As a topic that has been repeatedly and exhaustively debated in recent years there are many theories circulating as to what postmodernism's real definition is. Although still largely undecided it is possible to isolate guidelines as to what cultural forms can be considered postmodern and what effects postmodernism has had on our culture. As knowing subjects we can identify postmodernism's impact on art; possibly a cultural area where its impact has been most profound.In contrast to film, literature and other cultural forms the most famous pieces of art are usually the ones considered to be the most innovative and, therefore, at least in the artistic world, postmodernism has been thrust into the mainstream.

Jean-Francois Lyotard wrote 'The Postmodern Explained to Children: Correspondence 1982-1985' (1992) in which he made considerable attempt to define what postmodernism is and its role in culture and society. In this he stated that 'simplifying to the extreme... I define postmodern as incredulity towards metanarratives'.

In another attempt at a definition Dominic Striniti, cited in McGuigan (1999), identifies five defining characteristics of postmodern culture which include the breakdown of the distinction between culture and society; an emphasis on style at the expense of substance and content; the breakdown of distinction between high culture and popular culture; confusions over space and time and the decline of 'metanarratives'. Such characteristics can be found amongst contemporary art and some certainly seem to support the previous definitions of postmodern.However, the central problem in defining postmodernism is that it is widely considered to be a theory which promotes the replacement of rules with ideas and that no one school of thought should be dominant. Therefore, an attempt to define it or apply its rules to a cultural object is fundamentally contradictory. It is possible to summarize postmodernism, with reference to contemporary art, as a convergence of styles, past and present including the use of nostalgia, the introduction of uncertainty, the presentation of the unpresentable, the provocation of debate and the challenge of the boundaries between piece of art and knowing subject.

Art, like all cultural forms, has been in a constant period of transition since it first appeared on the walls of caves. As techniques developed art became increasingly developed and sophisticated. Lyotard states that 'a work can become modern only if it is first postmodern. Thus understood, postmodern is not modernism at its end, but in a nascent state, and this state is recurrent' (1992). Accordingly, each form of art as it emerged could now be considered once postmodern until it became accepted as the norm by society.An example would be the development of perspective painting and realism.

As artists developed their techniques and were able to present the world in a form not seen before. This then led to realism which, according to Lyotard (1992) orders and stabilises the referent allowing them to decode it easily and become aware of their 'own identities and of the approval they thereby receive from others'. This can now be contrasted with contemporary art. Whereas realism relied on presenting and ordering the presentable from a certain view, art then began to aim to present the unpresentable.Berger cited in McGuigan (1999) sums up the contrast between realism and subsequent forms of art preceding the postmodern.

Stating that renaissance art reflected reality as if with a mirror, cubism replaced this with a 'diagram' - a symbolic representation of invisible processes, forces and structures '[aiming] to arrive at a far more complex image of reality than had ever been attempted in painting before. ' This reflects how art changed over the years to reach its current position. What we may consider postmodern.One of the established definitions of postmodern is the convergence of styles, old and new. Bricolage', defined as 'borrowing, mixture, hybridity, even plagiarism - all "despised" practices in high modernist science and knowledge systems became the bricoleur's trademark and postmodernism's signature line', according to John Hartley (2002).

As this year's Turner Prize has revealed contemporary, socially accepted art appears very much postmodern. The controversial Chapman brothers' work contains many characteristics of postmodernism, most noticeably the use of old, traditional styles mixed with more current, often contentious techniques.Their use of Goya's sketchings is an ideal example of this ('Insult to Injury' 2003). Another would be their use of apparent authentic African carvings in the 'Chapman Family Collection' (2002) which are modernised in both subtle and more obvious ways.

The use of shock and controversy creates uncertainty, another characteristic of postmodernism. It calls into question both society's view of contemporary art and society itself by using unpleasant and violent subject matter. According to Lyotard (1992) this is what postmodern art should be doing.Artists should be returning to the fold and healing the community, something which can be achieved by demonstrating its ills. Furthermore, their lack of acceptance within mainstream society and media can be considered postmodern.

However, this can be easily counter-argued given that their nomination must be evidence of their acceptance and renowned art critics have publicly praised their work. Further evidence of postmodernism can be seen in the work of this year's winner Grayson Perry. With a style that has been described as 'kitsch' there are clear examples in his piece 'Golden Ghosts' (2001).The use of traditional looking vases reflects use of the past and of nostalgia, however, in the figures, patterns and text painted on them Perry uses modern images and scenes depicting the less appealing areas and activities of society. In a fashion similar to that of the Chapman brothers he calls into question the more unpleasant aspects of the world in which we live. There is also evidence of life imitating postmodern art as not only have the boundaries of art forms been blurred but also those of gender given Perry's role as a transvestite.

Therefore, not only have art forms converged with each other, but also with life itself as Perry places himself in his work. Postmodernism has, consequently, caused art to become increasingly reflective of everyday life, calling what we know as knowing subjects into question along with existing rules and possibilities and uniting forms of life and culture, past and present. However, their very nomination, according to some, could negate their categorisation as postmodern.Lyotard (1992) stated that for a cultural form to have purchasing power it must be therefore accepted by society and, therefore, not be postmodern. Unfortunately, this contradictory nature makes it difficult for one to tell for sure what may or may not be postmodern.

Cornelia Parker's work 'Cold Dark Matter: An Exploded View' (1991) embodies another aspect of the postmodern, one which many more pieces of earlier years have attempted to do, which is to present the unpresentable. She attempted to present something which occurs in a moment and then is gone.This particular intention is significantly present in artwork from avant-garde artists such as Picasso, de Chirico and Malevich, all of whom Lyotard references in 'The Postmodern Explained to Children' (1992). Such artists could be considered postmodern for their time as through the use of paint they attempted to present what could not be presented by realism, such as states of mind, emotions and alternatives views of the world. He wrote that 'the postmodern would be that in which the modern invokes the unpresentable in presentation itself, which refuses the consolation of correct forms'.

Such criteria is fulfilled by the by the aforementioned artists and Parker, along with Dan Graham's piece 'Present Continuous Past(s)' (1974) which allowed the viewer to become a participant in the art itself. Such is the convergence between the boundaries of art, culture and life. One of Striniti's five defining characteristics of postmodern culture is the breakdown of high and popular culture (cited in McGuigan 1999). Further evidence that we are living in a postmodern culture can be seen in the convergence of different forms of art and culture.

One particular example would be contemporary music videos. Once just an accompaniment to the song, they have now become an art form in their own right. Becoming increasingly artistic in their content, for example, Massive Attack's 'Tear Drop' (dir. Walter Stern 1998) video featured a singing foetus.

Nowadays, musicians become artists, for example Lou Reed has recently released a book of his own artistic photographs; Damien Hirst has directed a music video for the pop band Blur.Culture itself appears to be converging which may continue until there is no longer high and popular culture and today's existing categories and genres may no longer exist. To answer the question what does postmodernism do to art would and has resulted in numerous contradictions as the theory itself is made up of them. However, conclusively, I believe that postmodernism has caused art to not only look to the past and use of nostalgia to create new and provocative ideas and questions but has resulted in the convergence of types and definitions of art itself so that we are no longer certain what is art or what it's role in society is.

No longer is it to decorate our walls as a status symbol. Contemporary art is often inappropriate for display in anywhere but a gallery due to its size and nature. Culture itself is constantly in transition and postmodernism is merely its current state; it could even be argued that we have moved past postmodernism altogether. Rather it is term used to describe the current cultural mood and tone and what it represents.