on a mountainside):
"You have heard that it was said, 'You shall love your neighbor and hate your enemy.' But I say to you, Love your enemies and pray for those who persecute you, so that you may be sons of your Father who is in heaven; for he makes his sun rise on the evil and on the good, and sends rain on the just and on the unjust. For if you love those who love you, what reward have you?" Matthew 5:43-46.
Here, the onus is on the morally superior person to extend love to others. And it's a more difficult love to practice since it requires you to love your enemies. It's easy to love someone who's beautiful or who you're romantically interested in, but it's important to consider what it takes to love your enemies—forgiveness, understanding, empathy, goodness, etc.
While Agape seems to be an end in itself, loving for the sake of it, the lines in Jesus' above sermon conflict with this—loving your enemies “so you may be sons of your Father” and for “reward” imply that men should love not for the sake of it, but to get their place in heaven. It isn't clear to me whether Agape is an end or a means to an end.
Conclusion
With Eros, love is a means to obtaining the virtue of goodness and divinity (which can be realized through contemplating and procreating beauty). For Philia, love is essentially valueless because it doesn't last and instead we should focus on ideal friendships which have their ends in the virtue of goodness. With Agape, love requires sacrifice and is the highest form of selflessness you can exhibit.
These answers still seem insufficient to understand the modern notion of love, otherwise, it seems like there must be more kinds of love out there.
If you liked this post, check out these:
Toltec wisdom on love and the nature of life
Sources:
0328_Bk_SM.pdf (libertyfund.org)