Principles are a critical element of art that are all too frequently abandoned in favor of "expression" in today's namby-pamby art world. Why such venom? Because by moving away from rigid principles, we fail to give students of art tools on which they can build a career.
Let's face it, the vast majority of artists will never make it big as artists. The best that they can hope for is to be an artistic craftsman of sorts. People need images, an artist manufacturers those images. It's not as romantic as dying from liver toxicity only to be hailed as a genius years later, but it pays the bills. And you don't die of liver toxicity.
But if you don't have some divine engine within you producing something that will be hailed as genius, how are you to produce something of worth? Principles, that's how. A framework, instructions, rules to make stuff by. Principles give you the ability to construct something as opposed to simply groping your way toward something that "looks good." With principles, we provide ourselves a framework on which we build.
That said, principles are guides, not shackles.
This is something that is repeated like a mantra by artists the world over before they ever understand why principles are so damned important. They say it because it is an easy dodge from doing the hard work of knowing what you want to say before you speak. But like so many cliches, when spoken by someone who truly understands what is being said, there is great wisdom in this.
As an artist, you need to have those principles before you can reject them. That's why the artists that were at the forefront of the modern and post-modern art movements were truly great artists, and why so many modern artists like Damien Hirst cannot hold a candle to them. I don't mean to specifically disparage Hirst, but I do see him as representative of a terrible disease that has suffused through the world of art: that art is an idea, not an actualization.
This is, of course, complete horse shit. If you cannot execute, you are not an artist. You cannot be a poet without knowing how to write. You cannot be a painter without knowing how to paint. And since art is an expression through a medium, you must understand the limitations of that medium.
The first artists to break free from rigid principles of execution were all classically trained. They knew their medium. Picasso was painting still-lifes long before he painted The Guitar Player. Monet knew how to paint realistically before he painted Sunrise.
There is a danger, though, of using those principles exclusively and not taking risks. not evolving. Once principles are crafted, they can always be updated. I want to be clear, though, in saying that an artistic life of reliance on principles is better than an artistic life of simply throwing things at a canvas. While relying on principles will rarely cause one to break new ground, success is all but guaranteed. The likelihood of any one artist being the "next big thing" is so fleetingly small that he or she may as well start playing the lottery as a a five-year plan.
Art must say something. It is its nature as art. Without a statement, it is nothing more than an image, sound, or pile of material. Art is a language in that the artist is attempting to encode data in some form that is decodable. It drives me up a wall every time I hear an artist say that they have left something "up to interpretation." That means that it's not art. You aren't saying anything. You are using a dodge that you have learned in art school.
So even if what you are saying is simple, it's better that people know that. Once you understand the principles, once you are producing things that people want, bend the rules. Break the rules. Go wild. You will always have that grasp on what you want to say while finding new and exciting ways to say it. Art can be wild and exciting, but to be great, you have to be boring, first.