Michael Craig-Martin: A is for Umbrella, Gagosian Gallery, London

Brit Art guru's radical vision

To walk into Michael Craig-Martin's new exhibition at the Gagosian Gallery is to be reminded of those children's alphabet books full of bright primary colours, where each letter is accompanied by an image. Yet before we even enter the gallery, our expectations are confounded. The show's title, A is for Umbrella, immediately alerts us to Craig-Martin's ongoing concern with language, meaning and reality. For this is no nursery primer.

Against flat backgrounds of vibrant colour, Craig-Martin reproduces the outlines of everyday objects such as a light bulb, a sandal or an umbrella, which function as signs for contemporary life. Over these, he has painted a single letter or combination of letters that spell words such as SEX, ART, GOD or WAR.

As a species, we are driven by a need to establish meaning. Instinctively, we create these through our interpretation of "signs". Signs take the form of words, images, sounds, acts and objects, things that have no intrinsic meaning but become signs when we invest them with meaning. "Nothing is a sign unless it is interpreted as a sign," declared Charles Sanders Peirce, the founder of American pragmatism.

Anything can be a sign, so as long as someone interprets it as "signifying" something and it refers to, or stands for, something other than itself. We interpret things as signs largely unconsciously by relating them to familiar systems. A perfect example is a Coca-Cola bottle that becomes emblematic of the American way of life, or Magritte's Pipe or Jasper John's Flag, which, though primarily common visual objects, have been moved a stage further and divorced from their symbolic connotations and reduced to something "in themselves". It is this use of signs that is at the heart of semiotics, the philosophical system central to the work of Craig-Martin.

His highly stylised images of everyday objects imply the existence of a prototype, the "real thing" once seen and experienced. But in his paintings he dissolves the coherence of these objects so that the lines of one thing flow into those of another, and we are left struggling to make sense of the work before us. Colour is the major key used to delineate forms in these pictogram-like images layered with text. Objects are freed from their representational function and reduced to their formal characteristics so that there are just enough visual clues left for them to be universally read.

The form of one object a drinking glass, say intertwines with another such as a light bulb so that we are hardly able to tell them apart, just as we barely consciously distinguish most of the everyday objects in our lives. Our eye flows between these shapes, only partially making sense of them, a process of association that often occurs with reading and language. For the sort of seeing that occurs in front of these paintings is not seeing as "recognition", but as understanding. Craig-Martin is continually asking us about the nature of perception.

Although born in Dublin, Craig-Martin grew up and was educated in the States, where he studied fine art and architecture. His involvement in the postgraduate course at Goldsmith's College of Art, which produced the Frieze generation, along with his celebrated An Oak Tree (1973), a glass of water presented on a shelf that questioned the nature of reality, have ensured his prominence in the visual arts scene and influenced the way much contemporary art is read.

While there is no doubt that Craig-Martin's work insightfully tracks not so much the movement of the eye but the processes of the alert mind, this is a vision of the world that looks through a rather narrow telescope, for where in this vision is "birth, copulation and death" the only subjects, according to the poet TS Eliot, worthy of art?

Sue Hubbard

To 31 January (020-7841 9960)