When we ask the question 'what is abstract art?', we open up a number of broader debates as to 'who, how and why?' too.
Since mankind first smudged and scrawled images on a cave wall we have sought to interpret each blotch and scratch; to find meaning beneath the image before us. It has been this quest to seek meaning in all things that has led us to create abstract art. We are compelled to seek meaning. There is a well known test once used in psychiatric circles called the The Rorschach test. This is a psychological test in which subjects' perceptions of inkblots are recorded and then analyzed using psychological interpretation, complex algorithms, or both. The images are accidental ink blots. Not drawings or photographic images. Totally random, no thought in mind when they were created. However, these abstract images are used by psychologists to prompt responses that can vary quite widely depending on the person interpreting what they 'see'.
Much of my own art is totally abstracted. I relinquish all control of the paint and let it 'do its thing'. I have no preconceived image, shape or concept in my mind as I work. So, you can imagine my surprise when I get comments like, "I really love your seascape painting of the dolphins on an orange sea" or "The one with the flock of birds flying over a hillside". Sometimes, different people 'see' totally differing things in the one painting. You see, we all seek to interpret what we see from our own experiences and memories. It's a natural thing and we all do it.
So, when an artist puts paint on a canvas, the challenge is not to convey a thought or scene, but to elicit a response. To engage and intrigue. I believe the best art 'retains its secret'; regardless of whether it is abstract or literal. The best response an artist can get is when the viewer is bewildered as to how the artist achieved the result. This can be a visceral response based upon in emotional or intellectual effect it has or it can be purely based upon a technical appreciation of 'how on earth did the artist paint, draw or sculpt that?'.
The first artist to be regarded as an abstract artist was Russian, Wassily Kandinsky. His works from the late 19th and early 20th century are non-figurative, non-objective and comprise of random marks on the canvas that are there to 'express' thoughts and emotional response rather than things or events.
The word 'expression' is as important as 'abstract' to this form of art. For, whilst it is not designed to illustrate something, it is created to express a feeling or an idea; to appeal to the subconscious over any literal interpretation.
I believe that symbolism or semiotics distinguishes us humans from all other species on our planet. The pursuit of meaning defines us. Abstract art seeks to celebrate that uniquely human quality with colour, form and passion. And by doing so, allows the viewer to be the expert and controller of the experience the art creates.