Art should be able to speak for itself, however, art can be imbued with greater meaning with the addition of a title.
For instance, art that is abstract and appears to be representative of no naturally occurring situation is often perceived to have greater depth because of the name that it's artist gives it. Pablo Picasso's "Guernica" is a good example of this.
"Guernica" is considered to be one of the most important art works that capture the horrors of war. The painting itself is a clear testament to chaos and agony. Broken bodies, growling animals, disembodied shocked faces and a severed arm holding a broken sword indicate that this scene shows an attack with many victims.
But looking at the painting does not immediately telegraph to an observer that Picasso's affecting 1937 work is meant to represent the bombing of Guernica during the Spanish Civil War. But because Picasso named his cubist painting after a well known and extremely topical atrocity the piece was looked at with instant revered respect at the time and has grown as an anti war symbol in the ensuing years.
In some cases, art that has observable meaning can be made better with a title that heightens the piece's obvious values. Elizabeth Lowell's novel "Where the Heart Is," illustrates this phenomenon by describing an interaction between one of the book's protagonists and a temptingly touchable work of modern art and its tongue in cheek title.
"The shape of the sculpture was utterly abstract, resembling nothing in the real world. Yet the flowing curves and satin texture somehow cried out to be touched. For several moments Cain did just that, running his fingertips from one fluid curve to the next. After another slow tracing with his hands he looked down and saw the title of the sculpture: I Love You, Too.' He threw back his head and laughed with delight."
Meaningless art can't be given meaning just because it calls itself great art. But tagging it with a title that indicates that the artist knows the viewer is about to dismiss it as pretentious changes what that sculpture, or painting, or large scale multi media instillation; because that previously haphazard artwork can know serve as a topic of conversation which gives it value to the art world. Case in point: Duchamp assured his place in many "What is art?" conversations by taking a urinal away from its usual home and displaying it as art with the name "Fountain."