Let's begin with the Greek philosopher Plato, who said art is the imitation of reality – but it's an imperfect copy.
Aristotle disagreed with Plato, saying that art can express universal truths. It can show us how the world might be – not just mimic everyday reality.
In the Middle Ages, Thomas Aquinas said brightness, completeness and harmonious proportions are the keys to beauty.
Renaissance artists upheld the Greek ideals of art. Their frenemies, the Mannerists, got creative with stylized poses. They didn't get as many likes.
For Immanuel Kant, fine art isn't about getting likes or selling perfume: it is its own goal. Art also meets strict rules while appearing natural. This can't be taught – it requires genius, or a Kardashian.
The Romantics were inspired by heightened emotions like the Sublime – which Kant defined as the experience of the "absolutely great".
While the Realists depicted day-to-day life in a naturalistic way, tagging it #nofilter.
But the Modernists rejected both traditions. Throwing out the certainties of the past, they experimented with bold new ways of seeing.
This reached its height in Dadaism, which challenged attempts to define art and the very idea of aesthetics. Marcel Duchamp famously exhibited ready-made objects as art. Some didn't get it.
Walter Benjamin said that copying technology has destroyed the "aura" of unique works of art, making art less cult-like and more democratic. He also said the aura is being replaced by the cult of celebrity.
Theodor Adorno raged against vapid pop culture that is making us easy to control, saying that capitalism gives us the "freedom to choose what is always the same".
But sociologist Pierre Bourdieu said taste in fine art is just a way for the dominant class to establish their position in the social hierarchy.
And Joseph Beuys said everyone can be an artist. Even the act of putting on lip balm can be a work of art "if it is a conscious act".
Feminist film theorist Laura Mulvey pointed to how women are depicted as objects of the "male gaze".
Writer Susan Sontag said the art of photography stops us from intervening in the world, since we are too busy taking the picture.
Postmodern artists lol’d at the idea of a grand, unifying way of seeing the world. So they mashed up historical styles, turning art into an endless Throwback Thursday.
Other artists explored what philosopher Julia Kristeva calls "the abject" – a radically excluded dimension of human reality – by using gross materials like bodily fluids.
And critic Nicolas Bourriaud coined the term "relational aesthetics" for art that focuses on interactions with real people.
These are some theories of art from the Western canon. But there’s plenty of other aesthetic traditions out there, just like there are lots of Kardashians. What’s your theory of art?
Got a theory you'd like me to oversimplify? Hit me up on Twitter at @chrisrodley.