Stand in front of a sunset, a cathedral or a three-minute pop song and you may feel that something matters, though it is hard to say what. Aesthetics is the part of philosophy that tries to say it. Aesthetics is the philosophical study of beauty, art and taste: what we mean when we call something beautiful, what makes an object a work of art, and whether judgments about either can be right or wrong.

Where the word comes from

The questions are ancient, but the name is not. The German philosopher Alexander Baumgarten named the field in the eighteenth century, from a Greek word for perception by the senses. He used it in a 1735 dissertation and then as the title of his unfinished Aesthetica, which began to appear in 1750. Baumgarten thought the senses had their own kind of knowledge, less clear than logic but rich and vivid, and he wanted a science of it. The name stuck, and by the end of the century aesthetics was a recognized part of philosophy.

That origin is worth remembering. Aesthetics is not only about museums. It begins with the ordinary fact that people notice how things look, sound and feel, and care about it. A carefully set table, a well made tool and a friend's handwriting all invite aesthetic attention.

Beauty as order and proportion

For most of Western history, the leading answer to the question "what is beauty?" was mathematical. Followers of Pythagoras noticed that pleasing musical intervals come from simple ratios of string lengths, and many concluded that beauty in general is a matter of proportion. Aristotle wrote in the Metaphysics that the chief forms of beauty are order, symmetry and definiteness. The Roman architect Vitruvius applied the same idea to temples and to the human body. Historians sometimes call this the Great Theory: the Great Theory held that beauty consists in the right proportion and arrangement of parts.

The theory explains a good deal, such as why a lopsided face or a building with one oversized window can look wrong. But the Greek philosopher Plotinus, writing in the third century, pressed a serious objection. Plotinus objected that simple things with no parts, such as gold, lightning or a single color, are beautiful too, so beauty cannot be only a relation among parts. Later critics added that some perfectly regular things, like a grid of identical windows, are simply dull.

Plato: beauty as a ladder

Plato went further. In the Symposium, a wise woman named Diotima describes a ladder of love. A person first loves one beautiful body, then sees that beauty is shared by all bodies, then comes to value beautiful souls, laws and kinds of knowledge, and at last glimpses Beauty itself, eternal and unchanging. For Plato, the beautiful things we see are imperfect copies of a perfect, unchanging Form of Beauty. On this view beauty is fully objective: it is out there, and the soul climbs toward it.

Plato's ladder ties beauty to goodness and truth, an idea that runs through Western thought. John Keats echoed it in 1819 at the close of his "Ode on a Grecian Urn": "Beauty is truth, truth beauty." Critics answer that beautiful things can deceive and that cruel things can be beautifully made, a problem this course returns to when it takes up art and morality.

The turn to the observer

In the eighteenth century, British writers shifted the question from the object to the person who perceives it. Francis Hutcheson argued in 1725 that we have an inner sense of beauty, working much like a sense of sight. Hutcheson said our sense of beauty responds to uniformity amidst variety. A row of identical boxes has uniformity without variety; a junk heap has variety without uniformity; a tree, a fugue or a well planned city has both.

That move, from asking what beauty is to asking how we experience it, sets up the great debate that follows. Objectivists say beauty is a real property of things, while subjectivists say it is a feeling in the observer. Most philosophers since the eighteenth century have looked for a position somewhere in between, one that respects both the object and the person looking at it.

Worked example: the sunset and the parking lot

Imagine two photos from the same evening: a sunset over the sea, and the same orange light falling on an empty parking lot. Most people call the first beautiful at once. Try each theory on it. The Great Theory points to the composition: the clean line of the horizon, the balance of sky and water. Plato would say the scene shares, imperfectly, in Beauty itself. Hutcheson would point to uniformity amidst variety: an even sweep of color broken by waves and clouds. Plotinus would add that even the plain glow of the light, with no parts at all, is part of the pleasure.

Now look harder at the parking lot. The long shadows of the lamp posts fall in a regular pattern, and the low light turns cracked asphalt gold. Many photographers have built careers on scenes like this one. If you begin to find it beautiful, has the lot changed, or have you? That question, whether beauty is discovered in the world or supplied by the viewer, is the thread running through this whole course.