In the field of aesthetics or philosophy of art, the matter of defining what art is have been debated over for a long period of time. Despite the fact that a conclusive agreement on the matter has never been reached since the ancient era until today, a considerable number of attempts to come up with a proper definition of art has been made through theories of art. Recently, however, Dominic McIver Lopes had presented another theoretical perspective on the definitions of art. According to Lopes, what we need in order to explain the nature of art is an informative theory that can describe antiaesthetic( or hard) cases including avant-garde, which is original and innovative but radical and puzzling at the same time. However, this article aims to demonstrate that his argument is flawed in terms of explaining the nature of art. To this end, I will begin by introducing the philosophical approach to the definition of concept. I will then explore various theories of art that were presented in response to the vexing question: what art is. Thereafter, I will introduce Lopes suggestion on what art is. Finally, I will critically examine his argument regarding the theory of art and show that it is an incomplete one when it comes to defining art.